Thanks for the great video! I have a question about tuning the 175 CD. I have only one in my 1979 MGB. There are two screws that are accessible when the carb is assembled which I believe are the throttle-stop screw and the fast idle stop screw. How do I adjust those to make the engine run smoothly? I've been having an issue where the car runs well until about 2000 rpm but anything higher and the idle rpm drops lower and lower until the engine cuts out. Thank you!
Later CD carbs had 3 visible screws, which (at least in the US) were (usually, but not always) an idle trim screw, the fast idle screw, and the idle speed screw. The idle speed determined where the throttle plate rested, the fast idle screw hits the cam on the choke (if you have one), and the idle trim screw you basically shouldn't mess with since you're not going to notice the difference anyway--you need a gas analyzer for that one. You need a special tool to adjust the mixture of your carb, which I show in a few of my carb videos. Hope that helps!
Depends on the carb you have. One is on the throttle to set the idle speed, another will set the fast idle speed when the choke is on, and the third is an idle trim screw. That one adjusts the mixture, but only very slightly. Not every carb will have it, and you'd need a gas analyzer to use it.
Hey Beautiful piece on how to put your baby to sleep I couldn’t comment on there for some reason but . Beautiful perfect I think it was Somewhere Over The Rain Bow HAPPY FATHERS DAY
13:18 I really work on Edelbrock four barrel carbs but I''m helping someone who has a Triumph Stage fitted with these carbs, one thing we learnt is that if you screw the adjuster fully clockwise it will lift the needle and be fully rich, from that point you ONLY have 3 turns anti-clockwise (counter clockwise) to lean the mixture off, if you go more than 3 (maybe 3.5 turns MAX) then the adjuster will become uncoupled from the needle, then no matter how many clockwise turns you go it will not lift the needle! If you are careful you can gently push on the brass housing that the needle sits in to re-couple the adjuster. Also the way that the adjuster works appears to be backwards for a normal thread, i.e. when turning the adjuster clockwise you would think that the needle is lowered into the needle jet, it is not, it's lifted out of the needle jet, if you take the needle and its brass holder out of a piston you can work out how the adjuster works, its quite clever!
While it's technically possible, the needle really shouldn't become uncoupled. There's a grub screw in the side of the air piston that holds the needle and keeps it from dropping out, so make sure that's in place and properly tightened. At the top end, there's supposed to be a retaining clip that keeps the adjuster from moving up. If you wrench down on it, it'll still move, but you should be able to feel it and know you're turning the tool well past where it should be. Check both those things, since without them it'll be difficult to get the mixture to change accurately.
@@midwestmotoring Yep the grub screw on both pistons was in place, it does stop the needle from turning so that will go up and down on the adjuster thread and like you said it stops the needle from totally falling out of the piston but on the carbs that I worked on it did still allow the needles to fall away from the adjuster. If you think about it, if the grub screw did not allow the needles to disconnect from the adjuster then when the needle bottomed out on the grub screw the adjuster thread (or needle thread) would be damaged if you continued to turn the adjuster in order to lean the mixture. The needle would not be able to move any lower so something would have to 'give'. Anyway if you have a spare piston with a needle fitted I guess you could test this, you could turn the adjuster counter clockwise 10 times, then turn it clockwise in order to see if it lifts the needle. One the carbs that I worked on it wouldn't lift the needles!
This is great I'm working on my e type 4.2 and I would imagine the basics are very similar,, If there is anything I should know before I start,,, can you drop a hint ,thanks Chris
Hi Chris! The main differences will be in the needles used (no procedural change, just a different part number) and potentially how the floats are set. Yours may be at a different height than a TR6 or an MGB. Other than that, most of these carburetors are substantially similar. Some of the attached emissions components also varied between companies. I'd suggest checking in your shop manual to verify the settings, but other than that I can't think of anything off hand.
Poor filming; the exact use of the adjustment tool on the Zenith carb is outside the picture although it seems that, although he says that the carb "is running a bit rich", he turns it to the right - thus making it even richer!
I'll admit after re-watching the video it certainly does look that way. Some of the talking was a voiceover that was recorded later--it's very possible that I made an error and if so I apologize! Hopefully that clears things up, but the procedure really is the same. Thanks for the comment!
working on my neighbours 1950 rillie rms ? changed to electronic ignition and now to adjust the SU carbs after I repair the exhaust leak and water leak thanks for the insite. also there is no oil in the dash pots or a dip stick only brass caps ?
Question - ZS 175CD single carb on MGB. Adjusting the mixture following the same process you show for the dual carbs. Question... doesn't the mix get significantly thrown off when the air filter/air box is installed. Specifically, in my case I felt like I had the carb very well tuned. I installed the factory airbox and restarted the engine. The engine ran very poorly. How could I have compensated for this while doing the adjustments?
@@midwestmotoring Thank you for the reply. That is certainly what I thought believing the airbox/filter is designed for minimum restriction. However, not what I experienced in installing the factory airbox with a brand new filter. I had a person with experience on these suggest tuning the carb with about 1/2 the throat taped off to replicate filter on conditions.
I can promise there's a difference, but not that much. I can see them run more lean or rich, but only with an exhaust gas analyzer plugged in since the difference is very minor. I wonder if there's a restriction in your new air filter, or if there's a hole somewhere that's plugged but shouldn't be. Anyway, if it runs better it runs better... but consider changing to a different style filter if it turns out it's that bad.
I hv benz stomberg carburator it runs rich and plugs get black very quickly , If iam to lean the carburator do I hv to turn the nut below carburator to clockwise or anticlockwise ?
You want the jet to go lower--so you will want to turn it anticlockwise. Check that the choke is not stuck on. If you cannot lower the jet enough, you may need to disassemble the carburetor to set the float height.
So the bypass valve is literally what it sounds like--it bypasses the throttle with enough vacuum and lets in fuel/air mixture. It's controlled by a spring pressing against a plate that seals off the flow. When the vacuum goes high enough to compress the spring, it opens the plate and lets fuel/air flow into the engine. You can adjust the tension on that spring by turning the adjustment screw (if there is one--if there's not, it requires disassembly). The procedure I use is to: 1. disconnect the vacuum retard (if you have it), which should bring the RPM to about 1300 or so. 2. Start with the adjusting screw(s) turned counterclockwise (you'll know it's far enough since the RPM will be able to drop to 1300 instead of staying over 2000--which indicates the valves are "floating"). Turn the bypass valve clockwise until the engine speed jumps up abruptly (you're making it float on purpose). 3. Turn the valve counterclockwise until the RPMs drop back down to the 1300 where it was at. 4. Blip the throttle and watch the engine speed drop back down to 1300. If it stays high, the valves are still floating and you need to adjust it out another half turn until you can rev the engine and it returns to normal. 5. Back it out one more half turn to seat the valve, reconnect everything, and balance the carbs or adjust the slow idle speed on the carb(s) if necessary.
Ah, you mean the thick brass screw on the side with the tapered end. You can think of the floats as being the course mixture adjustment, the needle/jet as the fine adjustment, and the idle trim screw as the very fine adjustment. For most owners it's best to just leave this closed. I believe it's necessary to use a gas analyzer to tell the difference when making this adjustment. Someone else might have more information than I do, but the short version is that it's not necessary to adjust.
New to old British cars, I'm getting ready to restore a TR4. I was just going through the carbs last night. I've been building motorcycles for years, and am used to vacuum syncing. Is there a reason why an air flow meter should be more accurate in setting up a set of 175cd carbs? I noticed vacuum lines on both carbs I was thinking that was for this reason lol.
The vacuum lines on the carbs are not for syncing them. They drive the distributor advance/retard depending on the throttle position and load. An air flow meter is definitely more accurate, but you can do it with a bit of hose and just listen to the sound.
@@midwestmotoring I understand what they are for, but don't quite understand why they wouldn't be able to be used to balance the carbs. For motorcycles you adjust the butterflies so that the vacuum is even, but here your adjusting the butterflies to even inlet air velocity. I just am curious if this is more accurate or if it's doing something I don't understand or am overlooking.
You probably could use them... but I believe only one carb has a vacuum port. You'd need a set with vacuum ports both on the top or both on the bottom (one top, one bottom will not have the same signal).
A timing light pointed at the crankshaft pulley timing marks is the most accurate way to time the engine with any ignition. If you're asking about static timing, my understanding is that Pertonix ignition systems can be static timed in the same manner as points ignition. Set the timing mark on the crankshaft pulley to the desired static timing position. Connect a test light to the switched wire running from the coil to the distributor (the one that is not the power wire) and ground the test light, then turn the ignition on and twist the distributor body counter clockwise until the light is out. Then turn it clockwise slowly until the light comes on. Lock the distributor down and check with a timing light for further tuning.
Hola ! I really learn and enjoy your videos. Your technical expertise and well versed tutorials make the difference. I have a question for you, if you’re so kind. I overhauled a set of strombergs for a friend this week. Step by step as you describe in your video. After installing them and doing the adjustments, etc the car revs up and stays in 1200 to 1400 rpms. I’ve checked for vaccum leaks, none, sticking linkages, good, and everything else that I can think of. The car in question is a 1970 Jaguar e- type. Any suggestions? Again, thanks for all the videos . Felix Diaz Puerto Rico
Sounds like the bypass valves aren't adjusted correctly. They are probably set with not enough pressure on the spring, so they're allowing fuel to bypass at too low an engine vacuum.
Thank you for your videos I have watched them many times and was able to get a 71 TR6 running again after it had been sitting for a few years. I started by changing the fuel pump, then when one of the carbs was leaking I rebuilt them. Later i noticed the vacum retard was leak and replaced that as well. I have the petronics ignition and have the appropriate coil. Question now, is that in low RPM between 1500 and 2000 - when the car is on the road, I am getting back fire. Seems to be fire=ing into the carbs, because the pistons are blackened. I think I have looked at everything multiple time, but can't get the backfire to stop. Do you have any suggestions where to focus? Thanks in advance for your reply
I suspect timing. Sounds like points out of adjustment, but you say you have a pertronix. My next guess would be with the distributor. It's pretty common that these don't advance/retard as they should. Check with a timing light and make sure you're getting full advance AND that it's retarding all the way back at low RPM. Your distributor may need a rebuild. If it does, let me know and I can help.
Yes very, very good info. That said when you are producing a teaching video consider borrowing a muffled Triumph even if your straight pipe baby needs a tune up. I've got a TR6 myself but i didn't make it thru the video because of the joyful noise.
Actually I did put on a new exhaust, which is a stock one. I think I did that before this video, but I'll make sure the sound level is better going forward. Thanks for the feedback!
I know this is a pretty old video but I have a question about where to start when reviving the old carbs on my barn find GT6. They had some issues when the car was still running about 15 years ago but since I've never really worked on carburetors before I'm pretty stumped on what to do.
You're in luck! The GT6 uses CD150 carburetors, which are very similar to the CD175s used on a TR6. This video should help: studio.ruclips.net/user/videowQaRvarG5oY/edit. If you've got a very early GT6, there might be some differences, such as adjusting from the bottom or some differences in how the choke works. By and large, though, it should be nearly the same.
The diapragm cover on the front carb is not fitted correctly. You have it 180' out. The alignment mark on the casting is is not aligned with the one on the carb body. The rear carb has the marks aligned correctly.
Wow, I'm not sure how I've missed that. Good catch! It's actually only 90 degrees out, rotated counter clockwise. Still... too much focus on the camera and not on what I'm doing. I'll head out to the garage now to fix it. Much appreciated.
MUCHAS GRACIAS POR EL VIDEO, ME SERA DE GRAN UTILIDAD,PUES EN ARGENTINA NO SON MUY VISTOS LOS STROMBERG,SE LOS ACABO DE INSTALAR EN UN MOTOR DE 8 CILINDROS L, en una bateria de 4 unidades,la llave para regular las agujas me la fabrique,lo que no tengo es el medidor de flujo,como lo puedo reemplazar,desde ya muchas gracias.
I'm a 78 TR7 with dual Strombergs. Do you have one, or is it pretty much the same as your TR6. I rebuilt the carbs now they seem out of tune and idle too high for one....thank you! PS Tequila for me in gluten free California, though it's not a single carb 1975
They are pretty much the same. 1, make sure you loosen the throttle linkage when setting the idle so the carbs can be set independently. Also push the throttles closed to ensure nothing is sticking. 2, if you can't get the idle down no matter what you do, it's probably one of the bypass valves set too loose. I should like tequila as I'm half Mexican, but it's whiskey for me. ;)
,@@midwestmotoring Just like my cousin.Your better half is disguised, I'm an 1/8th N.A., BTW. I want to know about the two screws on the side of the carb.Is that mixture or the bypass valve? Is this something that is like an art form or can a rookie like me hack it. Maybe there is a good book on it. I'm getting the tools for the job, but getting it to pass smog....well maybe the shop with a gassalizer machine is what is best.Any recommendation and thanks for the reply. Brian
Anyone can work on these. It takes time and a few tools. If I know which screws you're referring to, one is in the bypass valve and the other just above the temp compensator. The one on the bypass valve controls how much vacuum is needed before the valve opens. It should only open at very high vacuum, so if your car is idling fine then don't touch it. If you can't get it to idle below 2500 or so no matter what you do... then suspect that screw. The other is an idle trim screw. As the engine wears in, it's slowly closed off. It's a very fine adjustment and normally you'll need a gas analyzer to even tell the difference. Just screw it in all the way and out maybe half a turn and it's good enough.
Very helpful, I had a MGB before with twin SUs, it was good fun. Now I have a Triumph Vitesse 1967 2 liters inline 6 cyc. with twin Zenith Strongberg Carbs which are running good. What is the tool you use to adjust the fuel richness?
That would be this guy: mossmotors.com/triumph-tr6-250/car-care-garage-tools/tools/tool-carb-adjusting. There are other vendors that sell the same thing, and they all vary slightly but do the same job. It's worth noting that only later Stromberg carburetors use this tool. The early ones adjust by a hex nut on the bottom of the carburetor, and for a year or so in the middle you may even find carburetors that are not adjustable--you have to disassemble them and physically move the needle.
Great video. Question I drove my 75 TR6 at a higher elevation (2400 ft) and stopped to enjoy the view. After about 10 minutes the car was hard to start and I had to use the choke to get going. Once I got back down to sea level it ran fine. Are the TR6 carburetors that sensitive? Thanks
Short answer, yes... though I'd expect a much larger altitude change than 2400 ft. Easy to fix though. If you know you're going high up and have any trouble, just keep an adjustment tool in your car. Wind the needles down a quarter to a half turn and keep on driving, then replace later when you're lower again. Technically though, it should run rich at higher altitude... not lean, so if the choke is what worked, you may have had a different issue such as flooding. Pulling the choke does add even more fuel, but also opens up the throttles too.
Good morning! I have a 1971 Triumph TR6. It has Zenith-Stromberg 175 CD carburetors installed. I have only owned this car for about two months. I noticed on my carbs the fuel inlet that is located on the upper left of the carb is left open(no fuel or even a fuel line). The fuel enters the carb on the lower right fuel inlet on both carbs only. I noticed in this video that you have fuel going to both sides of the carburetors. Should I have the left side receiving fuel as well? The car runs great without any issues although it does idle at about 1500 RPMs. What are your thoughts? Thanks, Randy Gibson, Atlanta, GA
Hi Randy, good question. That's not a fuel inlet, it's a vent. It should be connected to the charcoal canister. On some cars, this has been removed (for no good reason, really). In those cases, if it can't be easily reconnected, you should leave it to vent to the atmosphere as it is or it will leak. Good luck with the TR!
Oh, and the idle can be lowered by undoing the throttle stop screws a little at a time. I think I've got a video on tuning the carbs that might show that a little better. Hope that helps!
@@midwestmotoring Thank you for the quick reply. Like I said I have not had the car for long. It does not have a charcoal canister. The carburetor vents are just left open. I bought a cap for them. I think I will remove the cap and let them vent. As I finish the restoration I will probably add the canister back to make it more like the original 1971. I really appreciate your channel. I’ve learned a lot from you expertise. Thanks again. Randy
Hola Midwest. Felicitaciones por el video, es de gran utilidad. Estuve viendo el Link de Moss y venden una aguja 45 M que aclara que de gran altitud. La pregunta que te hago es ¿Que se considera gran altitud? ¿cuantos metros del nivel del mar?. Gracias.
Hola, y gracias para la pregunta. Lo siento--mi Espanol es terrible! No se si necesitas una aguja especial. Cuando estuve en Colorado con el Spitfire, solamente necesito poner mas rico--no necitaba partes especial. Ahora en ingles: Hi and thanks for the question. I'm sorry--my Spanish is terrible! I don't know if you need a special needle. When I was in Colorado in the Spitfire, I only needed to make it more rich--I didn't need special parts. I hope that helps! Thank you for watching!
Good question! Technically you're referring to what is (on most carbs) the idle trim screw. With Z-S carbs, the trim screw is the finest adjustment with the least amount of range. It will be difficult to find the proper setting without a gas analyzer, so you should just get as close as possible with the needle. The needle, then, is a slightly less fine adjustment. It's what you'll want to give a half a turn or so to when you go into the mountains, or what you should use when tuning the car after doing work. Finally, the course adjustment is the fuel floats. If you haven't got enough range in the needle travel, the float height (and remember there are 2 sides to the float!) may be off. The short answer is that I usually just screw in the idle trim screw all the way and ignore it.
Just put up another video talking about CD carbs. SUs and Strombergs are basically the same apart from some add ons that the strombergs have. I actually like them better in some ways.
Just in general, I don't like the shape of the manifold. You're taking a side draft setup and putting a downdraft carburetor on it--but without much room, so it makes for some inefficient angles. As for the carburetors themselves, there's nothing wrong with them--but the Strombergs on a TR6 are definitely not the limiting factor when it comes to making power. Side draft Webers such as DCOEs are a different story. They have individual openings for each cylinder, and especially in a full-throttle situation can flow more. However, the engine in stock form simply can't pull that much air--so it's a waste without considerable upgrades such as raising compression, changing the cam, modifying the exhaust, and so forth.
Fabulous series on the Stromberg carburetors. Great to have gone to school class. Really appreciate that you simplify with a clear delivery and you’re not afraid to share the odd faux-pas. Combined with your ignition system videos I’ve got my 72 GT6 Mk3 running like it never had since i got it. Did our own schooling on the Lumenition electronic ignition which had a blown IC, replaced for 50p :) One thing i got confused about in my car was i found it had a 12volt coil labelled for a ballasted system. I’d thought it was one or other. 12v non-ballasted or 6V ballasted. At moment I’ve replaced the coil with a 12v with primary resistance of 3.5ohm which matches the spec in the Haynes manual. But would be great to know how to double check if there is or is not a ballast resistor in situ. Any tips for that? Cheers Jim (Glasgow Uk)
Hmmm... So technically, in a points system with a ballasted ignition and the points closed, you have a complete circuit and can see a lower voltage than battery voltage. You'll get something like 8V instead of 12V. If you have a non-ballasted system then you'd see the full battery voltage rather than a reduced amount. This ONLY works with the points closed, since without the complete circuit you'll get battery voltage either way. You may be able to mimic closed points with an electronic ignition. For example, the new XR700 system I believe has an LED light that may indicate when the points would be open/closed (even though there are no points). Alternatively (and this is a question for en electrical engineer or some other qualified person), I believe most voltmeters show the AVERAGE voltage. So if the points are opening and closing (or if your electronic ignition is triggering the coil), you might see the average of 6-8V and whatever battery voltage is. If that's true, then pretty much any number a bit lower than battery voltage would indicate you have a ballasted system requiring a 1.5 ohm coil.
Thank you again. Sorry for tardy reply. Checked that out and I'm getting constant battery voltage levels and think can safely conclude that is an inflated system, the previous coil was incorrect. Think that's the ignition system all in good shape now and the repaired chip in the electronic ignition seems to be holding up well. Getting a little backfiring under deceleration but the car hasnt run for quite some time so plan is to get a few hundred miles and a few trips under the belt and revisit the timing and carb tuning. Thanks again for your videos.
@@jimdarroch2136 I'm happy to help. The backfiring, by the way, can be down to a couple reasons. First off, if you have bypass valves on Zenith Stromberg carburetors, they might be closed off to make them non-functional. A lot of owners have done this, but it makes the car prone to backfiring when letting off the throttle. You might also find that the timing is changing under deceleration. Maybe a weight is sticking inside the distributor or a vacuum capsule isn't working properly? I'd suspect the weights first since the vacuum only moves the timing a few degrees.
Midwest Motoring cheers. I'll monitor it for a bit and check the bypass valve in case prior owners did this. I'll be ready to strip the distributor. Saw a helpful video of that somewhere 😊. I have added oil already. 👍
@@GregSchnittger just generally you don't want to let the engine sit idling for too long while tuning it. You'll get false readings. Best to hit the throttles and then let the RPMs settle just before you raise the piston to check the mixture.
Was the car running fine before? In other words, the car had no issues, you pulled the plugs and put them back, and suddenly the car didn't run right? If so, it could be a coincidence but suggests the plugs are at fault. Did you use the correct type? What's the gap set at?
@@midwestmotoring Hi there is one thing, at some stage could you do a video on crankshaft end play, how to measure it and how to fix the problem with the motor in the car (TR6) Many thanks
@@darrenfechner5613 there is a video on crank end play. I think it's part 1 of getting the TR6 back on the road. I didn't need to show the repair but I've got the Spitfire engine out and will show the process there as well.
I"ll have to get a timing light and a dwell meter! Do you have any plans on doing a video on a coolant flush and refresh for the TR6/GT6 ? I think i read there's something in the head you need to clean out with a wire?
That I'm not sure about. I'm guessing the wire may help to loosen silt in the cylinder head, but that may be necessary mainly when new (to clear out casting bits) and when the maintenance hasn't been done (i.e. the coolant and oil haven't been changed and have left solid gunk inside). I'd recommend having a machinist do that, as you should no doubt have the surface machined if you're going that far. Good question! Thank you!
Excellent video !! I’ll surely watch it again when I’ll be adjusting my carbs on my Triumph GT6 ! You talked about early and late Stromberg carbs concerning the adjustment; do you consider CD150 Stromberg (as fitted on MK2 GT6) to be early or late ?
Good question. It could be either since I'm not sure when they made the change and you may or may not have the original carbs on your car. If there is a hex nut on the bottom, then that will be the adjustment point. Later carbs have a simple brass plug or a slotted screw-in plug on the bottom. There will not be a hex nut. A quick peak at your carburetors should tell you which you have.
I came across your channel by accident and am very happy I did. You do a great job showing and explaining, thank you!
Thanks very much for the feedback. I'm happy to be able to help! Keep that car on the road!
Thanks for the great video! I have a question about tuning the 175 CD. I have only one in my 1979 MGB. There are two screws that are accessible when the carb is assembled which I believe are the throttle-stop screw and the fast idle stop screw. How do I adjust those to make the engine run smoothly? I've been having an issue where the car runs well until about 2000 rpm but anything higher and the idle rpm drops lower and lower until the engine cuts out. Thank you!
Later CD carbs had 3 visible screws, which (at least in the US) were (usually, but not always) an idle trim screw, the fast idle screw, and the idle speed screw. The idle speed determined where the throttle plate rested, the fast idle screw hits the cam on the choke (if you have one), and the idle trim screw you basically shouldn't mess with since you're not going to notice the difference anyway--you need a gas analyzer for that one. You need a special tool to adjust the mixture of your carb, which I show in a few of my carb videos. Hope that helps!
@@midwestmotoring Thanks for this but I can’t, for the life of me, find the third screw. Do you mean the ‘screw’ to adjust the jet within the carb?
Depends on the carb you have. One is on the throttle to set the idle speed, another will set the fast idle speed when the choke is on, and the third is an idle trim screw. That one adjusts the mixture, but only very slightly. Not every carb will have it, and you'd need a gas analyzer to use it.
Hey
Beautiful piece on how to put your baby to sleep I couldn’t comment on there for some reason but . Beautiful perfect I think it was Somewhere Over The Rain Bow HAPPY FATHERS DAY
Thanks so much--yes it was Over the Rainbow! Make sure you watch to the end if you didn't. The out take is worth it.
13:18 I really work on Edelbrock four barrel carbs but I''m helping someone who has a Triumph Stage fitted with these carbs, one thing we learnt is that if you screw the adjuster fully clockwise it will lift the needle and be fully rich, from that point you ONLY have 3 turns anti-clockwise (counter clockwise) to lean the mixture off, if you go more than 3 (maybe 3.5 turns MAX) then the adjuster will become uncoupled from the needle, then no matter how many clockwise turns you go it will not lift the needle! If you are careful you can gently push on the brass housing that the needle sits in to re-couple the adjuster. Also the way that the adjuster works appears to be backwards for a normal thread, i.e. when turning the adjuster clockwise you would think that the needle is lowered into the needle jet, it is not, it's lifted out of the needle jet, if you take the needle and its brass holder out of a piston you can work out how the adjuster works, its quite clever!
While it's technically possible, the needle really shouldn't become uncoupled. There's a grub screw in the side of the air piston that holds the needle and keeps it from dropping out, so make sure that's in place and properly tightened. At the top end, there's supposed to be a retaining clip that keeps the adjuster from moving up. If you wrench down on it, it'll still move, but you should be able to feel it and know you're turning the tool well past where it should be. Check both those things, since without them it'll be difficult to get the mixture to change accurately.
@@midwestmotoring Yep the grub screw on both pistons was in place, it does stop the needle from turning so that will go up and down on the adjuster thread and like you said it stops the needle from totally falling out of the piston but on the carbs that I worked on it did still allow the needles to fall away from the adjuster. If you think about it, if the grub screw did not allow the needles to disconnect from the adjuster then when the needle bottomed out on the grub screw the adjuster thread (or needle thread) would be damaged if you continued to turn the adjuster in order to lean the mixture. The needle would not be able to move any lower so something would have to 'give'. Anyway if you have a spare piston with a needle fitted I guess you could test this, you could turn the adjuster counter clockwise 10 times, then turn it clockwise in order to see if it lifts the needle. One the carbs that I worked on it wouldn't lift the needles!
This is great I'm working on my e type 4.2 and I would imagine the basics are very similar,, If there is anything I should know before I start,,, can you drop a hint ,thanks Chris
Hi Chris! The main differences will be in the needles used (no procedural change, just a different part number) and potentially how the floats are set. Yours may be at a different height than a TR6 or an MGB. Other than that, most of these carburetors are substantially similar. Some of the attached emissions components also varied between companies. I'd suggest checking in your shop manual to verify the settings, but other than that I can't think of anything off hand.
Poor filming; the exact use of the adjustment tool on the Zenith carb is outside the picture although it seems that, although he says that the carb "is running a bit rich", he turns it to the right - thus making it even richer!
I'll admit after re-watching the video it certainly does look that way. Some of the talking was a voiceover that was recorded later--it's very possible that I made an error and if so I apologize! Hopefully that clears things up, but the procedure really is the same. Thanks for the comment!
working on my neighbours 1950 rillie rms ? changed to electronic ignition and now to adjust the SU carbs after I repair the exhaust leak and water leak thanks for the insite. also there is no oil in the dash pots or a dip stick only brass caps ?
The brass caps should unscrew, and there would be oil underneath.
Poor placement of the camera - much details are obscured by his hands or are even outside the picture.....
Sorry for that. This is one of the older videos, so hopefully the camera work has improved for everyone!
Another good practice is to blip each of the 2 throttles after making any idle or mixture adjustment just to settle each carb down.
Definitely!
Awesome. If he's this professional and knowledgeable with his hobby, imagine how high his level is with his profession!
Well if that's not a glowing review, I don't know what is! I'll just leave this here... www.krajniakgroup.com :-D
Question - ZS 175CD single carb on MGB. Adjusting the mixture following the same process you show for the dual carbs. Question... doesn't the mix get significantly thrown off when the air filter/air box is installed. Specifically, in my case I felt like I had the carb very well tuned. I installed the factory airbox and restarted the engine. The engine ran very poorly. How could I have compensated for this while doing the adjustments?
It might make a difference, but not a significant one. If installing the airbox makes things worse, you have a restriction that shouldn't be there.
@@midwestmotoring Thank you for the reply. That is certainly what I thought believing the airbox/filter is designed for minimum restriction. However, not what I experienced in installing the factory airbox with a brand new filter. I had a person with experience on these suggest tuning the carb with about 1/2 the throat taped off to replicate filter on conditions.
I can promise there's a difference, but not that much. I can see them run more lean or rich, but only with an exhaust gas analyzer plugged in since the difference is very minor. I wonder if there's a restriction in your new air filter, or if there's a hole somewhere that's plugged but shouldn't be. Anyway, if it runs better it runs better... but consider changing to a different style filter if it turns out it's that bad.
I hv benz stomberg carburator it runs rich and plugs get black very quickly ,
If iam to lean the carburator do I hv to turn the nut below carburator to clockwise or anticlockwise ?
You want the jet to go lower--so you will want to turn it anticlockwise. Check that the choke is not stuck on. If you cannot lower the jet enough, you may need to disassemble the carburetor to set the float height.
@@midwestmotoring Thank you
what is the situation for adjusting the idle air bypass on the Zeniths? brass screw and spring on the side of the carbs?
So the bypass valve is literally what it sounds like--it bypasses the throttle with enough vacuum and lets in fuel/air mixture. It's controlled by a spring pressing against a plate that seals off the flow. When the vacuum goes high enough to compress the spring, it opens the plate and lets fuel/air flow into the engine. You can adjust the tension on that spring by turning the adjustment screw (if there is one--if there's not, it requires disassembly).
The procedure I use is to:
1. disconnect the vacuum retard (if you have it), which should bring the RPM to about 1300 or so.
2. Start with the adjusting screw(s) turned counterclockwise (you'll know it's far enough since the RPM will be able to drop to 1300 instead of staying over 2000--which indicates the valves are "floating").
Turn the bypass valve clockwise until the engine speed jumps up abruptly (you're making it float on purpose).
3. Turn the valve counterclockwise until the RPMs drop back down to the 1300 where it was at.
4. Blip the throttle and watch the engine speed drop back down to 1300. If it stays high, the valves are still floating and you need to adjust it out another half turn until you can rev the engine and it returns to normal.
5. Back it out one more half turn to seat the valve, reconnect everything, and balance the carbs or adjust the slow idle speed on the carb(s) if necessary.
@@midwestmotoring . Ok. Not the one I'm speaking of. this one is a brass needle,
Ah, you mean the thick brass screw on the side with the tapered end. You can think of the floats as being the course mixture adjustment, the needle/jet as the fine adjustment, and the idle trim screw as the very fine adjustment. For most owners it's best to just leave this closed. I believe it's necessary to use a gas analyzer to tell the difference when making this adjustment. Someone else might have more information than I do, but the short version is that it's not necessary to adjust.
New to old British cars, I'm getting ready to restore a TR4. I was just going through the carbs last night. I've been building motorcycles for years, and am used to vacuum syncing. Is there a reason why an air flow meter should be more accurate in setting up a set of 175cd carbs? I noticed vacuum lines on both carbs I was thinking that was for this reason lol.
The vacuum lines on the carbs are not for syncing them. They drive the distributor advance/retard depending on the throttle position and load. An air flow meter is definitely more accurate, but you can do it with a bit of hose and just listen to the sound.
@@midwestmotoring I understand what they are for, but don't quite understand why they wouldn't be able to be used to balance the carbs. For motorcycles you adjust the butterflies so that the vacuum is even, but here your adjusting the butterflies to even inlet air velocity. I just am curious if this is more accurate or if it's doing something I don't understand or am overlooking.
You probably could use them... but I believe only one carb has a vacuum port. You'd need a set with vacuum ports both on the top or both on the bottom (one top, one bottom will not have the same signal).
How do you set time on a TR6 with Petronix ignition?
A timing light pointed at the crankshaft pulley timing marks is the most accurate way to time the engine with any ignition. If you're asking about static timing, my understanding is that Pertonix ignition systems can be static timed in the same manner as points ignition. Set the timing mark on the crankshaft pulley to the desired static timing position. Connect a test light to the switched wire running from the coil to the distributor (the one that is not the power wire) and ground the test light, then turn the ignition on and twist the distributor body counter clockwise until the light is out. Then turn it clockwise slowly until the light comes on. Lock the distributor down and check with a timing light for further tuning.
Hola !
I really learn and enjoy your videos. Your technical expertise and well versed tutorials make the difference. I have a question for you, if you’re so kind. I overhauled a set of strombergs for a friend this week. Step by step as you describe in your video. After installing them and doing the adjustments, etc the car revs up and stays in 1200 to 1400 rpms. I’ve checked for vaccum leaks, none, sticking linkages, good, and everything else that I can think of. The car in question is a 1970 Jaguar e- type. Any suggestions? Again, thanks for all the videos .
Felix Diaz
Puerto Rico
Sounds like the bypass valves aren't adjusted correctly. They are probably set with not enough pressure on the spring, so they're allowing fuel to bypass at too low an engine vacuum.
Thank you for your videos I have watched them many times and was able to get a 71 TR6 running again after it had been sitting for a few years. I started by changing the fuel pump, then when one of the carbs was leaking I rebuilt them. Later i noticed the vacum retard was leak and replaced that as well. I have the petronics ignition and have the appropriate coil.
Question now, is that in low RPM between 1500 and 2000 - when the car is on the road, I am getting back fire. Seems to be fire=ing into the carbs, because the pistons are blackened. I think I have looked at everything multiple time, but can't get the backfire to stop.
Do you have any suggestions where to focus? Thanks in advance for your reply
I suspect timing. Sounds like points out of adjustment, but you say you have a pertronix. My next guess would be with the distributor. It's pretty common that these don't advance/retard as they should. Check with a timing light and make sure you're getting full advance AND that it's retarding all the way back at low RPM. Your distributor may need a rebuild. If it does, let me know and I can help.
Yes very, very good info. That said when you are producing a teaching video consider borrowing a muffled Triumph even if your straight pipe baby needs a tune up. I've got a TR6 myself but i didn't make it thru the video because of the joyful noise.
Actually I did put on a new exhaust, which is a stock one. I think I did that before this video, but I'll make sure the sound level is better going forward. Thanks for the feedback!
I know this is a pretty old video but I have a question about where to start when reviving the old carbs on my barn find GT6. They had some issues when the car was still running about 15 years ago but since I've never really worked on carburetors before I'm pretty stumped on what to do.
You're in luck! The GT6 uses CD150 carburetors, which are very similar to the CD175s used on a TR6. This video should help: studio.ruclips.net/user/videowQaRvarG5oY/edit. If you've got a very early GT6, there might be some differences, such as adjusting from the bottom or some differences in how the choke works. By and large, though, it should be nearly the same.
I really appreciate you taking the time to make these
Glad to help. I'm hardly an expert, so the best news is that if I can do it so can everyone else!
The diapragm cover on the front carb is not fitted correctly. You have it 180' out. The alignment mark on the casting is is not aligned with the one on the carb body. The rear carb has the marks aligned correctly.
Wow, I'm not sure how I've missed that. Good catch! It's actually only 90 degrees out, rotated counter clockwise. Still... too much focus on the camera and not on what I'm doing. I'll head out to the garage now to fix it. Much appreciated.
MUCHAS GRACIAS POR EL VIDEO, ME SERA DE GRAN UTILIDAD,PUES EN ARGENTINA NO SON MUY VISTOS LOS STROMBERG,SE LOS ACABO DE INSTALAR EN UN MOTOR DE 8 CILINDROS L, en una bateria de 4 unidades,la llave para regular las agujas me la fabrique,lo que no tengo es el medidor de flujo,como lo puedo reemplazar,desde ya muchas gracias.
Glad it helped!
I'm a 78 TR7 with dual Strombergs. Do you have one, or is it pretty much the same as your TR6. I rebuilt the carbs now they seem out of tune and idle too high for one....thank you!
PS Tequila for me in gluten free California, though it's not a single carb 1975
They are pretty much the same. 1, make sure you loosen the throttle linkage when setting the idle so the carbs can be set independently. Also push the throttles closed to ensure nothing is sticking. 2, if you can't get the idle down no matter what you do, it's probably one of the bypass valves set too loose. I should like tequila as I'm half Mexican, but it's whiskey for me. ;)
,@@midwestmotoring Just like my cousin.Your better half is disguised, I'm an 1/8th N.A., BTW. I want to know about the two screws on the side of the carb.Is that mixture or the bypass valve? Is this something that is like an art form or can a rookie like me hack it. Maybe there is a good book on it. I'm getting the tools for the job, but getting it to pass smog....well maybe the shop with a gassalizer machine is what is best.Any recommendation and thanks for the reply. Brian
Anyone can work on these. It takes time and a few tools. If I know which screws you're referring to, one is in the bypass valve and the other just above the temp compensator. The one on the bypass valve controls how much vacuum is needed before the valve opens. It should only open at very high vacuum, so if your car is idling fine then don't touch it. If you can't get it to idle below 2500 or so no matter what you do... then suspect that screw. The other is an idle trim screw. As the engine wears in, it's slowly closed off. It's a very fine adjustment and normally you'll need a gas analyzer to even tell the difference. Just screw it in all the way and out maybe half a turn and it's good enough.
@@midwestmotoring Thank you. I think I'll look into your series,it seems to make a sense to me when you explain it.
That's the goal. Hopefully more classics end up on the road. If you get stuck and need help, just ask!
Very helpful, I had a MGB before with twin SUs, it was good fun. Now I have a Triumph Vitesse 1967 2 liters inline 6 cyc. with twin Zenith Strongberg Carbs which are running good. What is the tool you use to adjust the fuel richness?
That would be this guy: mossmotors.com/triumph-tr6-250/car-care-garage-tools/tools/tool-carb-adjusting. There are other vendors that sell the same thing, and they all vary slightly but do the same job. It's worth noting that only later Stromberg carburetors use this tool. The early ones adjust by a hex nut on the bottom of the carburetor, and for a year or so in the middle you may even find carburetors that are not adjustable--you have to disassemble them and physically move the needle.
Great video. Question I drove my 75 TR6 at a higher elevation (2400 ft) and stopped to enjoy the view. After about 10 minutes the car was hard to start and I had to use the choke to get going. Once I got back down to sea level it ran fine. Are the TR6 carburetors that sensitive? Thanks
Short answer, yes... though I'd expect a much larger altitude change than 2400 ft. Easy to fix though. If you know you're going high up and have any trouble, just keep an adjustment tool in your car. Wind the needles down a quarter to a half turn and keep on driving, then replace later when you're lower again. Technically though, it should run rich at higher altitude... not lean, so if the choke is what worked, you may have had a different issue such as flooding. Pulling the choke does add even more fuel, but also opens up the throttles too.
Thanks for the advice. Car is running great.
Good morning! I have a 1971 Triumph TR6. It has Zenith-Stromberg 175 CD carburetors installed. I have only owned this car for about two months. I noticed on my carbs the fuel inlet that is located on the upper left of the carb is left open(no fuel or even a fuel line). The fuel enters the carb on the lower right fuel inlet on both carbs only. I noticed in this video that you have fuel going to both sides of the carburetors. Should I have the left side receiving fuel as well? The car runs great without any issues although it does idle at about 1500 RPMs. What are your thoughts? Thanks, Randy Gibson, Atlanta, GA
Hi Randy, good question. That's not a fuel inlet, it's a vent. It should be connected to the charcoal canister. On some cars, this has been removed (for no good reason, really). In those cases, if it can't be easily reconnected, you should leave it to vent to the atmosphere as it is or it will leak. Good luck with the TR!
Oh, and the idle can be lowered by undoing the throttle stop screws a little at a time. I think I've got a video on tuning the carbs that might show that a little better. Hope that helps!
@@midwestmotoring Thank you for the quick reply. Like I said I have not had the car for long. It does not have a charcoal canister. The carburetor vents are just left open. I bought a cap for them. I think I will remove the cap and let them vent. As I finish the restoration I will probably add the canister back to make it more like the original 1971. I really appreciate your channel. I’ve learned a lot from you expertise. Thanks again. Randy
Hola Midwest. Felicitaciones por el video, es de gran utilidad. Estuve viendo el Link de Moss y venden una aguja 45 M que aclara que de gran altitud. La pregunta que te hago es ¿Que se considera gran altitud? ¿cuantos metros del nivel del mar?. Gracias.
Hola, y gracias para la pregunta. Lo siento--mi Espanol es terrible! No se si necesitas una aguja especial. Cuando estuve en Colorado con el Spitfire, solamente necesito poner mas rico--no necitaba partes especial.
Ahora en ingles:
Hi and thanks for the question. I'm sorry--my Spanish is terrible! I don't know if you need a special needle. When I was in Colorado in the Spitfire, I only needed to make it more rich--I didn't need special parts.
I hope that helps! Thank you for watching!
Thanks, your videos are very helpful as I work to revive a TR6 myself. What are your thoughts on the idle adjustment screw on the Strombergs?
Good question! Technically you're referring to what is (on most carbs) the idle trim screw. With Z-S carbs, the trim screw is the finest adjustment with the least amount of range. It will be difficult to find the proper setting without a gas analyzer, so you should just get as close as possible with the needle. The needle, then, is a slightly less fine adjustment. It's what you'll want to give a half a turn or so to when you go into the mountains, or what you should use when tuning the car after doing work. Finally, the course adjustment is the fuel floats. If you haven't got enough range in the needle travel, the float height (and remember there are 2 sides to the float!) may be off. The short answer is that I usually just screw in the idle trim screw all the way and ignore it.
Excellent video Wish I had su carbs on the tr6 like I have on the tr3 Nice job
Just put up another video talking about CD carbs. SUs and Strombergs are basically the same apart from some add ons that the strombergs have. I actually like them better in some ways.
Great video!
Thanks!
how do feel about weber 32/36 conversion for a Tr-6.
Just in general, I don't like the shape of the manifold. You're taking a side draft setup and putting a downdraft carburetor on it--but without much room, so it makes for some inefficient angles. As for the carburetors themselves, there's nothing wrong with them--but the Strombergs on a TR6 are definitely not the limiting factor when it comes to making power. Side draft Webers such as DCOEs are a different story. They have individual openings for each cylinder, and especially in a full-throttle situation can flow more. However, the engine in stock form simply can't pull that much air--so it's a waste without considerable upgrades such as raising compression, changing the cam, modifying the exhaust, and so forth.
This is going to be soooo useful this weekend! Thanks for creating this series.
Glad to be helpful!
Fabulous series on the Stromberg carburetors. Great to have gone to school class. Really appreciate that you simplify with a clear delivery and you’re not afraid to share the odd faux-pas. Combined with your ignition system videos I’ve got my 72 GT6 Mk3 running like it never had since i got it.
Did our own schooling on the Lumenition electronic ignition which had a blown IC, replaced for 50p :) One thing i got confused about in my car was i found it had a 12volt coil labelled for a ballasted system. I’d thought it was one or other. 12v non-ballasted or 6V ballasted. At moment I’ve replaced the coil with a 12v with primary resistance of 3.5ohm which matches the spec in the Haynes manual. But would be great to know how to double check if there is or is not a ballast resistor in situ. Any tips for that? Cheers Jim (Glasgow Uk)
Hmmm... So technically, in a points system with a ballasted ignition and the points closed, you have a complete circuit and can see a lower voltage than battery voltage. You'll get something like 8V instead of 12V. If you have a non-ballasted system then you'd see the full battery voltage rather than a reduced amount. This ONLY works with the points closed, since without the complete circuit you'll get battery voltage either way. You may be able to mimic closed points with an electronic ignition. For example, the new XR700 system I believe has an LED light that may indicate when the points would be open/closed (even though there are no points). Alternatively (and this is a question for en electrical engineer or some other qualified person), I believe most voltmeters show the AVERAGE voltage. So if the points are opening and closing (or if your electronic ignition is triggering the coil), you might see the average of 6-8V and whatever battery voltage is. If that's true, then pretty much any number a bit lower than battery voltage would indicate you have a ballasted system requiring a 1.5 ohm coil.
Thank you again. Sorry for tardy reply. Checked that out and I'm getting constant battery voltage levels and think can safely conclude that is an inflated system, the previous coil was incorrect. Think that's the ignition system all in good shape now and the repaired chip in the electronic ignition seems to be holding up well.
Getting a little backfiring under deceleration but the car hasnt run for quite some time so plan is to get a few hundred miles and a few trips under the belt and revisit the timing and carb tuning. Thanks again for your videos.
@@jimdarroch2136 I'm happy to help. The backfiring, by the way, can be down to a couple reasons. First off, if you have bypass valves on Zenith Stromberg carburetors, they might be closed off to make them non-functional. A lot of owners have done this, but it makes the car prone to backfiring when letting off the throttle. You might also find that the timing is changing under deceleration. Maybe a weight is sticking inside the distributor or a vacuum capsule isn't working properly? I'd suspect the weights first since the vacuum only moves the timing a few degrees.
Midwest Motoring cheers. I'll monitor it for a bit and check the bypass valve in case prior owners did this. I'll be ready to strip the distributor. Saw a helpful video of that somewhere 😊. I have added oil already. 👍
Thank you. It is no longer a mystery ....
I'm still thwarted now and again, but at least these days I always figure it out and just feel stupid that it took so long.
Thank you for the valuable lesson.
Happy to help! Thanks for watching!
thank you for your time great explanation
Glad it was helpful!
Really helpful thank you sir
Glad to be useful!
Nice demo the only thing I do different is that I blip the throttles when tuning them.
Ralph, that's an excellent point. I should have done that, and it's the correct thing to do in order to clear everything out.
@@midwestmotoring at what point(s) during the process would you blip the throttle?
@@GregSchnittger just generally you don't want to let the engine sit idling for too long while tuning it. You'll get false readings. Best to hit the throttles and then let the RPMs settle just before you raise the piston to check the mixture.
After cleaning my plugs my 74 TR6 has a dead miss and bogs down in acceleration, changed plugs no diff. What should I test?
Check the oil in your carburetors. Classic symptom of low oil in the dashpots.
@@midwestmotoring they were low, but i topped them off, and still have the same issue.
Was the car running fine before? In other words, the car had no issues, you pulled the plugs and put them back, and suddenly the car didn't run right? If so, it could be a coincidence but suggests the plugs are at fault. Did you use the correct type? What's the gap set at?
Also, did you pull the wires? Check each one and verify the firing order. Was the distributor loose?
I should also ask... what prompted you cleaning your plugs?
awesome job.....thankyou.
Thanks for watching!
Thanks for sharing.
Happy to help!
Great video!
Thanks!
Thanks again great video.
I'm happy it's helpful! Let me know if there is anything else you would like help with!
@@midwestmotoring Hi there is one thing, at some stage could you do a video on crankshaft end play, how to measure it and how to fix the problem with the motor in the car (TR6) Many thanks
@@darrenfechner5613 there is a video on crank end play. I think it's part 1 of getting the TR6 back on the road. I didn't need to show the repair but I've got the Spitfire engine out and will show the process there as well.
I"ll have to get a timing light and a dwell meter! Do you have any plans on doing a video on a coolant flush and refresh for the TR6/GT6 ? I think i read there's something in the head you need to clean out with a wire?
That I'm not sure about. I'm guessing the wire may help to loosen silt in the cylinder head, but that may be necessary mainly when new (to clear out casting bits) and when the maintenance hasn't been done (i.e. the coolant and oil haven't been changed and have left solid gunk inside). I'd recommend having a machinist do that, as you should no doubt have the surface machined if you're going that far. Good question! Thank you!
Excellent video !! I’ll surely watch it again when I’ll be adjusting my carbs on my Triumph GT6 !
You talked about early and late Stromberg carbs concerning the adjustment; do you consider CD150 Stromberg (as fitted on MK2 GT6) to be early or late ?
Good question. It could be either since I'm not sure when they made the change and you may or may not have the original carbs on your car. If there is a hex nut on the bottom, then that will be the adjustment point. Later carbs have a simple brass plug or a slotted screw-in plug on the bottom. There will not be a hex nut. A quick peak at your carburetors should tell you which you have.
@@midwestmotoring great thank you for the reply !