Night wrencher, great video. I have 4 corner system and having issue on the passenger side mixture screws. I have Holley 670 with vacuum secondary and electric choke. When primary mixture screw is seated all the way in, it actually picks up more rpm. Car will not stall or die. If I turn the mixture screws out no matter how many turns, idle will drop to 800 rpm and stays constant Float level is about 1/8th inch below the middle on the see through window. And of course, all plugs on the passenger sides are black. I called Holley tech and they weren’t much of a help. They said cork gasket could be damaged. I checked the cork gasket with mixture screw out and it was fine. Friend of mine told me to try cleaning air bleeds with carb cleaner and compressed air well as mixture screw hole. After that, seat all 4 mixture screws in and main idle screws all the down to kill the motor. Then, back out one half on all mixture screw and 1 turn clockwise on main idle screw. Turn the engine on and try tuning again see passenger side mixture screw stalls or shut the engine off when turned all the way in. What do you think? Car has big cam so using vacuum gauge is almost impossible. Thanks man
Hey man, I was at SEMA all last week and forgot to reply. I would try to tune it when the engine is already hot and the carb is heat soaked for best results. At idle, if all 4 screws are turned all the way ithen , the engine should immediately die. If you're closing the idle mixture screws and the RPM is picking up then I would look for an internal fuel leak like in the power valve that chasing is a'lowing fuel to get bypassed into the throat. After its does like its supposed to when all 4. With big cams like that, RPM is your own point of reference but it will never run like OEM smooth due to the nature of the carb.
great video! I just installed a holley 4160 on my ford 460 and I've been struggling with getting it to idle correctly. hopefully I'll be able to get it right using this info.
@@NightWrencher yeah. I was trying to get it all tuned. This video was very helpful. But my truck is having a weird backfire issue out the exhaust now. But definitely thanks for the video. Got my new carburetor dialed in a bit more.
You have about 2-3 turns before the t slot is over exposed. If you idle is set up correctly, you should be be 1/2 to 1 full turn in. If you need more than that, you need more timing, idle mix isnt right, or your cam is too big so you need 4 corner idle and need to open the secondaries
Another note, with electric choke, if your high idle screw is in too far, as in all the way like mine was, it will not allow your curb idle to be set properly. You may think that the choke system has nothing to do with these adjustments because you are doing it when its hot, but it does. Your high idle adjustment holds open the butterfly just a tickle on choke. If it doesn't kick out all the way after warm, it will continue to hold that butterfly open at idle, thus exposing your transfer slots too much. This will render your curb idle and idle mixture screws useless. It will cause surging at idle and cause a stumble off idle as well. You should be able to kill the engine by turning the curb idle out too much. If you can't, theres a problem. Once your curb idle is set, you should be able to kill the engine by screwing in the idle mixture screws all the way. If this doesn't happen, your engine is recieving fuel from somewhere it should not be(ie: transfer slots that are too exposed) On the other side of the spectrum, make sure your choke butterfly is opening all the way when hot. If this doesn't happen, you will be trying to adjust everything while slightly choked. I am aware other things may cause these same symptoms, this is just one example of tail chasing that I experienced. Hopefully this helps someone as I beat my head against the wall trying to figure this out. This was on a 4160 carb that I got for free that was "running when parked" lol
Hey I asked for your help on drilling or adding the rear block idle screws to a block that didn’t have them bc I was mistakenly given the wrong one:we it turns out after looking at it more Quick Fuel drills,taps and fills with Allen screw so all I have to do is replace with proper screws.cool beans that was easy enough but thanks for being responsive.
Thanks so much for this info...super helpful! Quick question. When I put on my carb I noticed my intake manifold had some residual gasket material along the bottom plane just splattered there from when the engine builder put everything together. Could this effect performance as far as flow?
I've never seen gasket material stuck to the intake plane but I have seen it stuck on the carb flange. If its inside of the intake, I would try to take it off so it doesnt fall into the cylinders. Aside from that, it shouldnt affect flow.
Thats a good idea! I've seen them around for a few years but have never tried them personally. I've read mixed reviews on them so I've been hesitant to try them out myself.
NightWrencher yes me too but they look like they work ! Hopefully you will test it out , apparently only certain shooter will work and I’ve noticed a different ini Holley and quick fuel , quick fuel nozzles are higher then Holley also
@@sharons9367 Another big thing is booster type. Down leg and annular boosters crash against the pump shot just like the powerblast plates do but the straight leg boosters like those in the economy holleys do not so the plates effectiveness might differ depending on what carb it gets installed on.
A lot of times yes because thats usually where I end up but its not a solution for every carb. Some carbs have wanted a quarter turn or 3/4 of a turn so it just depends
@@NightWrencher 👍 yep... I did this to my double pumper and it was so much easier to tune that way... But like You say it is based on what the engine needs. Thanks for the reply and shared knowledge.
The part I’m still confused about is after you do all of this stuff, where does the setting the transfer slot to a square come in to play? I was under the impression that you want to set the transfer slot to a square and then fine tune the idle with the idle mixture and the timing. If you’re doing all this aren’t you losing your transfer slot tuning? Thanks so much!
The thing about a square transfer slot is more of a general guideline to prevent you from giving it too much idle. A square transition on a 302 wont be the same RPM as say a 427 so really you should be going down as much as you can while adjusting the idle screws to compensate. Hope this makes sense
For Idle, it doesn't matter. For street tuning, its optional. The only thing that can happen is if you tune without the filter and then install the filter, the engine might run a hair richer
I know how to adjust it,I went to jegs and they gave me the wrong metering blocks for the rear and I need instruction on drilling and adding the adjuster.they’re quick fuel billet and the spot is there and I could likely do it but hopefully I can find a little help to be sure,thanks
There are 2 spots where you can run them but the top one is easier. I believe it takes an 8-32 tap into the large fuel passage on the top corners of the metering blocks. No drilling required. I'll make a video on it 👍
Is this pretty much how you adjust all the hollies with the four different judgment points? Do I need to start with the curb idle screw all the way in/down?
Its an easy way to do it with 4 corner idle carbs. The point of running in the speed screw is just to keep the rpms up and give you a good starting point. 2 corner idle is the same way but with just the front 2 screws
You screw down the speed screw a few turns and screw out the mix screws to 1 full turn out and then start the tuning like in the video. The real reason to turn it in is to keep the engine from stalling
I have a regulator with perfect pressure I have float bowls set perfect brand new Holley and I’ve adjusted the air fuel mixture screws to idle perfect but when I drive and hit the gas a tad tk hard it backfires and when I come to a stop and take off even slowly it backfired
@@NightWrencher I’m not sure I’m very scared to fool with the timing Becuase it ran great before the carb problems which was only some months ago but it also dies when coming tk a stop if not backfires when I h the gas
I would check that first before anything else. Timing has to be dead on before making any changes to a carb. I'll make a video going through it so you have something to refference
I have changed spark plugs wires , new carburetor electric fuel pump all gd stuff but still something is wrong the timing was checked but it backfires at high rpm any thoughts
What jets would be a good starting point for my mighty demon? It's on my 6.0 with f35 cam 706 head. It won't idle for shit. I've got the 4 screws out 1.5 turns just don't notice any change by turning them in or out
Jetting does not affect idle quality. If you turn all 4 screws all the way in, the engine should die. If it doesnt die, then your throttle is too far open or you have an internal fuel leak
Hey nightwrencher great vid. I tried this on my Holley double pumper and got the idle nice and smooth. Best idle I ever had. Here’s the kicker. When I tried to take it out for a ride it stumbles pretty hard. I’m scratching my head on this. Any idea?
Yeah its pretty normal when leaning out the idle, you need to compensate in other areas to fill in the gaps. Chances are your IFRs are too small or your accel pump shot is too small. Just depends on when exactly it hesitates
What is a good idle AFR if your running ported vac with no advance from the can? . I always would run full manifold and add around 6-12 degrees so I would idle at 22 or so and it wanted a rich AFR around 12:50 if I tried going up or down it wasn't happy . Usually I would need to jet up a size or 2 with ported since withouts the extra timing it can run up in the 14"s at idle and despite the controversy between full manifold and ported I'm kinda thinking why these auto makers did this ported thing . Being able the idle at a perfect 14.with no timing on ported put a smile on mother nature's face 😋. Although what the common AFR for ported I'm not in tune .
I'm going to have to make a video on this because a few people have asked me about it. Typically what I like to do is set the base timing at 13-15 for better starts and curve the distributor so that the advance comes in really fast and early. Qith that being said, you could back off the distributor to a lower base timing and run manifold vacuum for the advance as well. Typically you should be able to run a leaner mixture easier with more timing so I'm not sure why youre not able to get above 12.5 on manifold. What plug gap are you running and what is you base timing?
@@NightWrencher I'm at 10-12 base timing on 91 octane Pertronix 3 dist says it gives it 24 but I only had 30 total . If I bump up to 14 initial or more it thumps alot and shakes using full manifold so I settle for the 30 total and use the vacuum advance for the rest all in at 3k , that's around 40 total at 3 k with full manifold . With that setting it runs pretty good although it don't like a lean mix like 1350 idle AFR I can do 13 but it will shake and stumble.. Now ported thats totally different I can go 14 idle and it will run fine although starting its a run on kinda start . AFR in the 13:0 13;20-50 seems better ported I can also go to 14 initial with no issues to get the 32-34 total on ported I switched today but Im thinking the carb I bought on offer up someone drilled out some ports next to the IFR and that's why I can't tune it easy , I ordered a new one for 38 bucks a video would be great 😃👍 on the difference in tuning from full manifold vs ported and how they differ from one another then viewers like me can choose which one meets there performance needs 👍.
@@NightWrencher well I had to really bump up the fuel to keep it from stumbling I bought it new from a guy on offer up . First thing I noticed after really looking at it the squirt nozzle was a 25 ? It cam with a #31 then looking at the metering block I'm told those should be drilled out to 0.06 ? The hole has a brass incert on one side the other is punched in or missing and on the right there is a feed hole next to the IFR and it's really big and looks like that's been drilled out ? . So had to richen up the take off acceleration #35 squirter or it would go up to 16 AFR and a few pops at slow speeds .
What I take away from this is to tune the mixture screws for what the engine wants. I've always heard to keep the mixture screws exactly the same, is that not necessary?
On a single plane or dual plane with an open spacer, you should probably keep them close but on a dual plane or dual plane with 4 hole spacer, tune for what the engine wants because each corner will be different. Keep them the same at first but the fine tuning will be different for each corner
@@NightWrencher mine is a factory iron quadrajet intake with an open spacer. 4160 with primary adjustments only. Keeping the adjustments identical, i find that I can't get it to idle much leaner than 12afr without it running rough and popping like a machine gun out of the exhaust on deceleration (manual trans). Id like to get it to idle leaner, but at a loss as leaner would also just make the popping worse as well.
In order to run leaner mixes you'll need a good ignition system that can run wider spark plug gaps. You'll also need to make sure you have enough compression to light off the mix too. Give the engine what it wants, and go from there.
@@NightWrencher fair enough. Gaps are currently at .55 I believe. Is the popping on decel fairly normal as well as the afr for idle (I've no baseline for whats normal on carbureted engines)? The only other question I have, is for some reason I notice slight surging when climbing hills/grades. Almost like the secondaries butterflies are doing something weird? I see the afrs go richer when it surges. Thanks for the help btw.
@@asus6983 a lot of what you're describing is timing related. What engine us the carb on? A lot of old cars used to use dashpots to keep the throttle from slaming shut and prevent popping on decel. Open exhaust also causes that as well as exhaust leaks. Rich Surging on full throttle uphill is either too rich secondaries or PVCRs too big. Vacuum secondaries are hard to tune because the secondaries move on their own. I would install a vacuum gauge and see if you can cause the rich condition on command.
The air cleaner acts like a slight restriction causing the mix to richen up. Thats why engines are not dynod with them on and a lot of race cars dont either
Did the needle and seat get stuck? If it did, you can twist it back out with needle nose pliers or locktite on a bolt with the same thread pitch or the lock screw.
@@NightWrencher interesting, Did you buy it new, somone might have already leaned out the jets in my humble opinion the "street" and race demons are always rich compared to holleys in fact if you look it up a 750 demon pulls around the same air as a holley 850 anywho happy wrenching
Thank you for your Time and efforts making this video.. Best carb tunning video on RUclips.
Thank you sir! That means a lot!
This is an excellent video covering the subject of idle fuel mixtures. Thank you for taking the time to share this!
My pleasure 👍
Glad you did it while running. Also visiting the rear pipes helped also.
Thanks man, hope you enjoyed it 👍
Night wrencher, great video. I have 4 corner system and having issue on the passenger side mixture screws. I have Holley 670 with vacuum secondary and electric choke. When primary mixture screw is seated all the way in, it actually picks up more rpm. Car will not stall or die. If I turn the mixture screws out no matter how many turns, idle will drop to 800 rpm and stays constant Float level is about 1/8th inch below the middle on the see through window. And of course, all plugs on the passenger sides are black. I called Holley tech and they weren’t much of a help. They said cork gasket could be damaged. I checked the cork gasket with mixture screw out and it was fine. Friend of mine told me to try cleaning air bleeds with carb cleaner and compressed air well as mixture screw hole. After that, seat all 4 mixture screws in and main idle screws all the down to kill the motor. Then, back out one half on all mixture screw and 1 turn clockwise on main idle screw. Turn the engine on and try tuning again see passenger side mixture screw stalls or shut the engine off when turned all the way in. What do you think? Car has big cam so using vacuum gauge is almost impossible. Thanks man
Hey man, I was at SEMA all last week and forgot to reply. I would try to tune it when the engine is already hot and the carb is heat soaked for best results. At idle, if all 4 screws are turned all the way ithen , the engine should immediately die. If you're closing the idle mixture screws and the RPM is picking up then I would look for an internal fuel leak like in the power valve that chasing is a'lowing fuel to get bypassed into the throat. After its does like its supposed to when all 4. With big cams like that, RPM is your own point of reference but it will never run like OEM smooth due to the nature of the carb.
The greatest video I have ever seen about tuning a carb. What is your fuel pressure..🖒
Thanks man! I keep it right around 5.5-6psi
Thank you for the info i got 2 demon carburetor s i bought one for 50 it works good intalled it in my 68 Buick Riviera GS
Thats awesome man, glad it worked out!
Great Content man appreciate it so much can't wait to go out there and try this
great video! I just installed a holley 4160 on my ford 460 and I've been struggling with getting it to idle correctly. hopefully I'll be able to get it right using this info.
Hopefully! Good luck!
This will be fun with my Bronco. I’ll be climbing a ladder every time.
It was fun on my truck. Lifted 4" on 35" tires 🤣
@@NightWrencher yeah. I was trying to get it all tuned. This video was very helpful. But my truck is having a weird backfire issue out the exhaust now. But definitely thanks for the video. Got my new carburetor dialed in a bit more.
Haha. Why get mad at your dog? He wants to also learn how to adjust the air/fuel mixture on a Holley just like myself. Nice video thanks.
Because hes always begging me for people food 🤣
@@NightWrencher Guess he is not a wrench head after all. Just like my dog, always wanting treats.
No hes not 😂
Exactly what I needed ! Will try it out tomorrow !
Good luck! I just did it in my latest video on a firebird street tune so feel free to check it out!
What about proper transfer slot exposed? How do u tell after messing with idle?
You have about 2-3 turns before the t slot is over exposed. If you idle is set up correctly, you should be be 1/2 to 1 full turn in. If you need more than that, you need more timing, idle mix isnt right, or your cam is too big so you need 4 corner idle and need to open the secondaries
Another note, with electric choke, if your high idle screw is in too far, as in all the way like mine was, it will not allow your curb idle to be set properly. You may think that the choke system has nothing to do with these adjustments because you are doing it when its hot, but it does. Your high idle adjustment holds open the butterfly just a tickle on choke. If it doesn't kick out all the way after warm, it will continue to hold that butterfly open at idle, thus exposing your transfer slots too much. This will render your curb idle and idle mixture screws useless. It will cause surging at idle and cause a stumble off idle as well. You should be able to kill the engine by turning the curb idle out too much. If you can't, theres a problem. Once your curb idle is set, you should be able to kill the engine by screwing in the idle mixture screws all the way. If this doesn't happen, your engine is recieving fuel from somewhere it should not be(ie: transfer slots that are too exposed) On the other side of the spectrum, make sure your choke butterfly is opening all the way when hot. If this doesn't happen, you will be trying to adjust everything while slightly choked. I am aware other things may cause these same symptoms, this is just one example of tail chasing that I experienced. Hopefully this helps someone as I beat my head against the wall trying to figure this out. This was on a 4160 carb that I got for free that was "running when parked" lol
Very helpful, thanks man!
Youre welcome!
Hey I asked for your help on drilling or adding the rear block idle screws to a block that didn’t have them bc I was mistakenly given the wrong one:we it turns out after looking at it more Quick Fuel drills,taps and fills with Allen screw so all I have to do is replace with proper screws.cool beans that was easy enough but thanks for being responsive.
Thats awesome man, good to hear it worked out 👍
Wow I really really needed this info 🙏🏾
👍
Thanks so much for this info...super helpful!
Quick question. When I put on my carb I noticed my intake manifold had some residual gasket material along the bottom plane just splattered there from when the engine builder put everything together. Could this effect performance as far as flow?
I've never seen gasket material stuck to the intake plane but I have seen it stuck on the carb flange. If its inside of the intake, I would try to take it off so it doesnt fall into the cylinders. Aside from that, it shouldnt affect flow.
I would like you to do a review on the Thompson performance powerblast plate
Thats a good idea! I've seen them around for a few years but have never tried them personally. I've read mixed reviews on them so I've been hesitant to try them out myself.
NightWrencher yes me too but they look like they work ! Hopefully you will test it out , apparently only certain shooter will work and I’ve noticed a different ini Holley and quick fuel , quick fuel nozzles are higher then Holley also
@@sharons9367 Another big thing is booster type. Down leg and annular boosters crash against the pump shot just like the powerblast plates do but the straight leg boosters like those in the economy holleys do not so the plates effectiveness might differ depending on what carb it gets installed on.
Awesome Video...
Do You think its ok and easier to 1/2 turn the rear and adjust the max vacuum and best idle only from the front ?
A lot of times yes because thats usually where I end up but its not a solution for every carb. Some carbs have wanted a quarter turn or 3/4 of a turn so it just depends
@@NightWrencher 👍 yep... I did this to my double pumper and it was so much easier to tune that way... But like You say it is based on what the engine needs. Thanks for the reply and shared knowledge.
Awesome video
I appreciate it!
The part I’m still confused about is after you do all of this stuff, where does the setting the transfer slot to a square come in to play? I was under the impression that you want to set the transfer slot to a square and then fine tune the idle with the idle mixture and the timing. If you’re doing all this aren’t you losing your transfer slot tuning? Thanks so much!
The thing about a square transfer slot is more of a general guideline to prevent you from giving it too much idle. A square transition on a 302 wont be the same RPM as say a 427 so really you should be going down as much as you can while adjusting the idle screws to compensate. Hope this makes sense
good info, thanks.
Thanks for watching! I hope it helps!
Great info brother....
Thanks a lot big tom!
I was always taught to do carb adjustments with the air cleaner on, no?
For Idle, it doesn't matter. For street tuning, its optional. The only thing that can happen is if you tune without the filter and then install the filter, the engine might run a hair richer
I know how to adjust it,I went to jegs and they gave me the wrong metering blocks for the rear and I need instruction on drilling and adding the adjuster.they’re quick fuel billet and the spot is there and I could likely do it but hopefully I can find a little help to be sure,thanks
There are 2 spots where you can run them but the top one is easier. I believe it takes an 8-32 tap into the large fuel passage on the top corners of the metering blocks. No drilling required. I'll make a video on it 👍
Nice video 💪🏾💪🏾💪🏾
Thank you sir!
Is this pretty much how you adjust all the hollies with the four different judgment points? Do I need to start with the curb idle screw all the way in/down?
Its an easy way to do it with 4 corner idle carbs. The point of running in the speed screw is just to keep the rpms up and give you a good starting point. 2 corner idle is the same way but with just the front 2 screws
@@NightWrencher so screw down the speed screw as well when I set the 4 adjustment points as well?
You screw down the speed screw a few turns and screw out the mix screws to 1 full turn out and then start the tuning like in the video. The real reason to turn it in is to keep the engine from stalling
I have a regulator with perfect pressure I have float bowls set perfect brand new Holley and I’ve adjusted the air fuel mixture screws to idle perfect but when I drive and hit the gas a tad tk hard it backfires and when I come to a stop and take off even slowly it backfired
What is you base timing set at?
@@NightWrencher I’m not sure I’m very scared to fool with the timing Becuase it ran great before the carb problems which was only some months ago but it also dies when coming tk a stop if not backfires when I h the gas
I would check that first before anything else. Timing has to be dead on before making any changes to a carb. I'll make a video going through it so you have something to refference
I want mine to run like that ! Same carb too
It just takes a little bit of time but anyone can do it
I have changed spark plugs wires , new carburetor electric fuel pump all gd stuff but still something is wrong the timing was checked but it backfires at high rpm any thoughts
You said timing was checked but you didn't say where it was at. What is your base timing and what is the max and at what RPM?
What jets would be a good starting point for my mighty demon? It's on my 6.0 with f35 cam 706 head. It won't idle for shit. I've got the 4 screws out 1.5 turns just don't notice any change by turning them in or out
Jetting does not affect idle quality. If you turn all 4 screws all the way in, the engine should die. If it doesnt die, then your throttle is too far open or you have an internal fuel leak
Hey nightwrencher great vid. I tried this on my Holley double pumper and got the idle nice and smooth. Best idle I ever had. Here’s the kicker. When I tried to take it out for a ride it stumbles pretty hard. I’m scratching my head on this. Any idea?
Yeah its pretty normal when leaning out the idle, you need to compensate in other areas to fill in the gaps. Chances are your IFRs are too small or your accel pump shot is too small. Just depends on when exactly it hesitates
What does it means when there’s a strong fuel smell coming from the tail pipe? I have a small block 350.
Sounds like your running too rich. Running too lean also causes a harsh smell and big cams do the same. Have you already reset your idle mixture?
Do the 4 corner idle screws control fuel? I thought it was air that it controlled?
Yes, the idle screws control fuel. You turn it in to block fuel, and turn them out to add fuel.
@@NightWrencher awesome. I’m not sure why I thought those were normally air screws. Currently doing this on my .060 318
Sweet, it should work exactly the same as this video then. You could follow it almost exactly and you should be able to dial yours in.
@@NightWrencher thank you. I was having some trouble with white/blackish kinda smoke at idle n figured it had to be my 4 corner idle screws
@@NightWrencher out of the box the brawler was .75 of a turn out all the way around on the 4 corner idle screws
What is a good idle AFR if your running ported vac with no advance from the can? .
I always would run full manifold and add around 6-12 degrees so I would idle at 22 or so and it wanted a rich AFR around 12:50 if I tried going up or down it wasn't happy .
Usually I would need to jet up a size or 2 with ported since withouts the extra timing it can run up in the 14"s at idle and despite the controversy between full manifold and ported I'm kinda thinking why these auto makers did this ported thing .
Being able the idle at a perfect 14.with no timing on ported put a smile on mother nature's face 😋.
Although what the common AFR for ported I'm not in tune .
I usually tried for 13"s but it's very hard to get 12:50 on ported .
I'm going to have to make a video on this because a few people have asked me about it. Typically what I like to do is set the base timing at 13-15 for better starts and curve the distributor so that the advance comes in really fast and early. Qith that being said, you could back off the distributor to a lower base timing and run manifold vacuum for the advance as well. Typically you should be able to run a leaner mixture easier with more timing so I'm not sure why youre not able to get above 12.5 on manifold. What plug gap are you running and what is you base timing?
@@NightWrencher I'm at 10-12 base timing on 91 octane Pertronix 3 dist says it gives it 24 but I only had 30 total .
If I bump up to 14 initial or more it thumps alot and shakes using full manifold so I settle for the 30 total and use the vacuum advance for the rest all in at 3k , that's around 40 total at 3 k with full manifold .
With that setting it runs pretty good although it don't like a lean mix like 1350 idle AFR I can do 13 but it will shake and stumble..
Now ported thats totally different I can go 14 idle and it will run fine although starting its a run on kinda start .
AFR in the 13:0 13;20-50 seems better ported I can also go to 14 initial with no issues to get the 32-34 total on ported
I switched today but Im thinking the carb I bought on offer up someone drilled out some ports next to the IFR and that's why I can't tune it easy , I ordered a new one for 38 bucks a video would be great 😃👍 on the difference in tuning from full manifold vs ported and how they differ from one another then viewers like me can choose which one meets there performance needs 👍.
Yeah, its wierd, it shouldnt act like that. Let me know how it works with the new one 👍
@@NightWrencher well I had to really bump up the fuel to keep it from stumbling I bought it new from a guy on offer up .
First thing I noticed after really looking at it the squirt nozzle was a 25 ? It cam with a #31 then looking at the metering block I'm told those should be drilled out to 0.06 ? The hole has a brass incert on one side the other is punched in or missing and on the right there is a feed hole next to the IFR and it's really big and looks like that's been drilled out ? .
So had to richen up the take off acceleration #35 squirter or it would go up to 16 AFR and a few pops at slow speeds .
What I take away from this is to tune the mixture screws for what the engine wants. I've always heard to keep the mixture screws exactly the same, is that not necessary?
On a single plane or dual plane with an open spacer, you should probably keep them close but on a dual plane or dual plane with 4 hole spacer, tune for what the engine wants because each corner will be different. Keep them the same at first but the fine tuning will be different for each corner
@@NightWrencher mine is
a factory iron quadrajet intake with an open spacer. 4160 with primary adjustments only. Keeping the adjustments identical, i find that I can't get it to idle much leaner than 12afr without it running rough and popping like a machine gun out of the exhaust on deceleration (manual trans). Id like to get it to idle leaner, but at a loss as leaner would also just make the popping worse as well.
In order to run leaner mixes you'll need a good ignition system that can run wider spark plug gaps. You'll also need to make sure you have enough compression to light off the mix too. Give the engine what it wants, and go from there.
@@NightWrencher fair enough. Gaps are currently at .55 I believe. Is the popping on decel fairly normal as well as the afr for idle (I've no baseline for whats normal on carbureted engines)? The only other question I have, is for some reason I notice slight surging when climbing hills/grades. Almost like the secondaries butterflies are doing something weird? I see the afrs go richer when it surges. Thanks for the help btw.
@@asus6983 a lot of what you're describing is timing related. What engine us the carb on? A lot of old cars used to use dashpots to keep the throttle from slaming shut and prevent popping on decel. Open exhaust also causes that as well as exhaust leaks. Rich Surging on full throttle uphill is either too rich secondaries or PVCRs too big. Vacuum secondaries are hard to tune because the secondaries move on their own. I would install a vacuum gauge and see if you can cause the rich condition on command.
How does putting the air cleaner on effect the tune (balance) of carb.
The air cleaner acts like a slight restriction causing the mix to richen up. Thats why engines are not dynod with them on and a lot of race cars dont either
I think I over adjusted the float too low and now I can't get it to fill up again. Help please
Did the needle and seat get stuck? If it did, you can twist it back out with needle nose pliers or locktite on a bolt with the same thread pitch or the lock screw.
It’s a new carb so not sure if that would be the case but I’ll double check tomorrow.
If you screwed in the needle and seat too far, You won't be able to pull it back out with the Lock nut
Ok then that must be it. Thanks and great videos keep it going. I’ll keep you posted.
You were correct sir, i had screwed it in to far.
cool boxer
Thanks man 👍
That's a demon a race carb its rich from factory
Its actually not a Race Demon, its an older street demon but on the contrary, it used to run lean before I started tuning it.
@@NightWrencher interesting, Did you buy it new, somone might have already leaned out the jets in my humble opinion the "street" and race demons are always rich compared to holleys in fact if you look it up a 750 demon pulls around the same air as a holley 850 anywho happy wrenching
Actually, it was the IFRs that were lean. The IFRs feed the idle screws so both the transition and idle were lean