IVE BEEN MESSING WITH HOLLEYS FOR YEARS, READ ALOT OF STUFF ON THEM TOO, BUT MY MAN, YOU TOOK IT TO ANOTHER LEVEL, VERY UNDERSTANDABLE FOR THIS OLE COUNTRY BOY, THANKS ALOT, YOU ARE GREAT AT TEACHING AND VERY KNOWLEDGEABLE.
Thank you Norm and the Summit Racing team for taking the time to make these videos. They are more help than you will ever know! Great job and keep em coming!
Thanks for the great videos. I have learned more about carburetors watching your videos .I think you are a good teacher with a sense of humor to boot. Thanks.
Greetings sako1952, Humor is good - never take yourself too seriously. The more you know about something the more liberal you should be about sharing that knowledge. Thank you for the kind words. -Norm
With rare exception… if, in your original tuning you were able to dial in your idle circuit correctly then changing the jets and or working on the main circuit should not constitute the need for an additional idle mixture screw adjustment.
made this so easy to understand, I was surprised. thank you great video! ive been having carb question about tuning, but I now have a level of understanding
The videos was very helpful for understanding things. But I believe you misspoke when talking about the Venturi. You go from hight pressure low VELOCITY (not volume), to a low pressure high velocity, and back again. I believe this is what it is supposed to be
Thank you, Thomas. We really appreciate your kind words. Please let us know if you have any additional questions! We have two more Holley carb videos coming soon so stay tuned :)
It may be helpful to understand total pressure and its components static and dynamic pressure. Total pressure equals static pressure + dynamic pressure. Dynamic pressure is a function of velocity. Specifically velocity squared. When the video presents HiV and LOV it is velocity. Since total pressure is a function of both static and dynamic pressure, when velocity increases because cross sectional area decreases in the venturi (when flow is unchoked), the dynamic pressure is increasing causing a decrease in static pressure because total pressure is constant. If a circuit has one end attached to the high dynamic (high velocity) pressure and the other to low dynamic pressure (atmospheric pressure), there will be flow high to low.
Ron, Going for a drive while watching a vacuum gauge sounds like tuning the power circuit (Power Valve). Generally I would use a vacuum gauge for tuning the idle circuit, the power circuit and possibly as an aid in tuning the secondary side of a vacuum secondary carburetor. Ideally you would want to know the vacuum that the engine is producing at idle, at or near a mid-range steady-state cruise, and at W.O.T. and make your adjustments from these findings. Do you have any specifics? Let me know.
this guy is awesome. so informational. its very helpful how he breaks it down and explains it all piece by piece. but i have a quick question after changing the main jets do you have to go back and re-adjust the idle air screws?
I have 62 cc/minute front and rear max vaccum at idel. I can let out the clutch and move the truck around. I need to find a 600cfm choke or send it to Summit for repair. Or get the Atomic system.
I have a 427 S/B 520HP with a 850 quick fuel carb. The youtube vids iv seen tell me to set mixture screws to start at 1an a half to 1an quarter turns an turn out to fine tune. My best vac occurs at less than 1 turn out am i missing something any help please
hi ron i have a 1150 holley dom, i can,t get the .015 on my carb, i tryed every way but not having any luck, can you help me. jimmy sorry its on the pump, on both
Hi! Thank you for the question. Our tech department asked if you could give us a call at 1-330-630-0240. We look forward to your call. Thanks for watching!
Im looking at tuning my mains in a 1050 dominator. Im getting this is a street car you are tuning for? I cant exactly cruise down the road in my race car. How would i find the starting point on the primaries since it is pretty much wide open when I run it? Thanks for any help.
Thanks for the video!! Why does my setup like squared jets, meaning nearly the same all around. There’s a power valve in the primary but none in the secondary. 4150 650 DP. Thanks!
On average, a power valve makes up for approximately 5-7 jet sizes. There are a couple of reasons why your set up could be a little different. Float level, emulsion sizes in the metering block, high-speed air bleed differences to name a few. You may be a little rich on the primary side, and a leaner secondary side balances it out under WOT. If you suspect this, try disconnecting the secondary linkage and tune the primary side mixture for 12.5 -13.0 (assuming your running gasoline) at WOT. Then retest your mixture with the secondaries connected and see what it remains the same or leans out.
@@SummitRacing thanks for the reply, this is great advice. I do have an AF gauge so this will make it easy. So what I’m understanding is that it’s not normal to be nearly squared? What if the primary is good and it still wants squared? I will try adjusting floats slightly as well. Thanks again!!!
great video and clear instruction, in the second method the vacuum reading - 2 and the result devided in 2 is the correct way ??? for example if the vacuum reading is 13 , correct power valve size is 5.5 ?
Hi rezajahanshahi, As a general rule of thumb, to achieve the proper power valve starting point, a vacuum gauge is placed on a manifold vacuum port. This should be done at operating temperature with the ignition timing set already! Manifold vacuum divided by 2 with .5 added for your result. The actual equation will look something like this…. 14 / 2 = 7 + .5 = 7.5 If the car being tested has an automatic trans. then the test should be done while in gear (under load). If it is a manual shift trans. then the test is done in neutral with no load. The key is trying to simulate how the car will be driven and expected to react from a stop. You’ll see that emphasis is put on starting point above. You may/will need to change this power valve size according to your driving preferences by .5 - 1.5 There are many power valve sizes available to suit your needs. Give us a call if we can assist in any way! 1-330-630-0240.
Yes, divide by half. If you go to a real radical cam you may want to play around with different numbers or even buy a power valve plug to block of your secondaary power valve.
I have a Ford f 150 truck 89 model was factory efi now holley carb diet it's a 5ltr winsor gt40 heads weiland intake 600 holley running 65 main jets if I put 63 will it improve fuel economy
nathan schmidt Yes, check the color of your spark plugs to see if you can go leaner. You can also buy a Air/fuel mixture gueage assy that will tell you if you can go leaner/richer.
Recently my engine has been running really poorly at cold idle (sputtering, missing, rough, stalls at stops if I don't keep my foot on the brake and gas) I've replaced the spark plugs, spark plug wires, ignition cylinder, distributor, cap and rotor, so it is the carb is giving me grief, it's a Holley 4160 600 cfm four barrel. I've adjusted the choke to various stages, I have the fuel idle screws adjusted to the best vacuum at 1 turn out and I've even taken the carb apart and cleaned it out, yet it still has a crappy idle when cold. I just can't figure it out, could jetting be a problem? it ran fine since I got the carb in September, until recently in mid December
Hi dethmetel, Due to colder, more dense air in the winter months; it is certainly not uncommon to have to increase jet size slightly to maintain a good mixture in the cylinders.
I bought a new 600 cfm dubpumper brawler by Holley , my truck is stumbling thruout the start and curve , I realize it's not able to supply the 355 with aluminum heads with enuff gas , so I'm needing to see if anyone knows what size jets come already installed in that carb?
Norm, I just bought a carb spacer for my Holley to help stop gas peculation, my question is do I have to make any adjustments or upgrades or will it run the same?
Ron General rule of thumb is : The longer the intake runner, the richer the jets you will need. I would be surprised if a 1" intake increase would be more than a jet 1 # higher though.
Are you afraid to say the word vacuum? Everything is high or low pressure but nothing about the V word. You did talk about a Vacuum gauge. But not in relation to how that effects pressure.
IVE BEEN MESSING WITH HOLLEYS FOR YEARS, READ ALOT OF STUFF ON THEM TOO, BUT MY MAN, YOU TOOK IT TO ANOTHER LEVEL, VERY UNDERSTANDABLE FOR THIS OLE COUNTRY BOY, THANKS ALOT, YOU ARE GREAT AT TEACHING AND VERY KNOWLEDGEABLE.
With just the most basic knowledge, I watched this video to understand how my carburetor works. Mission accomplished! Great video.
+Dave Turbovsky,
Thank you for watching, Dave!
Thank you Norm and the Summit Racing team for taking the time to make these videos. They are more help than you will ever know! Great job and keep em coming!
Thanks for the great videos. I have learned more about carburetors watching your videos .I think you are a good teacher with a sense of humor to boot. Thanks.
Greetings sako1952,
Humor is good - never take yourself too seriously. The more you know about something the more liberal you should be about sharing that knowledge. Thank you for the kind words.
-Norm
i know it is kind of off topic but do anyone know of a good site to stream newly released series online ?
With rare exception… if, in your original tuning you were able to dial in your idle circuit correctly then changing the jets and or working on the main circuit should not constitute the need for an additional idle mixture screw adjustment.
Excellent video, been watching countless videos that didnt help... this video got me back on the right track
Thank you for watching!
made this so easy to understand, I was surprised. thank you great video! ive been having carb question about tuning, but I now have a level of understanding
The videos was very helpful for understanding things. But I believe you misspoke when talking about the Venturi. You go from hight pressure low VELOCITY (not volume), to a low pressure high velocity, and back again. I believe this is what it is supposed to be
Thank you, Thomas. We really appreciate your kind words. Please let us know if you have any additional questions! We have two more Holley carb videos coming soon so stay tuned :)
Thanks for the video. I like using Wideband O2 to help out too.
Thanks for watching, Dusttin!
Good Explanation Norm.
i appriciate your effort on this complex topic.
iv'e made my decision, i'm Running for a Fuel injection Retro Kit!..
Thank you for watching!! :)
It may be helpful to understand total pressure and its components static and dynamic pressure. Total pressure equals static pressure + dynamic pressure. Dynamic pressure is a function of velocity. Specifically velocity squared. When the video presents HiV and LOV it is velocity. Since total pressure is a function of both static and dynamic pressure, when velocity increases because cross sectional area decreases in the venturi (when flow is unchoked), the dynamic pressure is increasing causing a decrease in static pressure because total pressure is constant. If a circuit has one end attached to the high dynamic (high velocity) pressure and the other to low dynamic pressure (atmospheric pressure), there will be flow high to low.
That is what I needed to know. Thank you
Norm, is a awesome carb professor!!!!
He really is great! Thank you!
edelbrock carb 1406 used on 454 it bogs put same carb on crate 350 it still bogs down black smoke out tail pipe both engines
Ron,
Going for a drive while watching a vacuum gauge sounds like tuning the power circuit (Power Valve). Generally I would use a vacuum gauge for tuning the idle circuit, the power circuit and possibly as an aid in tuning the secondary side of a vacuum secondary carburetor. Ideally you would want to know the vacuum that the engine is producing at idle, at or near a mid-range steady-state cruise, and at W.O.T. and make your adjustments from these findings. Do you have any specifics? Let me know.
Do u guys have a video on air bleeds??
All your videos kick ass norm!!!
this guy is awesome. so informational. its very helpful how he breaks it down and explains it all piece by piece. but i have a quick question after changing the main jets do you have to go back and re-adjust the idle air screws?
I know this thread is old but this is the same question I have
Generally no, the idle circuit is independent of the jets.
I have 62 cc/minute front and rear max vaccum at idel. I can let out the clutch and move the truck around. I need to find a 600cfm choke or send it to Summit for repair. Or get the Atomic system.
Norm, when you're talking about jet tuning using a vacuum gauge inside the car how fast are you supposed to be going... (MPH)
I have a 427 S/B 520HP with a 850 quick fuel carb. The youtube vids iv seen tell me to set mixture screws to start at 1an a half to 1an quarter turns an turn out to fine tune. My best vac occurs at less than 1 turn out am i missing something any help please
hi ron i have a 1150 holley dom, i can,t get the .015 on my carb, i tryed every way but not having any luck, can you help me. jimmy
sorry its on the pump, on both
Hi! Thank you for the question. Our tech department asked if you could give us a call at 1-330-630-0240. We look forward to your call. Thanks for watching!
Im looking at tuning my mains in a 1050 dominator. Im getting this is a street car you are tuning for? I cant exactly cruise down the road in my race car. How would i find the starting point on the primaries since it is pretty much wide open when I run it? Thanks for any help.
Thanks for the video!! Why does my setup like squared jets, meaning nearly the same all around. There’s a power valve in the primary but none in the secondary. 4150 650 DP. Thanks!
On average, a power valve makes up for approximately 5-7 jet sizes. There are a couple of reasons why your set up could be a little different. Float level, emulsion sizes in the metering block, high-speed air bleed differences to name a few. You may be a little rich on the primary side, and a leaner secondary side balances it out under WOT. If you suspect this, try disconnecting the secondary linkage and tune the primary side mixture for 12.5 -13.0 (assuming your running gasoline) at WOT. Then retest your mixture with the secondaries connected and see what it remains the same or leans out.
@@SummitRacing thanks for the reply, this is great advice. I do have an AF gauge so this will make it easy. So what I’m understanding is that it’s not normal to be nearly squared? What if the primary is good and it still wants squared? I will try adjusting floats slightly as well. Thanks again!!!
Everything!
thank you thank you thank you
Was Norm a high school science teacher?
great video and clear instruction,
in the second method the vacuum reading - 2 and the result devided in 2 is the correct way ???
for example if the vacuum reading is 13 , correct power valve size is 5.5 ?
Hi rezajahanshahi,
As a general rule of thumb, to achieve the proper power valve starting point, a vacuum gauge is placed on a manifold vacuum port. This should be done at operating temperature with the ignition timing set already! Manifold vacuum divided by 2 with .5 added for your result. The actual equation will look something like this…. 14 / 2 = 7 + .5 = 7.5
If the car being tested has an automatic trans. then the test should be done while in gear (under load). If it is a manual shift trans. then the test is done in neutral with no load. The key is trying to simulate how the car will be driven and expected to react from a stop.
You’ll see that emphasis is put on starting point above. You may/will need to change this power valve size according to your driving preferences by .5 - 1.5
There are many power valve sizes available to suit your needs. Give us a call if we can assist in any way! 1-330-630-0240.
Yes, divide by half. If you go to a real radical cam you may want to play around with different numbers or even buy a power valve plug to block of your secondaary power valve.
Best invention for tuning carbs is an AFR gauge.
I have a Ford f 150 truck 89 model was factory efi now holley carb diet it's a 5ltr winsor gt40 heads weiland intake 600 holley running 65 main jets if I put 63 will it improve fuel economy
nathan schmidt Yes, check the color of your spark plugs to see if you can go leaner. You can also buy a Air/fuel mixture gueage assy that will tell you if you can go leaner/richer.
I wanted to say thanks Norm for
I have a 1250 dominator and have 99 jets all the way around. Now what do I do?
Hi J1978watt,
We need some additional information from you. Can you please give our tech line a call? 1-330-630-0240. Thanks!
Recently my engine has been running really poorly at cold idle (sputtering, missing, rough, stalls at stops if I don't keep my foot on the brake and gas)
I've replaced the spark plugs, spark plug wires, ignition cylinder, distributor, cap and rotor, so it is the carb is giving me grief, it's a Holley 4160 600 cfm four barrel. I've adjusted the choke to various stages, I have the fuel idle screws adjusted to the best vacuum at 1 turn out and I've even taken the carb apart and cleaned it out, yet it still has a crappy idle when cold.
I just can't figure it out, could jetting be a problem? it ran fine since I got the carb in September, until recently in mid December
Hi dethmetel,
Due to colder, more dense air in the winter months; it is certainly not uncommon to have to increase jet size slightly to maintain a good mixture in the cylinders.
Summit Racing It's like it's getting too much gas though. I recently replaced the power valve and it helped it bit.
I'm only running 68 jets
cool!
I bought a new 600 cfm dubpumper brawler by Holley , my truck is stumbling thruout the start and curve , I realize it's not able to supply the 355 with aluminum heads with enuff gas , so I'm needing to see if anyone knows what size jets come already installed in that carb?
Hi, Primary is 66 secondary is 72
Thanks there ,but the next up would bewhat? Like a 68 & 74?
68 and 74 are correct. Most people increase or decrease the jets sizes by 2 when making adjustments.
It's six foot, seven foot, eight foot bunch, daylight come and I wanna go home.
Norm, I just bought a carb spacer for my Holley to help stop gas peculation, my question is do I have to make any adjustments or upgrades or will it run the same?
Ron General rule of thumb is : The longer the intake runner, the richer the jets you will need. I would be surprised if a 1" intake increase would be more than a jet 1 # higher though.
Seria bueno que sean completamente en español
Are you afraid to say the word vacuum? Everything is high or low pressure but nothing about the V word. You did talk about a Vacuum gauge. But not in relation to how that effects pressure.
11:59.... fed up of explaining? Feel you are having to dumb it down?
Your continual use of OK is condescending.
Worst, most comical explanation of how a Venturi works that I've ever heard in my live. Everyone listening just got dumber for having listened to it.