Hello Randy, another great video. I thought I would mention, we called the umbrella type inlet check valve is an elastomer valve. Keep up the good work!
Been watching your videos lately great info. I worked on a lot of holleys in the mid late 90’s and haven’t really touched them since. I have a Holley truck avenger 670 known for a lean spot between the transition and primary boosters. It’s on a sbc 357 11.12:1 compression vortec heads and a comp cams xtreme 4x4 cam close to .500 lift but I’m at 10k feet above sea level and it’s on an 85 gmc k2500 with a sm465 4 speed manual. I’ve tuned the eccelerator pump up and down timing main jets on the primary side. Transfer slots are good idle screws work properly. My afr readings are rich everywhere but the lean spot. I opened up my ifr’s from .027 to .029 and my transition went from roughly 12.5 to 11 on transition. Idol air bleeds are stock at .063. There’s no high speed air bleeds. I’ve tried everything except excessive drilling and tapping. Best vacuum is at 10 at idol at my altitude. It will lean out and stay there till I let off the throttle only in second and third gear. First rips. I don’t really want to abandon this carb like so many have. Seems like I’m not getting enough vacuum to make the transition any ideas? Thank you!
When you hit your lean spot can you aceelerate more and drive through it. One other thing you say its worse in 2nd and 3rd gear, does it happen in 4th gear, also send me your list # off your carb and i'll take a shot at it, there is so things that can cause these types of problems. Also what rpm is the lean spot.
Thank you for responding. The list number is 90670. It’s a 4 speed with low 1st 2nd and 3rd it happens every time in second and third And in first if the load is high and never in low gear. I can’t drive through it at all it leans out for as long as I hold the throttle in that position. there has been times I pumped the pedal in hopes that the accelerator pump would help but no change. Rpm is 1000-1500 in 2nd a little higher maybe up to 1700 in 3rd once past the lean spot she’s great. I have tried power valves from 2.5 through 6.5 and seems a bit better on the 6.5 and have a 7.5 and an 8.5 coming to try. Thank you !
There's alot to look at , this could be a carburetor problem or fuel supply issue, or carb not venting properly . I believe i would start at fuel supply first, with the ignition disabled remove fuel line and check fuel delivery electric or manual fuel pump should have a solid stream around 3 inches long and manual pulsing 3inches. Check your carb for venting restricting , drain the fuel bowl and check for water. Also defective ignition coil can cause this. If i had a spare carb or one you could borrow i would try that first. I've seen so many crazy things an engine back fire and damage the carb float and it hang up restricting the fuel to the bowl. And there is always a chance of trash in the main well floating around between the jet and the booster with no way to escape. I know this is a lot to do if it was me i would check fuel flow first if ok then i woul try and substitute a carb that way you will know which way to go from there. Hope this helps.
@@holleycarbshowtosadvice40y90thank you again for responding. Fuel supply and ignition are all new and functioning properly. It will rev and pull under load at 6-7k rpm all day long once past the lean spot. It runs fine with the quadrajet on it but I live off road in the mountains and this truck spends 90% of the time on very uneven terrain. That’s why I wanted to try this truck avenger carb. The vents are clear I did verify that yesterday. When I drilled and tapped the idle Fuel restrictions which helped air fuel ratio. I have everything dialed in to 12.5-13.5 on my afr guage. But the lean spot. I noticed what seams to be check valves or balls in the main wells. They clunk when I flip the block upside down and can see them flopping around. Are these normally in Holley metering blocks? If not I wonder if that’s one way they keep the carb from flooding on steep inclines. And could that be causing the problem. Thank you again for your time.
Lets go Randy! Great video as always. I'm passing on the knowledge to a couple young bloods to get their rigs down the road. Always pay it forward. Thanks for the knowledge 🍻🍻
Glad to see a new video out Randy and Mr' Cameraman. I just picked up a new to me 850 CFM Holley 4781. Was planning on using AED 6580 metering blocks. Do I need two, or just one for the Primary side?
AED makes great products, this comes down to personal preference how far you won't to modify it, I believe you could make good either way. I do believe the primaries are most important. Hope this helps.
Excellent vid once again. Have you got a vid on pump cam selection? I generally start with the red cam but sometimes when changing them its hard to tell the difference what with so many other things happening at once
I'm on my daughter's TH-cam. I inherited my dad's car. (My daughter's grandfather's car.) I never messed with Holley carbs because of the horror stories I've heard when I was a teenager. So I just stuck to the Quadrajet carbs. Now I'm 58 and learning how Holley carbs work. My first tackle with my dad's car was the accelerator pump not working correctly or not at all. I removed the carb and removed the accelerator pump cover. It has the check ball design. Anyway, the check ball was off to the side a bit and I'm guessing that the check ball wouldn't always get pushed up to the hole to seal it so the gas could be pumped to the squirter nozzles. So I put check ball over/into the hole and I pressed the metal strip that keeps the check ball from falling out towards the check ball itself. I'm guessing that there's about a .010" gap between the check ball and the metal strip. The only downside that I can see by doing this is that the car has a four speed transmission and if you're doing a lot of quick shifts the fuel might be restricted somewhat to keep the accelerator pump housing full. I don't plan on racing it so I don't care. Just by doing that the car started perfectly. I do have a slight stumble if the car is idling in gear and I goose the throttle. I'm betting it's because I adjusted the accelerator pump wrong. I misunderstood and have a .010" gap at idle, not WOT. 😅 But from what I see on the internet, I'm going to adust the accelerator pump at .015" at WOT instead of .010" just to be on the safe side. I'm glad that I checked your video out because you explained the check valve under the squirter and its purpose. If I still have the stumble that'll be the next thing I check. It's good to see people like you sharing your knowledge. I do appreciate it.
Make sure you have no clearence in the accel. pump arm at idle, but at wide open throttle .015 is fine. Sometimes you have to switch to a less agressive accel. pump cam in order to get your clearences correct at wot. If your still having a hesitation go up .003 on your accel. pump discharge nozzles. Always make sure timing is set properly and advancing as your rpms increase. Hope this helps
Great video, thank you. I have the opposite issue... an unexpected acceleration just as I'm pushing down on the accelerator... and with 640 ft/lb torque, it's kinda neck snapping.... any thoughts?
measuring the clearance on that pump check was something else. i confirmed it sealing by filling it up with fuel and ensuring zero bypass ..on the discharge check too
Randy, I have a Holley 750 vacuum secondary with an HP body, 82750SA. The carb runs great. However, I get an initial AFR lean spike and quick bog at the onset of the secondaries opening. Once they open, the car hauls. It came with the plain spring. Going to a stiffer spring makes the bog worse an last longer. Going to a lighter spring doesn’t help. Idle, transition, accelerator circuit, primary circuit, and WOT are perfect. Any ideas?
Things that can cause these symtoms, secondary coming in to fast or jetting to lean, float level to low . Check your primary pump cam, see if its a pink cam the pink cam carries a longer duration pump shot may help.
I would start with making sure your float level is where it should be and then upping the secondary jetting a bit since there is no secondary accel pump nozzle. Pending on how far open the primary blades are and what your idle is set at.... you could possibly afford to close your primary blades a touch and then open your secondary blades a touch to get more into the secondary transfer slots.
Most of the carbs that have ball checks in the pump circuit have some sort of counter weight or there was some that were spring loaded like the quadrajet I'll try to do a video on different carbs to show how there check system works.hope this helps.
@@holleycarbshowtosadvice40y90 excellent. And thanks for your efforts, carb tuning is becoming a lost art. Would be nice to see something on the 4180C Ford customization, if you have one laying around. Holley completely washes their hands of those and of course autocraft is no longer around.
A little constructive criticism. You don’t show how to adjust it so you’ve just unincluded half your audience. Also since so many make this mistake you must ALWAYS make sure that the lighting and angle are good so that people can see exactly what you are doing.
We do the best we can, and try to improve. If you have a problem you can always leave me a message. Other than that if your not happy there's always other channels out there. Hope this helps
Good stuff Randy, thank you!
Thanks
Hello Randy, another great video. I thought I would mention, we called the umbrella type inlet check valve is an elastomer valve. Keep up the good work!
Absolutely.
Been watching your videos lately great info. I worked on a lot of holleys in the mid late 90’s and haven’t really touched them since. I have a Holley truck avenger 670 known for a lean spot between the transition and primary boosters. It’s on a sbc 357 11.12:1 compression vortec heads and a comp cams xtreme 4x4 cam close to .500 lift but I’m at 10k feet above sea level and it’s on an 85 gmc k2500 with a sm465 4 speed manual. I’ve tuned the eccelerator pump up and down timing main jets on the primary side. Transfer slots are good idle screws work properly. My afr readings are rich everywhere but the lean spot. I opened up my ifr’s from .027 to .029 and my transition went from roughly 12.5 to 11 on transition. Idol air bleeds are stock at .063. There’s no high speed air bleeds. I’ve tried everything except excessive drilling and tapping. Best vacuum is at 10 at idol at my altitude. It will lean out and stay there till I let off the throttle only in second and third gear. First rips. I don’t really want to abandon this carb like so many have. Seems like I’m not getting enough vacuum to make the transition any ideas? Thank you!
When you hit your lean spot can you aceelerate more and drive through it. One other thing you say its worse in 2nd and 3rd gear, does it happen in 4th gear, also send me your list # off your carb and i'll take a shot at it, there is so things that can cause these types of problems. Also what rpm is the lean spot.
Thank you for responding. The list number is 90670. It’s a 4 speed with low 1st 2nd and 3rd it happens every time in second and third And in first if the load is high and never in low gear. I can’t drive through it at all it leans out for as long as I hold the throttle in that position. there has been times I pumped the pedal in hopes that the accelerator pump would help but no change. Rpm is 1000-1500 in 2nd a little higher maybe up to 1700 in 3rd once past the lean spot she’s great. I have tried power valves from 2.5 through 6.5 and seems a bit better on the 6.5 and have a 7.5 and an 8.5 coming to try. Thank you !
There's alot to look at , this could be a carburetor problem or fuel supply issue, or carb not venting properly . I believe i would start at fuel supply first, with the ignition disabled remove fuel line and check fuel delivery electric or manual fuel pump should have a solid stream around 3 inches long and manual pulsing 3inches. Check your carb for venting restricting , drain the fuel bowl and check for water. Also defective ignition coil can cause this. If i had a spare carb or one you could borrow i would try that first. I've seen so many crazy things an engine back fire and damage the carb float and it hang up restricting the fuel to the bowl. And there is always a chance of trash in the main well floating around between the jet and the booster with no way to escape. I know this is a lot to do if it was me i would check fuel flow first if ok then i woul try and substitute a carb that way you will know which way to go from there. Hope this helps.
@@holleycarbshowtosadvice40y90thank you again for responding. Fuel supply and ignition are all new and functioning properly. It will rev and pull under load at 6-7k rpm all day long once past the lean spot. It runs fine with the quadrajet on it but I live off road in the mountains and this truck spends 90% of the time on very uneven terrain. That’s why I wanted to try this truck avenger carb. The vents are clear I did verify that yesterday. When I drilled and tapped the idle
Fuel restrictions which helped air fuel ratio. I have everything dialed in to 12.5-13.5 on my afr guage. But the lean spot. I noticed what seams to be check valves or balls in the main wells. They clunk when I flip the block upside down and can see them flopping around. Are these normally in Holley metering blocks? If not I wonder if that’s one way they keep the carb from flooding on steep inclines. And could that be causing the problem. Thank you again for your time.
Thank you for the videos.
Glad to help.
Lets go Randy! Great video as always. I'm passing on the knowledge to a couple young bloods to get their rigs down the road. Always pay it forward. Thanks for the knowledge 🍻🍻
Thanks Ssxon I appreciate it. Take care brother
Acc. Pump adjustment should be .015”-.018” at WOT to avoid damage to the pump diaphragm. 👍
Thanks for watching
@@holleycarbshowtosadvice40y90 Accelerator pump adjustment shared years ago on the PY forums by Tom Vaught long time Holley Engineer. 👍
great info
Thanks .
Glad to see a new video out Randy and Mr' Cameraman.
I just picked up a new to me 850 CFM Holley 4781. Was planning on using AED 6580 metering blocks. Do I need two, or just one for the Primary side?
AED makes great products, this comes down to personal preference how far you won't to modify it, I believe you could make good either way. I do believe the primaries are most important. Hope this helps.
Great video!
Thank you
Good video
Thanks
Excellent vid once again. Have you got a vid on pump cam selection? I generally start with the red cam but sometimes when changing them its hard to tell the difference what with so many other things happening at once
I know what your saying, aggressiveness and dwell time can get confusing. We'll do a video.
I'm on my daughter's TH-cam. I inherited my dad's car. (My daughter's grandfather's car.) I never messed with Holley carbs because of the horror stories I've heard when I was a teenager. So I just stuck to the Quadrajet carbs. Now I'm 58 and learning how Holley carbs work. My first tackle with my dad's car was the accelerator pump not working correctly or not at all. I removed the carb and removed the accelerator pump cover. It has the check ball design. Anyway, the check ball was off to the side a bit and I'm guessing that the check ball wouldn't always get pushed up to the hole to seal it so the gas could be pumped to the squirter nozzles. So I put check ball over/into the hole and I pressed the metal strip that keeps the check ball from falling out towards the check ball itself. I'm guessing that there's about a .010" gap between the check ball and the metal strip. The only downside that I can see by doing this is that the car has a four speed transmission and if you're doing a lot of quick shifts the fuel might be restricted somewhat to keep the accelerator pump housing full. I don't plan on racing it so I don't care. Just by doing that the car started perfectly. I do have a slight stumble if the car is idling in gear and I goose the throttle. I'm betting it's because I adjusted the accelerator pump wrong. I misunderstood and have a .010" gap at idle, not WOT. 😅 But from what I see on the internet, I'm going to adust the accelerator pump at .015" at WOT instead of .010" just to be on the safe side. I'm glad that I checked your video out because you explained the check valve under the squirter and its purpose. If I still have the stumble that'll be the next thing I check. It's good to see people like you sharing your knowledge. I do appreciate it.
Make sure you have no clearence in the accel. pump arm at idle, but at wide open throttle .015 is fine. Sometimes you have to switch to a less agressive accel. pump cam in order to get your clearences correct at wot. If your still having a hesitation go up .003 on your accel. pump discharge nozzles. Always make sure timing is set properly and advancing as your rpms increase. Hope this helps
@@holleycarbshowtosadvice40y90 Thanks for the advice. I'll be sure to remember it.
The shot from the shooters could also put too much fuel too quickly causing the engine to stall . Great video .
Thanks for watching
Great video, thank you. I have the opposite issue... an unexpected acceleration just as I'm pushing down on the accelerator... and with 640 ft/lb torque, it's kinda neck snapping.... any thoughts?
Just don't mash the gas on that beast. Lol
@@holleycarbshowtosadvice40y90 🤣
@@holleycarbshowtosadvice40y90😮
measuring the clearance on that pump check was something else. i confirmed it sealing by filling it up with fuel and ensuring zero bypass ..on the discharge check too
Jack you are right on point and well thought out. Take care.
thanks
Your welcome
Randy, I have a Holley 750 vacuum secondary with an HP body, 82750SA. The carb runs great. However, I get an initial AFR lean spike and quick bog at the onset of the secondaries opening. Once they open, the car hauls. It came with the plain spring. Going to a stiffer spring makes the bog worse an last longer. Going to a lighter spring doesn’t help. Idle, transition, accelerator circuit, primary circuit, and WOT are perfect. Any ideas?
Things that can cause these symtoms, secondary coming in to fast or jetting to lean, float level to low . Check your primary pump cam, see if its a pink cam the pink cam carries a longer duration pump shot may help.
I would start with making sure your float level is where it should be and then upping the secondary jetting a bit since there is no secondary accel pump nozzle.
Pending on how far open the primary blades are and what your idle is set at.... you could possibly afford to close your primary blades a touch and then open your secondary blades a touch to get more into the secondary transfer slots.
Do the versions with a check ball in the squirters as opposed to a check weight also have a weight, or are they all spring loaded?
Most of the carbs that have ball checks in the pump circuit have some sort of counter weight or there was some that were spring loaded like the quadrajet I'll try to do a video on different carbs to show how there check system works.hope this helps.
@@holleycarbshowtosadvice40y90 excellent. And thanks for your efforts, carb tuning is becoming a lost art. Would be nice to see something on the 4180C Ford customization, if you have one laying around. Holley completely washes their hands of those and of course autocraft is no longer around.
I'll see if i have one , that was a great little carb.
A little constructive criticism. You don’t show how to adjust it so you’ve just unincluded half your audience. Also since so many make this mistake you must ALWAYS make sure that the lighting and angle are good so that people can see exactly what you are doing.
We do the best we can, and try to improve. If you have a problem you can always leave me a message. Other than that if your not happy there's always other channels out there. Hope this helps