Why the Carter AFB? Arguably one of the worst carbs vs the Holly, vs early 80's variable ventouri on Fords that was complete trash? Carter owners could change to a Holly and get instant HP.
Why the Carter AFB? Arguably one of the worst carbs vs the Holly, vs early 80's variable ventouri on Fords that was complete trash? Carter owners could change to a Holly and get instant HP.
I'm guessin' that could start a lot of arguments.
My fav 4bbls were Carter AFBs. Dirt simple and would always kit well.
Holleys worked great when new, but one hiccup/backfire would blow out the power valve (and often invert the choke). Also, since there were about a gazillion models of each size, kits were always iffy at best. Not to mention the fiber floats would get fuel-soaked and change the float level, so after they dried out while you were installing the kit, you had to reset the level after they got wet again.
Sorry, just not a big Holley fan.
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You guys asked for it now.. have a seat this will be a while.
I liked the Variable Venturi that Ford installed on that 351W. It actually worked very well as long as you knew what to do to it.
I also like Holley and Q jets I have about 20 carbs worth running all kinds of them in fact I have actually tested my highly Modified 750 #4779 against my tuned Q jet there was less than 10HP between them and that is due to 1 point different AFR readings.
I have ran multiple back to back test using the 3 popular carbs the Holley The AFB style and the Qjet and when tuned correctly you do not notice you even swapped carbs.
Now Stock VS stock VS stock with only jet changes the Holley 4779 double pumper and 3310 vacuum secondary with straight leg boosters both holleys were always way down on upper rpm power vs a 750 Q jet that has had the secondary air door set to open fully. and the Holleys were also way down on upper rpm power vs the 750 AFB with only jet changes.
This was a 7000+ rpm 350 that the carbs were tested on for max performance.
Not being one to give up on any carb I began tweaking the Holleys.
Starting with modifying the airhorn Choke tower.
Then centering and polishing the boosters as most were off center. Then polishing and slightly enlarging the venturies.
Finally thinning the throttle shafts and installing smaller head throttle blade screws.
Now the 750 cfm could be realized.. If you research actual flow on the Holley750's they do not even break 700 most of the time.
Mixture distribution has much more to do with power sometimes than what a carb will flow.
Anyway I did finally with those mods get the 4779 and 3310 to pull hard upstairs.
I have a very tweaked 4779 right now that on a square bore intake it makes about 3HP more average through the entire curve than a modded Qjet. But install the Holley onto a spreadbore intake and then the tables got flipped.
I did not test with a 1" spacer which could cure some of the mixture distribution issues.
Lots of dyno testing.
Now the deal with What you noticed Dennis with the AFB vs Holley could stem from the old days when the AFB's you mostly found were smaller than 750.
I have many of the small AFB carbs .. say 470cfm and some 625 and some 600 edelbrock performer carbs.
Those small ones really nose over on the big end.
The 600 will begin to flatten out about 6000 and you can tell it is way down on power at about 5000 rpm compared to the larger carbs. This is on a weak ass 350 of mine that makes max HP at 5700.. but will twist to 7000.
It is even more noticeable on the larger cammed stuff.
But Why the 750 AFB because I can tune it much quicker than the Holley for getting a baseline to break in this engine.
I am sure my 4779 and a Q jet will see service on this engine before it is all said and done.
Someone here can attest to how well this 750 AFB runs. I loaned it to him to run on his 57 chevy 2 door that beat my 57 chevy 4 door in the ultimate slow car battle. His 2 door 4 speed aluminum head with headers and lumpy cam + loud exhaust. Vs my stock cast iron intake and Qjet 268H cam with iron exhaust manifolds and TH350+ quiet exhaust.
They said it was the best running driving carburetor they ever had.
I liked the Variable Venturi that Ford installed on that 351W. It actually worked very well as long as you knew what to do to it.
I also like Holley and Q jets I have about 20 carbs worth running all kinds of them in fact I have actually tested my highly Modified 750 #4779 against my tuned Q jet there was less than 10HP between them and that is due to 1 point different AFR readings.
I have ran multiple back to back test using the 3 popular carbs the Holley The AFB style and the Qjet and when tuned correctly you do not notice you even swapped carbs.
Now Stock VS stock VS stock with only jet changes the Holley 4779 double pumper and 3310 vacuum secondary with straight leg boosters both holleys were always way down on upper rpm power vs a 750 Q jet that has had the secondary air door set to open fully. and the Holleys were also way down on upper rpm power vs the 750 AFB with only jet changes.
This was a 7000+ rpm 350 that the carbs were tested on for max performance.
Not being one to give up on any carb I began tweaking the Holleys.
Starting with modifying the airhorn Choke tower.
Then centering and polishing the boosters as most were off center. Then polishing and slightly enlarging the venturies.
Finally thinning the throttle shafts and installing smaller head throttle blade screws.
Now the 750 cfm could be realized.. If you research actual flow on the Holley750's they do not even break 700 most of the time.
Mixture distribution has much more to do with power sometimes than what a carb will flow.
Anyway I did finally with those mods get the 4779 and 3310 to pull hard upstairs.
I have a very tweaked 4779 right now that on a square bore intake it makes about 3HP more average through the entire curve than a modded Qjet. But install the Holley onto a spreadbore intake and then the tables got flipped.
I did not test with a 1" spacer which could cure some of the mixture distribution issues.
Lots of dyno testing.
Now the deal with What you noticed Dennis with the AFB vs Holley could stem from the old days when the AFB's you mostly found were smaller than 750.
I have many of the small AFB carbs .. say 470cfm and some 625 and some 600 edelbrock performer carbs.
Those small ones really nose over on the big end.
The 600 will begin to flatten out about 6000 and you can tell it is way down on power at about 5000 rpm compared to the larger carbs. This is on a weak ass 350 of mine that makes max HP at 5700.. but will twist to 7000.
It is even more noticeable on the larger cammed stuff.
But Why the 750 AFB because I can tune it much quicker than the Holley for getting a baseline to break in this engine.
I am sure my 4779 and a Q jet will see service on this engine before it is all said and done.
Someone here can attest to how well this 750 AFB runs. I loaned it to him to run on his 57 chevy 2 door that beat my 57 chevy 4 door in the ultimate slow car battle. His 2 door 4 speed aluminum head with headers and lumpy cam + loud exhaust. Vs my stock cast iron intake and Qjet 268H cam with iron exhaust manifolds and TH350+ quiet exhaust.
They said it was the best running driving carburetor they ever had.
After reading all that, I just have this to say. I hate Holly carbs.
I am with you to a point.
Stock they never measured up.
Buddy had a 3310 As we know that is a 750 vacuum secondary ..he had the percys blocks that allows you to make jet changes by turning a screw on the outside.
Anyway he was Holley all the way..He always asked why I run the AFB and Q jet. I said they pull harder on the top end.
He called BS.
I let him install and tune his Holley on my car.
We drove it before and after.
He did not ever say his Holley was better after that..In fact he ended up running a Qjet I tweaked for him and later went AFB.
Now The Holley jet changes sucked from stock,, with their cork gaskets that always stuck even chapstick on them did not help 100%.
Fast forward to today... they have Blue NON stick gaskets that are awesome.
Problem is the Holley has a raised bead where the gasket seals.. that bead is for making the cork gasket stay in place.. no way to shrink or get out of place with a bead lock.
Now with the Blue non stick you need to remove that bead as it will eat through the nonstick and some of the gasket will stick.
Not always as some have a shallow bead from being rebuilt so many times and others will have a very pronounced bead.. it is not needed with the new blue gaskets as they do not have the shrink issues like the old cork.
That makes jet and other changes much easier.
I will say i like the old Holleys much better than many of the new ones like street avenger series and some of the knock off's.
Those things suck.. in a bad way.
Anyhoo I got the porting and some of the welding finished on that cast iron Qjet intake.
All my carbide cutters are dull..
I actually used my 225 ac lincoln to gouge out the plenum area..
First time to try that.. what a time saver.
Yes I thought of doing that all by myself.
Corndogs are here 50 cents today at sonic.
Stock they never measured up.
Buddy had a 3310 As we know that is a 750 vacuum secondary ..he had the percys blocks that allows you to make jet changes by turning a screw on the outside.
Anyway he was Holley all the way..He always asked why I run the AFB and Q jet. I said they pull harder on the top end.
He called BS.
I let him install and tune his Holley on my car.
We drove it before and after.
He did not ever say his Holley was better after that..In fact he ended up running a Qjet I tweaked for him and later went AFB.
Now The Holley jet changes sucked from stock,, with their cork gaskets that always stuck even chapstick on them did not help 100%.
Fast forward to today... they have Blue NON stick gaskets that are awesome.
Problem is the Holley has a raised bead where the gasket seals.. that bead is for making the cork gasket stay in place.. no way to shrink or get out of place with a bead lock.
Now with the Blue non stick you need to remove that bead as it will eat through the nonstick and some of the gasket will stick.
Not always as some have a shallow bead from being rebuilt so many times and others will have a very pronounced bead.. it is not needed with the new blue gaskets as they do not have the shrink issues like the old cork.
That makes jet and other changes much easier.
I will say i like the old Holleys much better than many of the new ones like street avenger series and some of the knock off's.
Those things suck.. in a bad way.
Anyhoo I got the porting and some of the welding finished on that cast iron Qjet intake.
All my carbide cutters are dull..
I actually used my 225 ac lincoln to gouge out the plenum area..
First time to try that.. what a time saver.
Yes I thought of doing that all by myself.
Corndogs are here 50 cents today at sonic.
You had me at corndog.
Guess I was from an earlier day. Had brass floats in mine.I'm guessin' that could start a lot of arguments.
My fav 4bbls were Carter AFBs. Dirt simple and would always kit well.
Holleys worked great when new, but one hiccup/backfire would blow out the power valve (and often invert the choke). Also, since there were about a gazillion models of each size, kits were always iffy at best. Not to mention the fiber floats would get fuel-soaked and change the float level, so after they dried out while you were installing the kit, you had to reset the level after they got wet again.
Sorry, just not a big Holley fan.
Maybe so. Most of my Holley experience was around '78 to '81.
Mine in the 60's. Didn't have the power valves, etc. Those came later.
Hehe... I was 12 when the '60s ended.
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