Holley 4777 stumble--fiddling and fixed!

[1980RS]

Thanks for your response. They’re the same carburetor. I’ve been in the carburetor business since high school when I was an apprentice in the mid 90’s. I like to hear what people think and which old carburetor myths are still out there. The 3/8’s float adjustment along with other tuning information is in the tuning literature with every Edelbrock carburetor. It’s not a secret, there’s a 26 page PDF on Edelbrock’s website that would have saved you two weeks. As for the jetting, it all depends on weather the carburetor was manufactured before or after ethanol was added to the fuel. Pre-ethanol carburetors use smaller jets because the fuel had more hydrocarbons. The 600 cfm carburetor seemed slower because of the loss of velocity compared to the 500 cfm carburetor. A 500 cfm carburetor is plenty for a 6,000 rpm 350 street engine. Inadequate air filters are usually the flow restrictions at higher RPM’s. A properly modified and tuned Quadrajet will always be the best choice on a street strip car. Unless you absolutely want a square bore carburetor. Then use a motorcraft 4100. The annular discharge boosters work very well. That’s why Ford wouldn’t sell the patent to Holley until carburetors were obsolete on production cars. I hope this helps and saves you time in the future.

You are right about the 4100 series Ford carb. I think Holley sold those in the 90's and now Summit makes use of that design. The only downfall the 4010 carb had was when the top plate warped.

 

[pooch400]

You are right about the 4100 series Ford carb. I think Holley sold those in the 90's and now Summit makes use of that design. The only downfall the 4010 carb had was when the top plate warped.

I’ve seen a lot of warped top plates on those during rebuilds. The problem isn’t the design, it’s people over tighten the screws. Instead of replacing the gasket people crank down on the screws or they think the screws are too loose because they still turn when they’re new. Most issues with carburetors are mechanic error from inexperience. The same thing happens to Holley accelerator pump covers. I filed hundreds of those as an apprentice.

 

[1980RS]

I’ve seen a lot of warped top plates on those during rebuilds. The problem isn’t the design, it’s people over tighten the screws. Instead of replacing the gasket people crank down on the screws or they think the screws are too loose because they still turn when they’re new. Most issues with carburetors are mechanic error from inexperience. The same thing happens to Holley accelerator pump covers. I filed hundreds of those as an apprentice.

Now that you bring that up about the accelerator pump covers I have a fix for that. I have a thing called a Worksharp electric grinding wheel and when you plop the cover on the sanding disc it makes them perfectly flat again for a no leak pump. for a few years I sold them at swap meets for $5 with an exchange and $20 without. One swap I made $100 and had a lot of work to do the next week.

 

[pooch400]

Now that you bring that up about the accelerator pump covers I have a fix for that. I have a thing called a Worksharp electric grinding wheel and when you plop the cover on the sanding disc it makes them perfectly flat again for a no leak pump. for a few years I sold them at swap meets for $5 with an exchange and $20 without. One swap I made $100 and had a lot of work to do the next week.

That’s a great idea and a lot faster than using a file lol.

 

[Ratty_81]

Put some light springs in my distributor and went to 31/28 on my squirters. Timing at 34 deg, all in by 3k and initial is 14. Still starts easy. Stumble is 95% gone. Might try 28/28 and or different cam profiles to clean it up more. Being a stick car, I can live with it the way it is, though.
Thanks everyone!

 

[1980RS]

Put some light springs in my distributor and went to 31/28 on my squirters. Timing at 34 deg, all in by 3k and initial is 14. Still starts easy. Stumble is 95% gone. Might try 28/28 and or different cam profiles to clean it up more. Being a stick car, I can live with it the way it is, though.
Thanks everyone!

Put a couple of Thompson power plates under those squirters it will fix any stumble. I got 2 of them on a 750 QF carb and that's why I bought the QF. pulled off the plates and sold the carb for a $50 profit the next day. Put the little brass plates on my 650 DP and BAM no more hesitation, mine were free but they cost $40 each. Kind of spendy but what's you time worth these days.

 

[Ratty_81]

Thanks @1980RS , I’ll look into them.

 

[G72Zed]

The first original 4777 came with 25 shooters, after that, all iterations came with 28-28 shooters.

I always say "Time up, shooter down".

Car cleans up, throttle response gets crispy and accelerates better with less fuel washing, especially on manuals.

 

[76z28]

The first original 4777 came with 25 shooters, after that, all iterations came with 28-28 shooters.

I always say "Time up, shooter down".

Car cleans up, throttle response gets crispy and accelerates better with less fuel washing, especially on manuals.

I left my shooter at 33 and boy after installing headers this thing is running pretty darn well. I do think I have an issue with valve seals(WOT it seems to be burning oil but nothing outside of that). I have a set of l98/zz4 heads out in the shed I might have built to throw on. Nice bump in compression and I will finally see if it is a 4.0 or 3.875 bore!