Initial carburetor setup

[greatscot3]

Hey all

I recently took the carb (Holley 4150 750 CFM) off my 440 Cuda because it needs to be rebuilt. I bought the carburetor probably 35 years ago and it sat new in box all that time. Lately, it sat with ethanol gas in it and being used from time to time and now the float valves won't seal.
I figure most all of the perishable rubber parts are sketchy at best and rather than just replacing the float valves, it would be smarter to go through the whole thing and start fresh.

As it is right now, it is bone stock out of the box from Holley. It started and ran okay for a while until the float valves started acting up but maybe could be better.

I wondered if anyone here has some idea or suggestions about what they would change as the carbs baseline regarding jetting, power valve, squirter size etc.

As some background information on the engine etc., it's a '68 440 out of a GTX with forged crank and forged pistons at about 9.5-1 with a Comp Cams 230-230 .480" lift with a 110 LS angle.
It's got Edelbrock E street aluminum heads.
Stock HP exhaust manifolds with dual 2.5" pipes with Flowmasters and an X-pipe crossover, a Holley Street Dominator single plane intake and a Tremec 5 spd. and 373 gears in a 489 8 3/4" with sure grip.

Any suggestions on first set up of the rebuilt carb would be much appreciated.

Thanks, Jon S.

 

[Challenger RTA]

Take it apart first and see what it looks like inside. that will determine what you need to do. ethanol gas just tears the older build carbs up.

 

[Chryco Psycho]

I agree with rebuilding but you need to tune on the engine , the bad news is this is not going to run well Comp Cams are not great & the combo of a 110* cl & stock manifolds is not going to work well at all .

 

[Bret Schneider]

Since the car ran OK in the past I think your best bet is to just disassemble the carb, clean it making sure that all the small passages are clean. Compressed air and shooting carb cleaner through them to make sure there aren't any obstructions works the best, at least that's been my experience. Any changes to the jetting / accelerator pump should be made once the carb is reassembled and back on the engine with the car running otherwise it's just a guessing game.

How And When To Change The Jets On A Holley Carb

One thing you will want to do with the carb off is to adjust the accelerator pump arm travel. Way easier to do it now rather than later and chances are it will need tweaking.

Accelerator Pump Tuning For Holley Carburetors

 

[72pistolgrip]

I agree with rebuilding but you need to tune on the engine , the bad news is this is not going to run well Comp Cams are not great & the combo of a 110* cl & stock manifolds is not going to work well at all .

Ugh. Why is that? I have mild comp cam on 72 340 challenger with holly. Thanks in advance

 

[Xcudame]

"Ugh. Why is that? I have mild comp cam on 72 340 challenger with holly. Thanks in advance"

Comp Cams are just OK. There's much better camshafts like Lunati Voodoo cams! Custom ground cams to go with all your other parts are probably the best.

 

[Chryco Psycho]

The combo of a 110 * LSA allows too much overlap , long tube headers will create a suction behind the exhaust leaving , in a manifold this is not possible , it will run far better with a 112* lsa or more