holley 750 double pumper?

Question

Holley 750 double pumper carb?
i have a 750 double pumper on a ford mustang 302 and its fouling the plugs and a guy at a local ford shop told me its to big of a carb i have e-303 cam gt-40 heads 1.7rr full msd egn. barry grant fuel presure regulator he also told me if i jet it down that it would work fine he said he just done the same thing for a guy and it worked fine,but hes out of town now and i need to no do i need to change the squirters also i have #31 INSTALLED NOW.

Answer 1

The best way to fix this problem is to re-jet, next would be to replace it with a 600 or 650 at most. You never know the out come when you start playing around unless you dyno the motor. Running an engine on the dyno is about the cost of a carb in the first place (for 1/2 a day), many benefits though, oil pressure, VE, Hp, tq, Air to fuel ratio and in your case way to rich. plus a hole lot more, I could write a book on dyno testing, it's a must if you go into the engine, pistons, cam, lifters, valve springs, heads, intake and carburator..etc.

To of the biggest mistakes is over carb & over cam for an application.
Every motor I build goes on the dyno or I tell the person take it somewhere else.
(77)

Answer 2

Try everything your shop recommended. I'd like to suggest the following. The only 302's that ever used the double pumpers were the ones used in road racing in the 60's. They operated in the 5,000 - 8,000 rpm range. You may find company's that offer delayed secondary throttle pick-ups that will allow you to run on the primaries 80-90% of the time. If you're using the MSD ignition there's none better but it's pretty obvious you need smaller squirters and smaller jets. Do the squirter thing first and keep reading plugs. If the plugs are still black drop a couple of jet sizes at a crack to lean it out. Depending on your idle inches of mercury *(vacuum) be sure your power valves are at least stamped with numbers a minimum of two numbers LOWER than your vacuum at idle For instance: If your idle vacuum is 7.5 inches of mercury install both power valves with 5.5 stamped in the side of the sides. This helps to give you a cleaner fuel mixture with the motor while idle. Try these things first. If they do not work find a vacuum secondary 650. You can play with secondary tip-in openings with different variety's of springs. You'll love this Holley I'll guarantee it. 360 dirt circle track Chevrolet motors scream on up to 7,500 rpm's with the double pumper 650's.

Answer 3

trade it for a 650 double pumper. My 502 aluminum headed big block Chevy had a 650 double pumper on it and ran hi 11's in the quarter with 66 and 72 jets. otherwise just jet it down till the plugs burn cleaner. everything on a Holley is easy to do . don't be intimidated by it. once torn down you'll see how simple they are to rebuild. go to your library they have Mitchell books to show you how to rebuild your carb if you don't know how to do it yourself. ask buddies usually one of them will know how to rebuild one for you.

Answer 4

go with a 600 or 650 cfm that is all the carb you need you are not burning the fuel that goes through the engine only part of it

Answer 5

Your running too rich..... turn in your lean/rich mixture screws until the engine runs rough then turn them out till the engine runs smooth again..... that will set it just right.

Answer 6

that thing is way too big , get a 650 single at the max.