GaryBisiniere

thanks man i hear ya i love the 750. how can i tell if its the accel pump. ill open it up tommrow and check the gaskets.

1985stang

lol, no ****. I'm not a carb expert by any means, but I know enough to say that 750 is way, way, way too much carb for a 302/306 (same thing basically).
http://holley.com/data/TechService/T...Carburetor.pdf

67mustang302

Ok, first of all, there's NO WAY your engine is going to pull anything even remotely close to 750cfm unless you're turning it at more than 7,000rpm and a VERY well built race 302 n/a. That means you're going to ALWAYS have airflow velocity problems(and hence, atomization problems) especially at part throttle. Second, your accelerator pump cam, squirter, power valve, jets and secondary spring all have to work together. It's not as simple as "Not enough pump cam, or too much pump cam" etc. You may have too big or too small a power valve, you may have too big or too small of a pump squirter, you may have too much or too little initial/overal pump cam duration, you may have too much or too little jetting, too much or too little secondary spring pressure, or a combination of the above. And like I said, since your air velocity sucks because of too much carb, even if you get the right amout of pump shot and the right power valve, you'll still have problems from time too time because the low velocity and low vacuum(at lower rpm)in the manifold will cause the fuel to fall out of suspension and lean you out, or have wet fuel run into the cylinder and not burn, and you'll get crappy atomisation which means ineffective combustion and a loss of power. There's guys running cars well into the 12's in the 1/4 with 600cfm and smaller carbs on 302's. Can you tune your 750 to run ok? Yeah, I'm sure you can. Will it ever be as fast and efficientas if you have an equally well tuned carb of proper size? Nope.

shawnk007

go to holleys website. i believe they have a chart that will match you up as far as what size u need for your mods. but, i agree with the rest of the crowd....750 is WAY to big!!!! why do people always think that bigger is better???

Gary H

Sounds like a stuck float, or dirt in it. Check the needle valves. If it's running rough, look in the carb and see if gas is dripping from the boosters.

scrubadubb

yea i think it's too much but if your intent on keepin it check the accelerator pump. holleys are well known for those little diaphrams blowing. a backfire could cause it to blow.