David Ey

Well, 750 Holley still leaks gas when I turn off engine. Added the heat shield as suggested by Lars and a 3/16 fiber spacer under carb and there is no change in the leakage.....leaks out about an ounce or so on each side of carb.
Does anyone else have this problem and is there a better choice of carb? I am at the maximum height now and don't want to put a hole in the hood.

MoneyPit

I was having terrible problems with my 650 Mech Holley. I could not figure it out. There always seem to be trash getting in the needle and seat which in turn caused similar problems you are having. I adjusted float and everything else twice, and put two rebuild kits in it. Then on a whim, I removed the inlet plumbing (the two fittings which allow you to hook your fuel lines into the bowls. My car (and carb) sit up alot, as I am slowly restoring the MoneyPit. Overtime, both of the inlet fittings had corroded severly!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!. The chunks of rust would choke the fuel, then they would break loose when I tapped the bowls and enter the needle and seat. Then old faithful would spit out about an ounce of fuel. I did not read the previous threads on your problem, but you may want too take those fittings off and get new ones or clean them if they are corroded. Just a thought.

Tim H

Maybe the arm that pushes open the fuel diapram is too tight and pushing open the pump?
While sitting (engine off) adjust it until it doesn't touch then see if it leaks, I think they are sopposed to have about .020 clearance anyway?

Fastguy

Where is it leaking from? I have seen a ton of Holleys leak from people substituting a garage door spring for the throttle return spring. It wears out the shaft bushings and causes leakage on the throttle shaft.

stingr69

Don't do that. The pump arm should not have any clearance. If you have any clearance the car will have a flat spot at tip-in.

The adjustment is supposed to be set so you have zero clearance at idle AND have an additional .015"-.020" available extra travel at WOT so you do not bottom out the pump when you have it at WOT.

This adjustment has nothing to do with the problem of the OP.

David,
You might try to lower the fuel float level a bit and see if it helps.

-Mark.

eastltd

Is the carb hot to the touch? Could be the cross-over ports in the intake gasket were not closed off and you're getting hot gases crossing under the carb. The intake gaskets come with metal close out tabs that reduce this problem. If they were not intalled you get a lot of heat at the base of the carb.

682XLR8

Fuel boil-over was a persistant problem on my 327. When I installed the 383, I used a head/intake combo that had the exhaust crossovers blocked, and fuel boiling has not been a problem with this motor. So I'd try blocking the crossovers like eastltd suggested and see if that cures it

Tim H

First you will need to check the adjustment on the pump. To do this you will open the throttle all the way (WOT). Push the pump arm lever down and then adjust the pump override spring to obtain .015" clearance between the pump arm and lever.
Above strait from the holley website!

stingr69

The Holley web site is right and that is what I posted as well. It is not what you posted the first time.

Again - it has nothing to do with the OP's problems in this thread. Lets just stick to the topic at hand and try to help out.

-Mark.

Tim H

If its wrong at WOT then it is wrong at idle, the adjustment just happens to be at WOT instead.
Mine was dripping a little and I adjusted the pump arm and it stopped leaking.

ShinodaVette

A friend of mine just went through this with his Holley. I'm not a carb expert but I know that after him talking with Holley many times and adding heat shields, spacers, changing out some part they suggested was wrong for his engine on the carb, adding fuel pressure guages to prove it wasn't a pressure problem, and even sending the new carb back to them for a check-up that turned up nothing it still had the exact same problem. Finally he convinced them to replace the carb with a new one and the problem magically disappeared.

Is this relevent to your situation? Maybe, maybe not but that's what he went through. I guess my only real point here is that after trying everything you and others can think of, if it still has the problem it could be the carb itself. For what it's worth.......

Hope you get it worked out!