I recently purchased a holley 750 vacuum sec. carb from a guy for my BBC454 and am having troubles getting my car running. I have a jegs fuel pump (105gph) running to a holley regulator to the carb. I figured out through a series of tests that I am getting too much fuel and is flooding my engine. I have been having a really hard time getting the regulator to stay at 6 psi. It seems like the F/P is pushing too much fuel. I set the mixture screws to factory. Set the float levels. and it still bogs and won't start. When I disconnect the fuel line from the carb, it runs great off of the fuel in the bowls until it runs out. rehook-up the fuel line and it bogs and won't start. The guy I purchased the carb from said he put in 72 jets. Is that too large and flooding the carb or could it be the needle/seat? Any help is greatly appreciated. PS. have e rebuild kit on the way!!!

 

I would start with a full rebuild as planned. Put the carb back to stock as per Holley spec. Look up the list number on Holleys site. This is where I would start before going any further...

It sounds to me like a bad needle and seat. Is that pump electric or mechanical?

 

When you say it is flooding and you have a hard time keeping the fuel pressure at 6 psi, I assume that means it is going higher than 6 psi - is that correct?

If it is flooding at a pressure lower than 6 psi, then you have a needle/seat/float problem.

Otherwise, you have a regulator problem and need to correct that first.

 

It's a electric-JEGS 105GPH with the holley regulator. I have a guage on my fule line. I was getting like 9-12 psi at first. I tried turning the regulator down but that didn't work. I hooked the fuel line up to a handheld guage and was getting about 8 psi. I think maybe I got a bad regulator. I drained my oil yesterday and it had a ton of gas in it- I guess from all the hard starting/flooding. Could this mess up my engine? I took apart the carb last night and found a bad power valve valve gasket. This particular carb ran with 70 jets . It has 72's in it right now. I figured that that may be another reason it is getting too much fuel.

 

Yes excessive gas in the oil can do damage. If the fuel regulator is new enough return it. If not I believe the repair kit is cheap enough, better safe than sorry.

http://www.jegs.com/i/Holley/510/12-...oductId=745059

So with this bit of news I do agree with 57, part of your problem is the regulator.

But, a bad PV gasket will amplify the problem once fuel pressure is present so that repair is indeed needed either way. That explains why removing the feed line would allow the car to run. Excessive fuel pressure from a bad regulator and a bad PV gasket allowing it to flood the carb out. Fix these 2 problems and let us know how it runs from there. 72 jets have very little impact at idle over the stock 70's so no worries there. Concentrate on the main problems to get it to idle properly, then jets can be addressed.