Holley Help

Dual 390 cfm Holley 8007's (vac secondary, similar architecture to the 4160) on a tunnel-rammed 5.0L H.O. 302. Carbs have been completely rebuilt. Car runs great, but for reasons I do not understand, the floats stick at the strangest times. I drove the car on Saturday -- it had been garaged for a month. It fired right up, idled great, ran well. I drove it all day. Garaged it, went out tonight, and started it. It started with a touch of the key, idled great, I let it warm up while I took the T-tops off, and after about a minute of idling, it started running rough, died, and I smelled gas. :mad:

I took the scoop off and fired it up again, and saw that the rear carb was leaking gas out the lock screw / fuel level adjusting nut assembly for the secondary metering block (8007's have metering blocks for the secondaries, but there's an adjusting screw identical to the primary bowl) and was pumping gas out of the secondary bowl vent. I loosened up the screw and fuel level adjusting nut, retightened it, and that solved it, temporarily -- I started it again, it ran for another 10-15 seconds, and started coughing again, this time spitting gas out of the adjusting screw and bowl vent for the primary metering block of the same carb. :CRY:

It was doing this last winter, too. I tore the carbs completely down at that time, both of them, replaced the gaskets and reset the floats, and it ran great. Now, it's doing it again. I am one busted knuckle away from chucking them both and replacing them both with Edelbrock 1403's, but the glory of running dual Holleys is just too sweet to give up. As yet.

Any ideas what's causing this? The last time (I haven't taken it apart this time, yet), I just backed the fuel level nut / locking screw assembly out and back in, and that solved the problem; this seemed to do it for the secondary metering block this time, too, but I was in a hurry and couldn't screw with it any further. One time before -- last winter -- the float seemed to be actually jammed; I took the bowl off and the float worked fine after I took the fuel level nut/locking screw assembly all the way out and shook it around. This has happened on both carbs but it seems to happen more on this one.

Any ideas?

fuel psi creep? at idle had this on 4500 carbs went to to two fuel regulators or a big mallory or etc regulators. at ilde you do not need much fuel psi so a by pass or a good fuel regulators help .this if no by pass then you need a big regulator or i have used to holley. blues you are sinking the floats with to much fuel psi

That might well be the missing piece to the puzzle.

Would I need a fuel pressure regulator on each carb, or can / should I run a "Y" out of the regulator to both carbs? I'm using a Holley mechanical fuel pump "for street/strip applications" :rolleyes: rated at 8 psi.

And wow, this site looks nice!

Try the following site for technical help on your carburator:

http://www.holley.com/

jc::toocool:

Pic of the offender attached.

I did install the fuel regulator, and it makes a huge difference. The gasket on this piece (below) had separated and was hanging up the needle valve. This explains why the problem was intermittent. The flooding of the bowls was probably a fuel pressure issue. This is the umpteenth time that I've had my @ss kicked by two or more problems happening simultaneously.

Resurrecting this thread. Probably unrelated but here goes -- round six or seven with these $#!%%&ing carbs.

The car was idling weird -- kinda lugging, from 1500 down to 900 (1500 is the normal cold idle in Park.) I shut if off, took off the scoop and air cleaners, checked vacuum lines, checked the chokes (the butterfly on the foward carb had stuck closed a couple of weeks ago), everything looked good. The rear butterfly valve seemed a little too open, so I adjusted the choke to even it out with the front.

Fired it up again, idled it for a few seconds -- seemed to idle great, now -- dropped it into reverse, and BOOM!! Engine dies, backfire and flames. Big flames coming out of the rear carb.

Here's what I don't understand -- why would it idle fine, and then blow up when it's dropped into gear? I'm going to rip that carb apart in the morning. I know I at least need a new power valve. . . .