I'll let him tell you.

Hi, it has been quite a while since i have been on here, but i need some body who knows holley carbs.
I have a 600 cfm holey on my 289. I have taken the carb off 4 times to rebuild it in the last 6-8 months. I keep having problems with it dieing or not having power. I think i fixed the power problem but now it wont stay running if i let it warm up for a while and it will start to slow down till it dies or if i am driving and pull up to a light and put the clutch in it will some times die and some times it falls on its face and comes back up to idle. Also when i start it it kind of has a thu thu thu or chug chug chug then it smooths out after fireing a couple of revolutions. Also if i put the peddle down WOT it back fires. I have the standard size jets in it and the power valve is one that came out of a walker brand carb kit. What will cause my problems and how can i fix them. could the timing beeing too far advanced cause this or maybe just the back fire.
Thanks,
Jarrod

Try to help this pathetic excuse for a Shelby run!

TTT

is the fuel pump good?? is the timing set right?

<font face="Arial,Verdana" size="2">Originally posted by 1981coupe400ci:
is the fuel pump good??</font>

Good question! It's a parts store replacement, and probably has a good 6-8k miles on it. We are going to retime it as well.

It sounds like its running lean... the backfire through the carb when you stomp it from idle is a good sign of that. I'd suggest changing the jetting, kick it up two sizes on the primaries and see if it helps. Also, check the adjustment of the accelerator pump lever, and the condition and type of accelerator pump cam you are using.

I had a similar problem (the lean bog/backfire) with my Holley not too long ago, and the problem was the accelerator pump lever. It was adjusted way too loose, and had some play in it. What I ended up doing, was (on the throttle lever/pump cam side) bending the acc. pump lever down just a little bit, so that there was no play between it and the pump cam. Cured.

Holley does reccomend keeping .010" clearance between the lever and cam, but I've found that the engine just runs better with 0 clearance. The throttle resonce is just much better that way.

Well there is 0 play in the pump lever, and it has the biggest cam you can put on one (yellow, or yellowed white, probably the ladder). So should we look into jetting it up?
My brother is going to be pissed!
We've rejetted this thing more times than I can count! Except we'd been jetting it down because we thought it was running to rich, black puff at WOT. But we leaned it out WAY to much, so we put it back to where it was. So now you think we need to jet it up?

I'm not sure bigger jets will help a WOT tip in lean hole problem. I would try bigger accelerator pump discharge nozzles first, unless you already have the big ones(.035) in there.

Falling on its face at a stop, then coming back, can be indicative of a float set too high.

Are you checking pump clearance at wide open throttle or at curb idle setting? At wide open throttle you should be able to push the arm down another 15 thousands of an inch. As far as it idleing and then dying, you might have a small vacuum leak.

I think we got it fixed!

Thanks guys!

what was it?????

<font face="Arial,Verdana" size="2">Originally posted by bryan1970:
what was it?????</font>

a FORD.....