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phoenix499 07-15-2008 09:41 PM

holley carb issues

I have posted here before but its been a while. Bought a 1969 Chevy C10 a while back and I have been tinkering with it here and there. I have a holley 4 barrell (I am unsure of the specific model) with an edlbrock intake. The engine is a 350 MD out of a 73 gmc.

I'm sure someone is going to read this and say to themselves: "What a friggin idiot." But hey, the only dumb question is the one not asked. Right?

So anyways the truck runs like a dream up until i hit about 65-70 MPH. Then it starts acting like it is running out of gas. When I let off the gas a little it stops, but if I get back on it it does it again. Does the carb need any adjustment, or just a good cleaning? I will be driving the truck from Alabama up to NC soon. Most of the trip will be on I-85 and I would hate to have to drive it all the way up to NC like it is. If anyone has any suggestions I would appreciate it.

solidaxel 07-15-2008 10:48 PM

You might try and raise the float a bit.
Go up on the jet size by 2 numbers
change the power valve to a 6.5.
Try the easiest first!!
Only make one change at a time then test.

SSedan64 07-15-2008 11:14 PM

Check your fuel filter and fuel pump pressure also. Does it do this if you get on it hard just taking off from a stop when the rpms are high?

phoenix499 07-16-2008 10:41 PM

well, i set the idle screws back to the initial setting and that seemed to clear the problem up(they were both set WAY out so i guess the fact that the idle system was unbalanced may have had something to do with it). I went to and looked at some of their onine manuals and got some good info from there. Ill probably check out autozone this weekend and snag up a vacuum meter and make some adjusments and see what I come up with. It does stutter a good bit when i take off from a stop. but i think i found the fix on the website. thanks for your replys.

techinspector1 07-16-2008 11:10 PM

The first thing I think about when someone posts these symptoms is that the valve springs are toast. Of course, I could be wrong.

JeffB 07-17-2008 12:30 AM

Holley tuning
It almost seems that you may not be getting the secondaries opening,if your Holley has vacuum secondaries you may want to check the diaphragm's condition and make sure the spring is in there.

phoenix499 07-17-2008 09:53 PM

thanks jeff, and tech
I had a similar problem with a 68 I had backin HS. I remembered my dad telling me the only problem was that theflaps were stuck open. (It was alot worse with the 68). I'll definitly check it out tommorow.

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