390 4bbl very difficult to keep running

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Apr 22, 2005 | 10:06 PM

reamer

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From: Connecticut

390 4bbl very difficult to keep running

Hi all,
I'm usually on the '49, or '86 forum, but my '74 suddenly wants to mess up.
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It will start roughly and die. Crank and crank, the only way she'll start is hold the gas to the floor and crank. It will start roughly, like 4 plugs aint firing.
If I hold the choke open, it will run smoother but still rough.
Lots of blue, but rich smelling exaust.
390 was re-built 2 years ago, I know the internals are good.
As it warms up, it's smoother.
Carb? egr? should I pull a plug?
Thanks
Reamer

Last edited by Torque1st; Apr 23, 2005 at 03:21 PM.

Apr 23, 2005 | 06:21 AM

76supercab2

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Joined: Feb 2003

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Carb. There shouldn't be an egr unless you put it on. Probably the choke is misadjusted. That year should have the electric choke on it. When you floor it, the choke blades are pushe open slightly. This is to help clear a flooded condition at cold start. If this is the stock holley 4bbl, try rotating the black plastic housing on the passenger side of the carb to the 'leaner' or '-' side. I think that's counter clockwise. If you watch the choke plate you will see it move when you rotate the housing. Rotate it so the choke plate opens more.

If it continues to run rough after warmup you might need to put a rebuild kit in the carb. The power valve could be blown.