rough running 302

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Feb 1, 2011 | 03:12 PM

down2earth1928

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Joined: Aug 2009

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From: butlerville,arkansas

rough running 302

I have a 1977 f100 302 auto.I have a fresh rebuilt moter.It sounds great at idle but when you give it gas it starts running rough,rough enough to start making the truck vibrate.It seem when you get the rpms up high it smooths out some.any ideas what may be the problem?

Feb 1, 2011 | 03:42 PM

fordman400

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Joined: Oct 2003

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From: wisconsin

Sounds like a timing issue and carb needs adjusting. What size carb are you using? Check fire order and timing.

Feb 1, 2011 | 04:03 PM

joerickson

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Joined: Jan 2010

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Also check to see if the carb is leaking anywhere. Mine had similar issues (except only under load) and it was because of the accelerator pump leaking.

Feb 1, 2011 | 05:10 PM

down2earth1928

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Joined: Aug 2009

Posts: 69

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From: butlerville,arkansas

It has a 2 barrel on it.I ordered a new one should get in a day or two.I couldnt find any leaks but I did find a little vacuum leak when sprayed with carb cleaner on passanger side.firing order is correct.timing is good.the vacuum leak was very minimal.hard to hear a change but there was some change.