68 302 shakes badly at idle.

tevans720

New Member
Apr 22, 2010
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Minnesota
Ok I have a 68 302 in a 80 Mustang did a T5 swap from a auto. After finally getting everything I need and finishing it when I start it it shake something horrible at idle (between 800-1100rpms) After that it runs smooth as can be all the way through each gear.

My first thought was balance since I changed out the flywheel. I need a 28oz fly for a 68 so I picked up a fly from a 63 fairlane 289. THAT'S ALSO 28OZ RIGHT? To double check I took a look at the flex plate casting #'s got a C5AE which I believe is a 65 generic full size ford. ALSO A 28oz RIGHT?

What can it be? after 1100rpm its smooth all the way to 5500rpm haven't gone any higher don't see the need to.


Help! Having problem after problem.
Tyler
 
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did a previous owner change the rotating assy. in the engine to a newer 50oz balance? if you have another flywheel, I would swap it in and check to see if it is better. I know that you can only put the flywheel on one way, but maybe there is a flaw in the one you have. Just an idea.
 
did a previous owner change the rotating assy. in the engine to a newer 50oz balance? if you have another flywheel, I would swap it in and check to see if it is better. I know that you can only put the flywheel on one way, but maybe there is a flaw in the one you have. Just an idea.


IDK but the flexplate that was in there had the C5AE code so I'm like 99% sure it a 28oz. But the flexplate has 2 other weights welded on for a total of 3 it could have been rebalanced.

Is there a way to look at the damper (harmonic balancer) to see what balance it is? Like a casting code or stamped 50oz or 28oz.