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5.0 vibration problems

883 Views 6 Replies 3 Participants Last post by  5.0 saddle club
Just installed a brand new 310 in a 91 lx efi. The engine is at 4,000 and coming down from a rev just before idle. Installed new balancer. Took the clutch back off and still have the problem. Need ideas ASAP
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A 310? What is that, bored .060 over or something? I know .030 over is a 306..
was the engine assembly balanced? motor mounts look like?
.60 over yes it was balanced. 24 lb injectors 73mm mass air track heat intake w slavery. Mounts looked good. It does it when you bring it past 4000 and also around 2000 rpms when coming down from a rev. Its like it vibrated before it settles to an idle. We put a new balancer flywheel clutch pressure plate and still does it. Could the mounts be causing this or maybe cause the computer hasn't been tuned?
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Intake w spacer* sorry I'm on my phone and had a spell check lol. I'm at my wits end with this. About to pull it back out and put a different one in.
And the new balancer and flywheel are the 50oz imbalance...not 28oz?
Yes sir, its an older model block converted to roller with 50 imbalance crank. Professional products balancer and new flywheel. We thought maybe they didn't use a 50 imbalance crank but we checked it and the flywheel bolt holes go all the way through. We are to the point of building a whole new setup and sending this one back to be checked.. I their must be something wrong with the internal balance of the motor.
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