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MG MGB GT V8 Factory Originals Technical - V-6 conversion vibration


I have a 2.8l chevy in my '77 MGB. At 3500 rpm and over the engine has a HUGE vibration, any ideas.
jim johnston

The most common cause for a vibration of that magnitude on a 2.8 is an internally balanced crank using an externally balanced flywheel, or visa versa. I used to know all the casting #'s for the various years of 2.8's (many running changes) but I rarely see those cranks anymore,and memories fade. Bill G. can probably shed some light.
Dale

2.8's from 1982 to 1987 are externally balance. Keep in mind that some early 88 are externally balance, regardles of what they said.

Dale is correct, if you mix-match crank and flywheel you will get a very harsh vibration. The fix would be to find out which flywheel you have. The externally balance engines use a flywheel with a big weight casted in the flywheel the internally balance the flywheel is neutral balance, no big weights on it etc. It may have some small holes in the outer part for balance of the flywheel.
Get the correct flywheel and you will be in bus.
The best place to get a flywheel is NAPA $80-90 recondition. You may also check the damper, the externally balance engines have neutral torsional dmapers. The damper and flywheel go together as a match.

If interesred I can tell you how to remove the trans without taking the engine out.
Bill Guzman

look here to see a flywheel for an early engine and you can also see the crank from that engine.
http://www.mgbexperience.com/phorum/read.php?f=40&i=1029&t=1029
andy heston

Thank you all for the help, the tranny comes out tomorrow. It's a 85' engine so I'll see what I have for a flywheel.
jim johnston

Jim,
Probably too late to tell you this, but you could take the inspection cover off and the starter down and look for the flywheel counterweight (or the lack thereof) without pulling the motor.. Those pictures mentioned above are very good pointers for what flywheel you may have.

-Brian Mc Cullough.
BMC Brian McCullough

This thread was discussed between 30/10/2004 and 04/11/2004

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