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MGB Motors

Started by JohnTwist, August 09, 2022, 12:37:51 PM

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JohnTwist

I have two 1800 MGB motors: one a 76 and one a 79. The 76 uses two alignment pins and the flywheel is drilled for two pins. The 79 crankshaft was drilled for two alignment pins but only one was used. The flywheel was only drilled for one. Can I use the 76 flywheel on the 79 without adding another alignment pin? How will it affect balance?
Shannon

By the late 1979 and 1980 models, the crank and flywheel had only one alignment pin.  Whether to make fitting foolproof or to save money is a question.  You can certainly use the two pin flywheel on the one pin crankshaft.  BUT -- be certain to fit the flywheel correctly.  The flywheel is marked with a 1|4 on the circumference.  Fit that mark at 12:00 when the #1 & #4 pistons are topmost. 
There is no assurance of balance after swapping out flywheels.  Yet, I've never seen a problem I'd attribute to swapping flywheels.  Interestingly, Glenn Lenhard of Glenn's MG Service in St Petersburg, Florida tested about ten flywheels on his zero friction tire balancer.  ALL, again ALL, of the flywheels he tested came to rest with the 1|4 topmost. 

Luck of the draw or did the factory make them with a slight imbalance?  It is always best to have the crank/flywheel balanced when rebuilding and engine.  If it's just a matter of spending $50 to have your old flywheel resurfaced, I'd spend the money at the machine shop.  Hope this helps.

SAFETY FAST!
John H Twist
University Motors Online
100 East Beltline Avenue SE
Grand Rapids MI 49506-2410
Cell  616 307 6737
www.universitymotorsltd.com
SAFETY FAST!
John H Twist
University Motors Online
100 East Beltline Avenue SE
Grand Rapids, MI  49506

616-307-6737
johntwist@universitymotorsltd.com
www.universitymotorsltd.com

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