buick 340 flexplate

**rayy08** · 01-08-2014, 09:04 PM

help please
I appear to have lost the flex plate to my 1966 buick 340 engine while it was being reconditioned... can i just buy a new or used one and put it on as is ? or does the crank have to come out to be rebalanced ??

**Dr. Frankenbuick** · 01-09-2014, 04:07 AM

The entire rotating assembly should be rebalanced with the flexplate and dampner if you replaced the pistons or rods with anything other then stock replacements (with the same weight). You should be OK with a used original 340 flexplate if you used stock (weight) replacement pistons or rods.

**rayy08** · 01-09-2014, 02:58 PM

Originally Posted by Dr. Frankenbuick

The entire rotating assembly should be rebalanced with the flexplate and dampner if you replaced the pistons or rods with anything other then stock replacements (with the same weight). You should be OK with a used original 340 flexplate if you used stock (weight) replacement pistons or rods.

yes the pistons were replaced ...

**Dr. Frankenbuick** · 01-10-2014, 04:36 AM

Do you know if the pistons were stock, stock replacement or stock weight? If so, a used 340 flexplate would put the rotating assembly where the factory had it for balance. That would be fine for stock rebuild. It is a different story if you will be turning up the RPMs or racing it down the quarter mile. I always have my rotating assemblies balanced as I know I will have to see everything it has one day. Even if it starts out as a stock rebuild. I just can't help myself (at over 50 years old no-less).