Figuring out imbalance for flexplate?

[NUTNDUN]

Hey gang,
I am slowly getting everything together for my truck and have come across the next dilemma of the never ending saga LOL. The motor is a 69 windsor block and it is stroked to a 398. I need to figure out what imbalance flexplate I need to get. I know the 351 windsors are normally 28oz but there is the possibility that it was zero balanced when the motor was built however many years ago. The only information I can provide is that it has an ATI race super damper and it has on it that it is zero balance and to drill the weight on the back to set imbalance and the weight on the back isn't drilled. Maybe that makes it obvious but I don't know enough to be sure. The other things are is the counterweight on the crank has been drilled at a couple different spots.

[Ranchero50]

You are probably screwed... I'd try to find some numbers on the crank or take it to someone who does this style motor to see if the throws have balancing holes etc. I'll take a WAG and say zero balance, but you never know. I know that the billet FMS flywheel has bolt on weights so you can go from 0 to 28 to 50 as needed. That's what's in my mustang.

Jamie

[NUTNDUN]

I got the part numbers off of the ATI damper and it is showing on their chart on their website that it is external imbalance and on the chart all the way on the left it shows:

V8 SB
ALL FORD EXCEPT '82 & UP
302 HO
28.2 OZ.IN.

Here is a link to their chart:
http://www.atiracing.com/products/dampe ... amford.htm

The part number that's on the damper is 916562

[Ranchero50]

Then you 'should' be ok with a 28oz flywheel. That's weird though because usually a good balancer guy wants all the crank components from the pulleys to the flexplate

Jamie

[willowbilly3]

You bought the motor built? Does the seller have a flywheel/flexplate? It should have been balanced with the engine on a custom build like that.