NHRA (and RMR) don't require an SFI approved damper until you run 10.99 or quicker. IF your present damper is a stock 400 damper, and wasn't altered during the balancing, another 400 balance damper should readily interchange. But it would be wise to verify the amount of imbalance, between the two, before you install the new, smaller damper. On the small block 400, the imbalance is on the outer ring. On the big block 454 the imbalance is on the hub.

RACE ON!!!

 

You might want to hang around for some of her spelling exercises...

Larry
code5coupe

 

so I just need to take my new balancer and old balancer to a machine shop and have them compared. and modified if nessesary

 

Its hard to type when she is on my lap and she press the keyboard

Didn't know that you can the rear internal balanced and the front externally balanced. I thought it all or nothing.
SFI – My machine shop suggest this to me for cheep insurance.

 

YES!



All two piece rear main seal small blocks, except the 400, are 100% internally balanced. Both the damper and flex plate or flywheel are "neutral balanced". That is balanced unto themselves. Because of the longer stroke and the mass of the crankshaft, the 400 engines are "externally balanced" That is, there is unbalanced weight on both the damper and flex plate or flywheel, to make up for weight that isn't present on the crankshaft. Essentially, a 383 is a 350 block, fitted with a 400 crank. Unless special provisions are made, the 383 needs to use the 400 damper and 'wheel. New cranks designed and built for 383 conversions can be made heavier in the counterweights or any crank can have mallory, "heavy metal" added to the counter weights to make them internally balanced. Internally balanced rotating assemblies take the 350 type neutral balanced accessories.

Just to complicate matters, in 1986, when the one piece seal was introduced, the rear flange of the crank had to be revised. The rear of the crank lost the external counterweight and the bolt pattern changed. This required that all '86 and up 350s have an unbalanced flex plate or flywheel. These engines take a neutral balanced damper. This throws a monkey wrench into the "neutral balanced" stroker kit equation. If the neutral balanced stroker is truly "neutral balanced", there is no flex plate or flywheel for it. Chevy never made a neutral balanced 'wheel with the one piece seal bolt pattern. I don't know of any set up that is balanced in the rear and unbalanced up front, but most C4s (1986 and up) are just the opposite.

RACE ON!!!

 

Hey thanks Jim By the way are you going to be at RMR next Saturday? if so I'll see yah there

 

No. It doesn't look like I'll be racing this year. You DO mean the 16th, right?

RACE ON!!!