Like the title says, were there more than one design. Namely for a 95 Vette.

383 project, need to purchase an SFI approved flexplate and I'm confused as to why the machinist would ask which flexplate it has.

Does anyone have some insight on this or can offer some advice on what to use. This isn't my motor and I'm not sure whether this guy needs a neutral balance flex or stock. Is there such animals?

Oh yea, and are there teeth count variances?

 

The 383 is an offshoot of the old 400. All the original 383s used a modified 400 crankshaft. 400s were externally balanced. Unless someone paid extra for an internal balance job, the counter weighted flywheel and damper from a 400 were used to complete the balance job. Back in the day, before 1986, with the 2 piece rear main seal, 350s were 100% internally balanced. Since 1986, the one piece seal cranks got a different flywheel flange. 350s are no longer 100% internally balanced. There is a slight imbalance in the rear, only, due to the different flange, which is made up by an unbalanced flywheel or flexplate.

Now that the the history is behind us, there are a few questions that need to be answered. Was the 383 "internally" balanced? Was it a 100% neutral balance, or to one piece seal specs? Is the new flexplate 100% neutral or one piece seal balanced? If the rotating assembly is not internally balanced, the flexplate will have to have a "400" unbalance. No 400s were ever made with a one piece seal, so there is not "stock" plate for this. If there isn't an aftermarket flexplate made for whatever it is you need, it will have to be balanced specifically for your engine. IF the flexplate ends up with a "special" balance, get the specs of that balance, so it can be duplicated in case a replacement is ever needed.

And just to complicate matters, more, all 400s came with 168 tooth 'wheels or 'plates. All C4s have 153 teeth. So of course, therefore, there never was a stock 153 tooth, anything,with the 400 balance. And stock starters don't interchange between 153 and 168 tooth 'wheels. I hope all this helps shed some light on the situation.

RACE ON!!!

 

Thanks so much CFI-EFI, it would be easier also if I wasn't working with second hand information also.

I told my friend to sign up here to make things easier and for the wealth of knowledge that abounds. I sent him the link to this this thread, maybe this will give him some incentive to sign up and say hi.

I have my own issues to deal with, but I'm not above trying to help someone out.

If it were me, everything would be neutral balanced and I'd be done with it. Then I'd imagine, any performance balancer could be used.