if you go from a '90 block to a '83 block.... will you have to use a different flexplate?

 

Yes

 

would the '83 flexplate work here?

 

no. the two flexplates "do not interchange" and therefore, you'll need the two piece RMS flexplate.

 

can you elaborate?

 

I'm guessing you're putting the 83 motor into the 90 car....

The 83 flex plate may work with the 83 block, if it's the right diameter for your starter. If it's the other diameter than what your starter is for, you'll need another starter.

 

you're right on the money, RB83L69!! What do they measure starters by? a certain number of teeth?

 

You just have to look at them and identify them.

The one for the 153-tooth setup is smaller than the other, and the motor lead sticks through the case in the smaller part of the case, right near the brush cover, and the bolts are in line across the back of the block. The starter for the 168-tooth stuff is larger, the motor lead comes out of the larger part of the case before it necks down to meet the brush cover plate, and the bolts are in a staggered pattern.

If it was my car, I'd probably want the smaller setup; the starter is a weenie POS, but it gives 5/8" more header clearance. The weenie aspect you can fix, with an aftermarket starter.

 

It seems I have the weenie 153-tooth setup. In theory I should get a 153 tooth flexplate for the 83 block?

I should have kept that L98 block

 

ok... i just realized someting: I should not tryhelping anyone when I'm on my meds. (painkillers/muscle relaxers) disregard anything i said/say, until my back gets beter. (i hurt my back which is why i'm on narcotics.) anyhoo, good luck with your project.

 

There are different part numbers for two piece and one piece rear main seal flexplates. Don't know if there is a difference, but I'd stick to what block I have.