I'm building a 350 using a 1991 block, so it is a 1 piece RMS. However my balanced bottom end just arrived, and it turns out the wrong kind was ordered so now I have a crank for a 2 piece RMS.

I'm told you can just order an adapter and then go ahead and use the 2 piece seal. This sounds fine, as long as it works correctly. Apparently all you need to change with the entire gasket set is the rear main seal.

My other question is flywheel related. I now know I can't reuse the flywheel off my old 91 350 (regardless of crank style) since that is weighted for an external balance and my new assembly is internally balanced. Can I simply find an older flywheel which is designed for the 2 piece sealed cranks and use that? I believe they are neutrally balanced.

Finally, can I continue to use the clutch I had in my 1991 305?

Thanks!

 

this one uses 1 pce pan
http://www.summitracing.com/parts/MOR-38315/

this one require 2 pce pan
http://www.summitracing.com/parts/MOR-38415/



can't you send it back and get right one?
Easier (and cheaper ) for you in the long run.

 

You can't use your old flywheel only because of the crank style. If you had ordered the proper crank type, you could have used your old flywheel because an "internally" balanced 1-piece RMS crank will use a flywheel (or flexplate) with a weight on it, just like your original '91 crank did. The weight replaces a counterweight that was built into the 2-piece RMS cranks, external to the RMS.

It's too bad so much confusion exists over this, but, that's the way it is.

You can use a flywheel for the '83-'85 3rd gen V8 application.

As long as the flywheel you get uses a stock 3rd gen V8 style clutch, yes.

Personally, I would try to get the proper rotating assembly. I don't know anyone personally who has used one of those adapters, but I do know that the 2-piece RMS is inferior in every way to the 1-piece design.

 

Thanks for the help guys.

This is definitely confusing for a first time engine builder, but I think I'm understanding now. I'm also discussing this with Eagle. Let me know if I've got this right:

All assemblies that are balanced for 1 piece rear main seals will be listed as "external balance" because the flywheel weight is always needed due to the design of the crank. Any internal balance assemblies (including the one I got) are meant for 2 piece rear main seals where it was possible to completely balance the crank without help from the flywheel and harmonic balancer.

I returned the wrong assembly today. My only question is why they include a harmonic balancer with every assembly, since a stock set up uses a neutral one? Is it just for convenience, or do they perform additional balancing on it? I already have a nice neutral weight balancer.

In addition, should you always check bearing clearances with plastigauge, even though all parts are brand new? I certainly see the need for doing this if your old crank has been grinded, but what about when its all new?