I can't decide between these bearings for my rods and mains.

TriMetal Main
http://store.summitracing.com/partde...D4663M&FROM=MG
BiMetal Main
http://store.summitracing.com/partde...4663MA&FROM=MG
The tri metal mains say direct replacement and full groove but are supposedly only half grooved. The bimetal mains are 3/4 groove and are listed performance.

TriMetal Rod
http://store.summitracing.com/partde...2555CP&FROM=MG
BiMetal Rod
http://store.summitracing.com/partde...55%2DA&FROM=MG

Both bimetal bearing sets say they have silicon in them and can possibly polish the crankshaft.

Any input for a 383 build?

 

Probably not that much practical difference between them. I used the bimetal in my last build. If nothing else I can feel better about not polluting the environment with lead during their manufacture.

 

My engine now has tri-metal bearings in it on recommendation from my machine shop. I use the Clevite 77 HX series

 

What role does the silicon play in the bimetal bearings? Does it do any good?

 

The bimetal bearings use aluminum alloyed with tin, copper and sometimes silicon for the backings. The silicon is to modify the properties of the aluminum. Probably for wear resistance or some such thing. As a side effect, supposedly it will "polish" the crank.

Trimetal bearings are the traditional babbit over copper/lead/tin/nickel/antimony/arsenic/whatever composition. They have a greater load capacity than bimetal bearings, but they'll flake apart and fail immediately if the block distorts at all. Bimetal bearings don't have this problem, and have better wear characteristics and resistance to seizure.

 

I think I'll try the bi-metal bearings this time. Thanks!

 

I went with Clevite 77 Tri-metal P bearings on both my motors.