Grooved main bearings bad for cast cranks?
 

Good morning. A buddy I follow on social media recently put together a full roller 455. He found bearing material in his oil filter and motor is not torn down yet. He mentioned how he may have messed up running the grooves main bearings on a cast crank. As in don’t use em with a cast crank. My machinist mentioned ordering these for my build. What’s your thoughts? If I make 450 hp with my build I’ll be over the moon. But Would be cool if the short block would be good for more since I’m gonna run forged rods and pistons. Any tips on what bearings are STILL good these days. Was thinking clevite77 was the industry standard? Ok. I’m rambling on. Thanks all.

No issue at all running full , partial or no lower groove main bearings in a Pontiac up to atleast 700 HP range. Above 700 HP , one might want to think about it.

Until it’s fully torn down with the Cam out its all just conjecture!

I’ll keep all posted once I know how it went.

Non issue regardless of crank material. However on Cast cranks, I do prefer P series, H series on Forged if using Clevites.

3/4 groove are a nice Main and Rod Journal assurance.

PMD used these .