LA 360 - 0.030" Undersize Main Bearing Clearance Questions

Desoto291hemi said
I’m confused a little .
Your first post stated it was basically a street engine,,,,,maybe an occasional drag race .
Would not see above 6000 RPM,,,,,but the crank doesn’t have the “ clearance necessary for running it hard ? “
If it’s a good crank,,,,,any professional guy that polishes crankshafts can take anywhere from .0003 to .001 off of it easily .
Yes,,,,,there are good crank men out there,,,,,not cheap,,,,,but the right operator with the velvet touch can get that done for you .

Or,,,,you can buy a new crank,,,,,but beware,,,,,all new cranks are not created equal .
I’ve seen many of them not perfect as well .

Good luck .

Tommy

Thanks for the response, Tommy. You're right, most of its time will be spent on the street, but it will also see the track. For the street, it seems like the current clearances are probably fine. You're also right that I probably shouldn't definitively say that it doesn't have enough clearance for something that is going to see the track. Based on most of the other feedback I've gotten, it's a gamble though. I mean, it might be fine. All of the major bearing manufacturers seem to recommend 0.001" for every inch of shaft diameter. That means I should be somewhere in the 0.0028" neighborhood. I'm no where close to that. Then again, the 318 that is getting replaced had a stock short block that probably has similarly tight clearances. I shifted that thing at 6000 RPM and never had an issue, but it was only at the track a handful of times. Just trying to make sure this thing gets done "right", I guess.

You're also right about new crankshafts not being perfect either. Idk, there is risk no matter which direction I go. Seems like a different crank has the highest probability of success. I'm also working with limited time. I need this thing ready to go by the first week in October.

I still haven't circled back up with my machinist. Having a hard time getting a hold of anyone over there today.