MrGokster

Today I talked to my machinest. He said the the clearance between the new crankshaft and new bearings is 0.003 inch. It must be 0.0026. So 0.0004 inch out. If I use high volume oil pump it will be ok. What are your comments, guys? Do I change my bearing or go with melling 340. (I already bought it)
thanks.

dukedkt442

Crank is worn? Going that far into it, I'd be doing it right with new bearings and new crank to get proper clearance. You make consider milling the crank and going with oversized bearings.

MrGokster

The crankshaft is brand new. My clearance is more than spec (0.0026). Milling brand new crankshaft is gonna give me bigger clearance than 0.0030, right? Undersized bearing inner diameter is smaller which will give me closer clearance to 0.0026 or less than this. So would this bearing below be right for the job?
https://www.summitracing.com/parts/kgb-mb5280xpstdx/?tab=Overview
btw the block is 5.4l windsor.

qdeezie

I would have him mic the crank to see if it is out of spec. If it isn't, then you will have to get a different set of bearings.

Screwed05

Is that checked at only 1 bearing, or an average of all? It's rare that every bearing is 0.0030. I have always had to measure and adjust the placement of each bearing to get them all as even as possible.

You can use a little thicker oil like 5w-30 vs 5w-20 that's the reason they say it must be 0.0026 is for oil viscosity. Just my 2 cents. I'd run it, but I also assemble my engines and would know how I got those numbers.

MrGokster

I dont know if each bearing is 0.0030 or not. The crank and bearings are new. They havent been machined. But the main bores were machined. One of the bores were 0.0005 out. They said they fixed that. After that I ordered standart main bearings and they checked the clearance. Now its 0.0030. I think I should go and talk to them tomorrow. I dont wanna mill my forged crank. Thanks to everyone who has made comments.

dukedkt442

Sorry missed the part of the crankshaft being new. As others said, find out if it is a single bearing or average of all. Was measurement taken at a single location at one journal, checking for out-of-round condition?

It sounds like they line-honed the bores, which would allow the bearings to sit slightly farther away from the crank. Enough to make a difference? It's your call if you want to find out. Perhaps block bored slightly more for slightly larger bearings (larger OD, but correct ID?)

MrGokster

Thats right. They line-bored the block. If it was checked on a single bearing what would be the next step? Is it good to go or buy new tighter ID bearings?

dukedkt442

If it's just the one, I'd probably go with it, but if it is all, you'll want new bearings.

Usually there is a range of acceptable tolerances, not a specific value, so I'm assuming you are outside that range?

MrGokster

They said they checked all bearings they are like 0.003. They will check with Manley if I need new bearings. They also said 0.0004 out of tolarance wouldn't hurt.