general23cmp

iTrader: (1)

I am looking at purchasing a block. The owner says it has been line honed and measured 0.0005" oversize. Is that acceptable, does it require special bearings, etc.? I did a search for main bearings, and the only things I found were in reference to the crankshaft (undersized bearings).

KCS

iTrader: (20)

The main housing bores are supposed to be 2.7509"-2.7515". If the mains are .0005" over the low (2.7514"), you're okay. However, if the mains are .0005" over the high (2.7520"), that's not okay.

The diameter of the housing bores is what keeps the bearings in place. I don't know if .0005" is going to cause a bearing to spin, but I wouldn't want to test that.

general23cmp

iTrader: (1)

Thanks.

That seems like a very tight window to hit, especially with so many people having their block line honed, not to have options (larger bearings) if the mains were 0.0005" too large.

KCS

iTrader: (20)

The difficult part is getting all of the bores within spec. When the mandrel is honing back and forth through the bores, some of them will wear at different rates. Everyone has their tricks to get them all the same.

If the machinist goes over too much, he'll just cut the cap where it meets the block and the bore is undersized again.

general23cmp

iTrader: (1)

Are you sure about that range above? I have a book that says 2.750-2.751". The line hone of the block in question is 2.7515".

KCS

iTrader: (20)

Positive. That spec came from a 2005 Clevite Bearing catalog, pg 364. You can find the catalog online, and it will say the same thing.

helicoil

iTrader: (104)

I have seen both specs. published, in fact, I am looking at a 00 service manual right now and it states 2.750"-2.751" or (69.871-69.889mm). So it is a bit confusing.

general23cmp

iTrader: (1)

Probably best to use the bearing manufacturer's numbers since their part must fit in the bore...

KCS

iTrader: (20)

It's the same spec, but the Clevite's is more accurate to the .0001"...2.7509"-2.7515". I think the GM service manual is more for a rebuilder type shop. They do things differently than a performance engine shop.

If the housing bores are 2.7515", according to Clevite, you're golden. Put that thing together!