line honing mains, question

**general23cmp** · 01-24-2010, 09:39 AM

I am looking at purchasing a block from a friend. He says the mains have been line honed and are 0.0005" oversize. Will this require a special bearing or standard ones? I have looked online, and the only thing I find in regards to main bearings are referenced to the crank (undersized bearings). Thanks.

**RARON455** · 01-25-2010, 02:50 PM

I am with you, Oversized bearings are always in regards to the crank main and pin diameters. I have never heard of the main bores being oversized, from my understanding when a block is honed they take the caps off, knock a little off the ends,(making it smaller) then hone back to size.

**general23cmp** · 01-25-2010, 03:02 PM

Originally Posted by RARON455

I am with you, Oversized bearings are always in regards to the crank main and pin diameters. I have never heard of the main bores being oversized, from my understanding when a block is honed they take the caps off, knock a little off the ends,(making it smaller) then hone back to size.

That is what they do, but they have to move up slightly into the block in order to remachine that side along with the main caps. If this is done too much, it can casue the timing chain to be a little sloppy. I'm just wondering if 0.0005" is enough to be concerned about spinning a bearing??? Seems like a crazy small amount, but who knows?

**importhater81** · 01-25-2010, 03:29 PM

At .0005 you would still be in the service spec of .001 - .003" with standard bearings.

**general23cmp** · 01-25-2010, 03:33 PM

Originally Posted by importhater81

At .0005 you would still be in the service spec of .001 - .003" with standard bearings.

I am talking about the bore of the mains without bearings right now. The are bored/honed 0.0005" too large.

**JaycenK** · 01-27-2010, 12:42 PM

Originally Posted by general23cmp

I am talking about the bore of the mains without bearings right now. The are bored/honed 0.0005" too large.

You do understand how small that is. you could take more off with sand paper. The bearing has a range and he is saying you are well within it. He said +.001 / +.003. it just didn't look right because of the -

Now are you saying you are .0005 over the range he gave?

**joedude02** · 01-27-2010, 01:22 PM

Originally Posted by importhater81

At .0005 you would still be in the service spec of .001 - .003" with standard bearings.

what he said.

**importhater81** · 01-27-2010, 04:32 PM

What kind of block is it that you have? A few years ago a built a 540ci merlin block and when installing and measuring the crank bearings I found the clearances were to tight requiring the block's mains to be aligned honed to reach proper specs...with standard bearings.Point being 9 out of 10 times after align honing mains and using a crank that has not been ground results in the use of standard bearings. Most crank bearings are offered in standard,.001 undersize for align honed blocks,or .010,.020 undersize for cranks that are ground and polished.If I were you I would install and plastigage the crank with a set of standards,chances are that is what you will be using when all said and done.