360 main cap bearings

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70wayfarer

70wayfarer

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ok, is there such a thing as a bearing for over sized main bores. the shop i used sent my block out for line boring/honing the new main caps. after initial start i cut the filter and found some debris. pulled motor and found the main bearings had a unusual ware to them. the builder measured the bores and found them tapered and oversize.
my question is, to save my block is there a bearing oversize available on the OD.
cheers
 
How much oversize. Tell them to rehone the block. I am going through this right now as well.
 
70wayfarer said:
but wouldn't you still need a bearing with a larger OD. from what the builder told me it is not a lot.
Click to expand...

No, they remove the caps, then mill the mating surfaces of the caps and block...

Then resize the bore to the stock dimensions...

There must be a slight interference with the bearing shell and the nest so there is proper bearing "crush" which helps hold it in place...

If you overbore them, then you don't get the proper bearing crush....

by milling the faces, then they can bring it back to size without having to go larger...
 
krazykuda said:
No, they remove the caps, then mill the mating surfaces of the caps and block...

Then resize the bore to the stock dimensions...

There must be a slight interference with the bearing shell and the nest so there is proper bearing "crush" which helps hold it in place...

If you overbore them, then you don't get the proper bearing crush....

by milling the faces, then they can bring it back to size without having to go larger...
Click to expand...

that makes sense, taking material off the caps and block registers. hopefully that will save my block and caps.
 
This is standard rebuild stuff. Grind cap mating surface and hone back to size. My machinist got the bores slightly too big and I won,t assemble it for fear of inadequate bearing crush( read spun bearings) and I am having him redo the align hone.
 
The taper would be even more of a concern to me.
(if there actually is taper) and if there is I wouldn't let that machinist sharpen my pencil after that.
 
TrailBeast said:
The taper would be even more of a concern to me.
(if there actually is taper) and if there is I wouldn't let that machinist sharpen my pencil after that.
Click to expand...

Well he is a machinist that I have used for more than 25 years. The main problem is his book that he uses for various engine rebuilds gives him a bore od that is on the big side of the tolerance already and then he was a few tenths over that and by my measurement the number one main is .001 bigger than the other four. Anybody can have a bad day and he had always done good work in the past. Luckily this is an operation that can be fixed. Combine with a clevite H bearing that give more clearance than a stock bearing and my clearances were coming in at .004. This is why I build my own motor.
I trust no one.
 

Duane said:
Well he is a machinist that I have used for more than 25 years. The main problem is his book that he uses for various engine rebuilds gives him a bore od that is on the big side of the tolerance already and then he was a few tenths over that and by my measurement the number one main is .001 bigger than the other four. Anybody can have a bad day and he had always done good work in the past. Luckily this is an operation that can be fixed. Combine with a clevite H bearing that give more clearance than a stock bearing and my clearances were coming in at .004. This is why I build my own motor.
I trust no one.
Click to expand...

Oh, well if it was just an honest mistake and a good machinist he'll fix it for you for free then. :D
 
the engine shop i used at the time didn't send it to the guys i wanted them to for align boring. to add insult to injury the shop didn't even check the work when it came back. needless to say i have changed shops.
 
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