Picking a 205 block tomorrow but it doesnt have any maincaps, is it ok to use them from another engine ?? mates got a set from a block that was cracked in his garage.

 

no... maincaps are machined (line-bored) with the block... so fitting caps from another block won't align with the block properly
a block without the original caps is essentially scrap
Potentially you could get it re-machined with the new caps, and use ovesize bearing shells (assuming they are available??) but the cost will not be inconsiderable, I'd imagine better to find a block with caps..

 

agree with rich on that .. no matter how cheap it is without

 

Oh well, at least it comes with a new oil pump so not a total loss.

How much of a variation can there be between different blocks ? does the bearing not take up the difference anyway, every set of shells are the same out the packet so it cant be that much of a difference can it ??

How much do you reckon for oversize bearings though ?, machine work I get done very cheap

 

DAVE ,NOT REALY THE THING TO DO BUT I CAN GET IT LINE BORED /CHECKED FOR YOU IF YOU LIKE

 

the caps need to be precisely aligned with the block to form a perfect circle to house the bearing shells. if they are not machned with the block they simply will not be close enough, the smallest error will be a significant problem.. chances are you will find that the crank won't even turn by hand.

 

Cheers Alistair you know where to get bearings for it ?

 

I get it now Rich just couldnt get my head round there how there could be any differences earlier

 

you carnt line bore a block with all caps missing you need to pick up on at least 2 main caps before it can be line bored
and what does over size bearing got to do with line boring thats to do with having the crank ground

 

Brom, in the terms I was using "oversize" implies external diameter increase to accomodate increased housing size (if it has been line bored), "undersize" relates to crank journal grind size reduction. I'm not suggesting bearings are neccessarily available with an oversize OD in this case, but I have seen them for other applications.

 

you must line bore blocks diffent to the way we do it then
lol
we machine a very small about off the cap mounting surface and the block where they bolt together then re line bore the hole again
thus using standard size bearings

 

what are end caps?

 

No you dont do that.

I reguarly have engines line bored, you skim the caps off first, then line bore it after, which means that the hole is still the same size.