4AGE main bearing caps

[Vertigo]

how hard are these supposed to be to put in place? they are giving quite a bit of resistance, like they are just a tad too wide. are there any differences in the main caps in the 4AGE family?

[thegreatestben]

You need to use the original caps from the block as the two are bored as a pair. If you use the caps from a different block you will only have problems.

[Vertigo]

shit.. one of those things i really would have liked to have known beforehand! has anyone built with caps from another block before? what were the results?

[Burning Angel]

you can do it.... but you will need to get the block line bored with the new caps. this may require oversize bearings but im not sure on that

[evil_si]

when blocks are machined from factory they are line bored with a specific set of main caps.
they must be assembled with the original caps in the correct order, with the correct rotation, usually an arrow pointing to the front,

main caps are a tight fit in the block, usually have to gently tap them in with a soft hammer, if they are loose they can pose problems as with being to tight they fret and damage the mating surfaces.

others may fit, alignment and clearance may be wrong, a machinist will be able to check the tunnel alignment generally they require the bare block

that said conrods have matched caps as well. as do cam caps,
cylinder heads are also 'line bored' with the cam caps in place

mixing and matching is a bit of a no no