Thread: 402 BBC build

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Originally Posted by chevybuilder

Thanks Pat for the response.

I checked the pistons, at least a few of them until I found they had 0.005" clearances from the ideal bore. this I think is too much. I also checked the rod bearing roundness until I found one that was 0.0025 out of round. From these results I think I should go ahead with boring the block to 0.060", new pistons, and unfortunately new rods. I haven't check the crank yet but after finding the condition of the rods and inspection on the rod bearings I think the crank should be turned. This means it would be 0.020" undersize now. From what I have read this is ok.

I could pickup a used engine and salvage parts to save $ but I don't want to get into it and find similar results. Thought I better go new.

Anyone have any advise they would like to share about these results?

bearings are not round from 12:00 to 6:00 is where they will have the least size 9:00to 3:00 parting line they will open up about .002 more . you need to check housing bores for out of round mains and rods .most all the time mains are ok .rods can go out of round and rod s should be rebuilt with new bolts or new rods like scat I beams .you need to check the crank for shaft size and how much they vary this is all stuff i do every day if cast pistons .005 to wall is to much . for size on rods and mains housing bores i like them all to at small spec no more then .0002 from target size