Thread: BBC 402 Main Bearings HELP!

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me and my frend was assembling my bottom end, and we got the crank in and the mains torqued down to spec. The mains were all plasti-gauged at .002 tolerance. Right about where the book says they should be. The crank was ground .010 and real nice and smooth to the touch after it came back from balancing.
We put the pistons in and spun the motor over a bunch of times by hand. All the main and rod bearings were well oiled, and the motor turned very smoothly. after we got dun cheeking how much the pistons where in the hole We pulled off the main caps and yanked the crank back out and this is what we saw.

the block was line honed too

Is this normal? These marks don't seem deep at all. You cant really feel them or snag a fingernail on them. It just looked a little odd. Is this anything to worry about?

i had a LOT of RED assembly lub on it and i tried to cleen it as much as i can it didint look like there was any lint on it

"that cylinder bore looks badly scratched" no it is just the coding for the postons it wiped right off with a rag

with a feeler gage can't get any thing over .008 in there

well on the crank end play did you set the end play. many do no set the main cap ? you could move it but and .008 is fine it looks to me your crank could have some run out did you check is and some hi spots in the bearings or the crank you have hit some spots that are up should be ok .002 is abit tight but will be ok for mild use

it is a 1971 402 and ill be runing a THM350 "what is crank run out"

Originally Posted by BBMonte

it is a 1971 402 and ill be runing a THM350 "what is crank run out"

the crank having some whip (run out )

i don't under stand and is there any way i can titan up crankshaft end play

well the crank having the center line of the mains off this could be check in the block by a dail gage O the gage on the main journal that is with the main caps off and turn the crank and see if it moves the gage off O if it will thats is run out and if it is more than .001 or less then you many move the finsh off bearings

you can cheat it by moving the cap but why .008 is ok ?

what would u think would be max end play and do u think i can just cleen up every thing and just run the barings?

the rods where in the middle of .002-.003 i had to do it like 5 times it was varey hared to stop the crank form spining

yeah i think i am good there i got a "Malling High Volume Oil Pump" i figer if the PSI is too high ill just run liter Whate oil