Thread: I broke a main cap. Please advise

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Well----if the crank is all you have in the motor , take it out and fit another cap---you can fit one with a dial guage by taking vertical measurement and then diangular to see if the off set is equal--you will need one that is equal side to side and if its bigger top to bottom you can cut it down until you get it to specs =====or

Cut them all and line bore/hone it ( which would be what I would do to fix it, however if I was in the middle of no where and engine was together otherwise and in the vehicle---

Originally Posted by jerry clayton

Well----if the crank is all you have in the motor , take it out and fit another cap---you can fit one with a dial guage by taking vertical measurement and then diangular to see if the off set is equal--you will need one that is equal side to side and if its bigger top to bottom you can cut it down until you get it to specs =====or ---

yep i done that if you have alot of caps you can get lucky GM was never that great on hitting dead center on the caps but i have bump them side by side when i have line bore them. with used steel cap or making a 2 bolt to a 4 bolt with gm used caps i bump them by welding the side face. then side face the cap in the cap cutter till it on center or close . i had a merlin a guy soild me with the wrong main cap # 3 bump it over got it on center but was tall by a 001.5 trim it in the sunnen cap cutter then lap it to .0001 call it good .no line bore

always have it line bored.ialways have it done on any engine i rebuild.

Originally Posted by hotrodstude

always have it line bored.i always have it done on any engine i rebuild.

yep i have as well many times. and made rear caps drill for oil pump dowel pins thrust rear seal etc. but if you can hold it under 0002. why? i done it many ways line bore will not make right or better . if the guy with the line bore can not hold it to a size . even so you may not see very many that can or will hold size under 0001 or even 0002 .just trying to tell him how it can be done... maybe over some heads ?? done it just like jerry said line bore will not help much if the caps do not fit off the bat. a line bore will not make the caps fit side to side and make the rester fit someone still has to do that

OH thats .0002 to .0001 not .002 to 001 you get them that close you do not need a line bore you will be lucky if your bearings hold size thru the set under 0002