Thread: 454 crank

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How far can you machine down(undersize) a crank shaft? Is .030 to much? What are some of the problems that coma with this if any? The crank is a stock cast.

i have run them at 030/030 and steel at 040/030 some guys run a 2.100 rod pin thats is under 100 .i do not see much in to this if just a mild 454 a 030/030 crank is better then no crank but if it has been welded on? then just buy a scat iron replacement crank

Originally Posted by pat mccarthy

i have run them at 030/030 and steel at 040/030 some guys run a 2.100 rod pin thats is under 100 .i do not see much in to this if just a mild 454 a 030/030 crank is better then no crank but if it has been welded on? then just buy a scat iron replacement crank

I agree with pat. How far a crank is turned is less important than how well it is turned. A .010" grind with poor fillets is less desirable than a .030" with well ground fillets. Also, make sure the thrust surface is in good shape. Some bearing companies make .010" or .020" oversize (length) thrust bearings to allow that area to be machined.

tom

The shop that does the crank work for me ask that we go 020 over max on are race engines . But he will turn a crank 030 for a street only engine . Todays cranks are cheaper to buy . Look at buying a new one before you spend the money turning down yours 030 . If you have to use yours buy a real good set of bearings .

i have have seen 030. get run hard if the steel backer of the bearing is thicker then the bearing is not going to get beat out .just more bs like not running over 020. like tom said if it as a good fillet on the radi of the crank them run it.the only thing i will say on the 020. over is you may not find a H bearing bigger then this but if your building a 700+ hp engine you may want to re think the stock gm crank anyways.and the H bearing i would not run on a stock crank anyways .i am not a big fan of welding on iron and if that was done and is ground to 030 i would not use it .i have used iron cranks re work the oil holes and get all the sharp spots off the then i would shot peen the hell out of them then get them turn .like i said it is not much of a big deal had a 040/030 crank that seen more rpm then alot of drag cars would ever do and sold the bottom end to a hill climber / mud truck still is fine

That the nice thing about a SB Chevy . If you have to cut your cast 3.48 crank more the .010 and dont want to . You can find lots of better cores or buy a new one cheap .