deadkelly

i just bought some Arias forged 12.5:1 dome top pistons to suit std 383 4.250 bore . now the pistons measure 4.244 that is .006" clearance for a std bore . I'm sure there made to go straight into a std bore with no problems . but .006" seems like a hell of allot to me & the guy doing my re sleeving / bore & honing . he usually gives forged wiseco pistons .0038-.0042 depending on application , but i do understand that the heaver old pistons are probably made of a older type of alloy not used today ( pistons were made in 1972 ) what should i do i have rang around & got very different answers of what 2 do . logical step would be go to std 4.250 but since I'm starting from scratch i can have what ever will work best , & because this is a street strip 550 + hp motor potentially it could heat up allot in our very hot & humid BRISBANE AUSTRALIA especially if i get stuck in road works or traffic mmmm . WHAT 2 DO ????????? any suggestions or dose anybody know ?????? OK thanks .

theomahamoparguy

probably correct or close. Might go 1/2 thou tighter.
dome pistons expand more {think hemi }(65 race hemi had a clearance of .0125)!!
and technology has come a long way. You definitley dont want to "scuff" a piston by it being too tight. the old forged pistons didnt have the technology and they really liked to rev those 383's back then so they set them up loose. BTW, the original max wedge race engine had a clearance of .0095 from the factory. The regular 426 wedge {non race engine} had a clearance of .0005-.0015 with the CAST pistons. The 426 wedge had the same bore diameter as a 383. So the .006 clearance doesn't seem too crazy in comparison. Just my .02.

deadkelly

thanks allot mate , mmm yeah my Lil 383 is gonna be revving till the lifters can't cope then I'll set the rev limiter about 150 rpm bellow that point for now anyway.