Problem with 393 crank! HELP
 

I purchased a 3.85" stroke crank for 351W off of ebay from RACEPARTS. It is suppose to use stock 351W rods and 302 pistons to make a 393. Well the counter throws on the crank hit the pistons and won't let it turn. Has anyone ran into this before? If so, how do I fix it? Thanks.

You can't add over 3 tenths of an inch to the stroke of a crank and not change something. Are you sure they said you could use both stock rods and stock pistons?

edit: I stand corrected, i ran that combo through a compression formula and it appears to be reasonable. As for the interference between the piston skirt and the crank counter weights, you'd be better off contacting the guy you bought it from, they must have something in mind ?

first off lets get the basic's and asume that the crank is ok.

where did you get the pistons from ? did you already have them or where did you by them from somewhere else ?

This is in what year 351 block ?

you can get a strocker crank that workswith 351 rods and 302 pistons the 302 pistons have smaller hight and ring package thats what makes it work.?

if everything is as it should be and there still is interference get the dremel out for all 8 pistons but that would be a last resorte.

It is suppose to use stock length 351w rods and 302 pistons!

yes but if for some reason you got 351 pistons instead of 302 they will interfer like you said. you cant just remove the 351 crank and put the stroker crank in. also they may have sent you a 408 crank whick uses diffrent rods and pistons what part # does yours have ?

302 pistons are smaller from top to bottom what type of pistons do you have and where did you get them ?

I've done a few 393 type cranks and havent had to many issues except rod size a friend ardered a for rod size and got a chevy sized rod mains.

how bad do they interfer ?

Last night when i answered this thread, all my feeble brain saw was stroker crank, stock rods, stock pistons ... the 302 part of the piston equation didn't even register. I couldn't figure out how the guy was telling you that you could throw in a stroker crank without changing rods or pistons and everything would fit ???? duhhhh :p
You had me scratchin my head for an hour last night !!
At least it makes a little sense now .... if you have 351 pistons with stock rods and a 3.85" stroke, the pistons will be sticking out the top of the block, so that should be easy to check. Maybe you have aftermarket pistons and the skirt design is a bit different (longer) ? If thats the case i'm with BilLster, you could probably do some notching with a dremel, then get everything rebalanced ... if the interference is substantial, then i'd find out whats going on before i cut anything.
note to self: Don't try to figure out technical problems late at night liquored up.
:rolleyes: