I was wondering if it was possible to just drop a 427 crankshaft into a 402 block, and then run stock 427 pistons. Seeing how they share the same bore size, the only difference could be the deck height (right?). I want to build a motor for a friend of mine, but want to leave the current motor in the car while I am building it. The previous owner says that it is a 427, but after running the casting numbers it came up as a 402 block. Thanks.

 

The stock 427 bore is 4.250".

The stock 402 big block bore is 4.126".

For all practical purposes (a machine shop can easily take care of the minor balance issues), the cranks are the same in the two engines, as are the rods.

AND it is POSSIBLE (must be checked to be sure) to overbore the 402 block to 427 bore. Been there, done that.

AGAIN, must be checked before overboring a 402.

jms

 

As soon as I read your reply, I realized that i had my whole post *** backwards. But you did manage to answer my question. I was wondering if the 402 can be bored out that much... Too many numbers in my head. THanks for the quick reply.