Engine Rebuilding

[Stuart Adams]

When rebuilding a 427 is 65 over rebore too much? Usually I was told 60 is max, any thoughts?

[jeff morocco]

i went .125 over in one of my race motors.....the only problem with that is if you have something go wrong....its junk. no room to fix!!!

[427king]

060 is the max if you are building a newer motor. The early vintage 427 blocks will take that bore size with no issues at all

[ANDY M]

My motor is .100 over. Runs fine with a 160 thermostat. Like Jeff said, drive careful. The powertrain warranty is in your wallet. http://www.yenko.net/ubbthreads/images/graemlins/naughty.gif

[SMGCO]

[ QUOTE ]
When rebuilding a 427 is 65 over rebore too much? Usually I was told 60 is max, any thoughts?

[/ QUOTE ]

You need to sonic test the block to determine the actual remaining cylinder wall thickness then you can make the call.

[Chevy454]

A sonic test would be good insurance, but if it's an older/original 427 block then you should be golden...I've heard several folks going to .100 or better on the older stuff...but, if it's gonna be tight, then sleeve it and you'll be better off for it all around!

[COPO427]

You could sleeve it if the block is important enough to keep for #'s sake.

[Stuart Adams]

That's the kicker, the motor and the car are restored fresh.

[indyjps]

i'd bore it and drive gently, if you want to run it hard swap a new block in and keep the orig block on the stand.