Thread: 402 bore over

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I was wondering can a two bolt main 402 BBC be bored out to a finished bore of 4.250" to create a 427. I believe the factory bore is 4.125". I know big blocks have thick cylinder walls. It would be a .0625" take off the cylinder wall on each side. I just wanna double check and get second opinions.

No no no no

I did it once,In a pinch. Alky circle track motor. It lasted almost a season before it cracked a cylinder wall.

the old 369 block s from 65 to 67 you could bore them out to a 427 or 454 4.250 and some say 125 on top of that for a 4.375 bore .but not all of them and the 402 block you would be on thin ice

Hey Pat,was the 402 a truck motor or something ? I know when I did it it was racing season and it was all I could find in a hurry. Never could figure out what they used it in. Or was it simply what they called the 400 big block ?

does anyone have a 454 block they wanna sell reasonbly priced..?