Factory Five Racing Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter #1
Can my 1968 428 Police Interceptor block 4.17" be bored take NOS original bore 427 4.23 stroker pistons? My block has the extra webbing main with the stick weld "C", but are the cylinders thick enough? Did different castings have thicker cylinders? What 390 blocks can be bored to 428?
 

·
Official OLD GUY
Joined
·
3,813 Posts
Big Block ?

NO . . a 428 can NOT be bored out to accept 427 pistons dirrectly. You would have to way over bore it and then sleeve it back to 427 specs. 427's are 4.230 bore x 3.780 stroke.

390 blocks are not a good canidates for over boring either. Starting with a fresh block at 4.050, you would need to take it out to 4.130 for it to be a 428 . . . that's .080 over. Most 390 blocks I've worked with aren't much good after .060 max.

At 4.170, it sounds like you 428 block has already seen a boring bar . . . it's .040 over now.

If your block is in good shape and you want a little more "spin" out of it, get a 427 or 390 crank and make it a 406 . . . a very potent engine back in the 60's . . . the "little brother" of the 427.

Doc :beerchug:



You would be better
 

·
Registered
Joined
·
46 Posts
"More spin"? A 428 is already oversquare and can handle RPMs. He's got a 4.17" bore and just 3.98 stroke. The important part is valvetrain for spinning it up.
 

·
Registered
Joined
·
5,902 Posts
1 - 4 of 4 Posts
Top