Quote:
Originally Posted by Dick Boneske
I've got a '04 421 code 45B, the high HP Tripower version. The block is straight across as I thought all 421's were until this thread. My two '68 428's do have the wave in the casting in the area discussed above. Pictures attached.
One of these days, I need to figure out what to do with the 421. It is a short block assy. with valve eyebrows for later model heads. As you can see, it is bored to 4.185" from the original 4.093".. That's about .092" over standard. Is that OK with a '64 421?.
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I've got a '65 or '66 421 block that is .060 over and I'm going to take it to .090. I've had it sonic checked and it will be ok. So your '64 may be ok at .090 over but I'd have it sonic checked if it were me.