Can anyone tell me if Pontiac used basically the same block ? I need to bore mine .030. I can only find pistons that are .060 over. I know that they had a 3 1/4" bore in 1940 and in 1949 it was 3 3/8 . The .060 would be about 3 5/16 (3.310) It sounds like it's OK but before I have it bored I'd like more info.
There has to be someone who has a smaller overbore than that. That sounds like that could make it the last overbore before you would end up sleeving that block.
The inline eight is basically the same block from the 30s through 1954, but there are various upgrades through the years. I'd be very surprised there are no .030 pistons.
I've been all over the internet for two weeks. Someone I called has a lot of different sizes of aluminum coming from Europe in Sept sometime .
If stock bore is 3.250 and the '54 engine is 3.375 if I go to 3.310 why won't it work & still be able bore again. Rustynewyorker says the blocks are basically the same .Must be a lot of straight 8's being rebuilt this year.
I don't know the answer to your specific question, but be wary of the phrase "basically the same ......". Generally, when a manufacturer increases bore size, new casting patterns are made. You can't make a 400 cid Chevvy with a 265 block, boring bar, and new crank.
I understand. That's why i'm asking questions. Mine is 1948. I wondered if they cast the block heavier for 1949 to get 268 cu. in.
Why not sonic test the cyl walls and bore all the way if they will allow? If pin height and other specs allow. You can get whatever size piston you want from the "racing" piston makers. Ben
I found a set of unfinished pistons here in Michigan (Northwestern Auto Parts) and they were able to grind them .030 over so I think I am ready to go. THANK YOU for your input And getting me to at least to think outside the box .
The Jalopy Journal
