I have a 59A Flathead that I'd like to run in a mild hot rod. Needs a full rebuild but spins free. I haven't cracked it open yet, so it'll all hinge on if it's a good block or not. It might become a $300 dollar coffee table if the block is bad. I want to run two two's, stock heads, mild cam, S-10 T5. I'd like to get around 8:1 compression with the OE heads. I've read running more is a waste in a Flathead. Anyone got any suggestions on a parts house that might offer such a piston? Thanks. EDIT: Also my Flathead has a little silver tag (I think it's aluminum) on the top corner of one of the cylinder banks. Don't recall which one off hand. I read once that might be a tag indicating a factory re-man engine. Anybody seen these little tags before?
The stock pistons have as big a dome as will fit in the heads. Flattie CR is determined by the head volume. You can't just plane them either, the clearance is not there.That said, there are higher comp. stock heads out there. I don't have the # at hand, but Ford made some high altitude heads for trucks that were 8:1 and higher.
Ooops! My bad. The EAB heads on my 255 give it 7.6:1 CR, and that's about the highest for stock heads. Can't find the #'s yet for a 59a head.
The good heads for a 59A are "81SB" IIRC. But even in the days when flatheads were still coming in new cars they were rare as hen's teeth. Known as "Denver" heads because as said earlier, they were for high altitude.
The Denver heads are a good choice but even when flatty pieces were plentiful and cheap they were pretty hard to come by and normally held very dear to the seller. Another option and a good head is the canadian head. I can't give you a compression number but they are a sweet head from the factory. You are looking for the smooth head. They can still be had and with the nuber of canadian HAMBers that regularly participate they mey even be found reasonable and shipped south. There are any number of manufacturers that sell higher compression heads for flatties. I am not a big flatty guy any more but there are several on here that are into going fast. Maybe with this little bump they will have a chance to see this. Egg is one manufacturer that comes to mind, I think Wiseco also makes flatty pistons. Either of those will be a little pricey. Anyway I'll PM a link to this for you to Mr Flathead hear in KC. he will have a good answer for you.
59A 77-79 59AB 73.5-75.5 6.75 to 1 81ASB (Good Luck)on 239 engine 60-62, 8 to 1 C7ra Canadian (real, not Weiand cheater) 69.5-70, 6.8 Any serious milling needs careful claying in and most probably re-doming. Finding someone with a decent dome shaped cutter is likely to be a challenge.
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