So me and a fella i work with were chatting one day about flatheads and what not. He said he had a friend that might sell his old flathead that was in a boat he had... Next thing i know im driving to pick it up. The guy said he would sell it to me for 125 bucks. He tells me it was built in the late 60's ran in a home made boat. The story is it was bored 3/8's of an inch over. So its bored stroked, has stainless valves, merc heads. And a buncha other stuff... WELL my question is, Is it even possible to bore a 48 flathead that far over? will it run in a car? Am i going to have heating issues? I'm still wet behind the ears so any help is appreciated!
I don't think you can bore it 3/8 over - one could be bored to 3 3/8 - which is 3/16 over - But you should jump on it - its only $125 go ahead and take the gamble! If it has a Merc crank thats usable you have already come out ahead. If everything else is correct it should be a score.
He probably meant a bore to 3 3/8", which is about the max for these engines. 3/8" over bore would put him through the water jackets, and unless he's running special sleeves, this is not a good thing. Of course, he could be talking about a 3/8" stroke, which you get by re-grinding a late Merc crank and using early full-floating rods. Usually, people like this don't have (or understand) the real story with these engines. Unless there are some external speed goodies, I'd look long and hard at this, even at this price.
Thank you for the info! Looks like ill just pull the heads and see whats up in there. It also came with a edelbrock triple deuce intake and 4 carbs and a bunch of flathead stuff off a boat. Like FEDERAL exhaust manifolds and motor mounts and things of that nature.
so i pulled one of the heads and everything looks good and new! on the top of the pistons are stamped 3 3/8
Before i pulled the head it felt like it had good compression when turning it over with a breaker bar. After talking to the old owner he said it was only ran for a break in period after he got it back from the machine shop! For once i dont feel like i got screwed on a deal
how did the cooling circuit run on the boat? was it to a radiator or did it just pump lake water through the engine?
well it didn't have water pumps i just had pulleys where the water pumps go. So im pretty sure they just scooped water out of the lake. And yeah the exhaust manifolds look to be in great shape, i think they say "federal" on them. Im sure ill put them for sale here soon.
Thats correct!---Back in the "day" late 40's & 50's, all the fast guys were running mostly 3/8X3/8 bored out. The flatty I was running in my '49 tudor was bored to 3/8X3/8, ported & relieved, olds adj. valves, isky cam 3/4 race, Edelbrock aluminum heads, Merc. 4" stroked crank, Offy 2 carb intake manifold with '97's, Mallory dual ignition & headers.---Don
No disrespect, but I think you are a little mixed up. The first part of "3/8 x 3/8" means a Ford 3-3/4 stroke crank is stroked 3/8 more. Commonly done by offset grinding a 4" Merc crank to 4-1/8. So your Merc crank is actually stroked an 1/8th. Then the second "3/8" means the bore was taken to 3-3/8". Or is that what you meant?
http://www.flatheadv8.org/flatratio.htm refer to this web site...excellent source of flathead details.
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