Hot Rods Low flathead compression

Hi all hambers ... after lot of smoke from oil filler tube today I check the compression on my 8ba....all cylinders are around 60 65 psi.... engine around 130 deg...... Time to rebuild the engine I know..... Is 0.125 bore over and 3.75 stroke.... What you suggest for a more bore and a good stroke? Thanks

 

I might try adjusting the valves first.
Secondly, All it may need is rings. Check for excessive taper.

If the block needs to be bored, only bore for the next size rings and pistons.

0.125 seems excessive to me. I have a 8BA 0.040 that cracked a cylinder.
Due to corrosion and casting flaws...the less over bore, the better.

3-3/4 is the stock Ford crank. The 255 Mercuries has a 4" stroke and a Mercury crank was a popular swap. With that said, the stock Ford cranks does fine.

 

Follow F-ONE's advice. Bigger is not always better.

 

There are many flatheads running with .125 overbore. Mine has been running for almost 25 years now.

 

Yes ..i know 0.125 is a bit big bore…...looking on ross pistons i see they have two sizes of bigger pistons….actually i have a 3.313 bore…...ross has 3.342 and big 3.375...…….just i'm looking the best choice...thinking to upgrade with a stroker crank……..F-one is right…..first of all i try adjusting valves….

 

I have a block that failed with a .040 over bore. There's lot of factors some going back to the casting. Any time you bore one of these old engine....be prepared to sleeve.

That would save my block but I have another.