Just pulled the head from my 1919 Touring. If the engine has been bored sometime in its past 93yrs would the tops of the piston be marked as such ? These are cast iron and have no markings..standard bore ?
throw a caliper on your bore and sweep it back and forth and the largest reading will be pretty darn close.
yes most cast iron pistons ive seen are marked with an over size. have you cleaned the tops thoroughly? it could be easy to miss the marking.
Yeap...cleaned them but couldn't see anything but 2 little punch marks.
the punch marks, from what I was told are the weights that the piston and rod weighs, there was four weight groups, I first thought they where stamped 1-4 for the cylinders they where in but the punches where the same on every piston?
Yes..these are all the same
Joe Bell covered it. Weight groups for rough balance from the factory.
And if you really look for it, the original Ford iron pistons are always stamped 'Standard' to indicate factory bore size.
Many times you can't see the stamping, old crust of carbon, or gouges from years of chisels scrapping off carbon
Highlighted the STANDARD marking with chalk.
And Ford oversize iron pistons are likewise stamped, but no dots, as these later pistons were placed in the motor outside the factory, so no factory assembly weight dots.
So what i may have are standard Ford pistons...WOW ! after 93 yrs you would think it would have been bord at least once ! Pulled one of the rod caps tonight...babbit looks good but no brass shims. I've got a long way to go !
I don't know about Eastern states, but in Califunny, I have owned nearly two dozen original T blocks over the past forty years. Only two had ever been bored oversize, and only two others so far have been worn enough to require being bored out.
Drive carefully, and do enjoy the holidays! W2
I noticed in one of Dan"s photos that one piston was stamped .025 OS. The motor in my grandfather's 27 coupe had .031 OS pistons and we had to rebore to .040. Does anyone know how many factory OS pistons Ford made. I know they made .040 OS, also. Why would they make a non increment of 5 or 10 piston (.031)?
Terry, that's old skool stuff, if an engine had one crook bore that's what was fixed, cleaned up the pot and fit a matching slug to it, some times even turning the piston to fit. Same as bearing journals, only grind the ones that are out of spec.
It would seem that Ford supplied replacement pistons in fractional measurements as a .031 oversize piston would be 1/32 OS.
Thanks Wayne...if I'm lucky I won't need to bore this block.
Actually that is 0.0025 oversize. Legend has it a lot of oversizes were available.