I am wondering if anyone can tell me why Ford changed the shape of their pistons over the years. I know the early engines had flat pistons and then they changed them to a slight bevel, only to change them again to a bigger bevel. Any info would be greatly appreciated.
Chris, Flame propagation.
What year had flat pistons?
Then Model A's and flathead V8's had flat tops. I think it was that way until Ford introduced its first high compression engine running on high test gas.
Up till about 1914 the pistons were flat topped.
I'd have to say that I have never come across flat top pistons, early parts books show bevel, the only difference I can see is very early had the 3 rings at the top and by mid teens one was put down the bottom and 2 still up the top.
I see that the encyclopedia says that the water pump model of 08/9 had flat top pistons.
One of the two engines I am considering using in the '15 runabout has flat-top pistons in it. It is a late '15 engine. I haven't looked at them closely enough to compare the compression. I certainly do not want lower compression. Guess I need to start working on it and check it out closer.
Sharp edges are bad in a combustion chamber - they get hot. Since the pistons protrudes up into the combustion chamber like in few other engines the T engine is a bit odd. Restorers back in the 50's or 60's took whatever pistons they could find that fit - usually flat topped like most pistons not for T's. Maybe a light beveling of the piston tops while the head is off would help?
I would try it, very little sanding like making a small radius would minimize heat concentration at the edge, I think?
I've got one like that Roger, the last T I bought, a re-build with flat top pistons some time in it's life, on the hills it was hopeless, fitted a Z head on it which bumped the compression up to 70psi, now runs as good as a standard T.
So the pistons didn't protrude over the deck plane at all on your latest, Frank?
Ok, when I think of it, most flat topped pistons has the rings near the top, so it wouldn't be possible to let it go much over the deck even if it was tall enough over the piston pin.
That's right Roger, deck height.