Piston Bevel

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Model T Ford Forum: Forum 2015: Piston Bevel
Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Brainard on Thursday, August 20, 2015 - 09:11 pm:

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.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Owens on Thursday, August 20, 2015 - 10:39 pm:

Chris, Flame propagation.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Thursday, August 20, 2015 - 11:45 pm:

What year had flat pistons?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry Woods, Richmond, Texas on Friday, August 21, 2015 - 12:08 am:

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.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Friday, August 21, 2015 - 12:29 am:

Up till about 1914 the pistons were flat topped.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Friday, August 21, 2015 - 01:08 am:

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.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Friday, August 21, 2015 - 02:01 am:

I see that the encyclopedia says that the water pump model of 08/9 had flat top pistons.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wayne Sheldon, Grass Valley, CA on Friday, August 21, 2015 - 05:14 am:

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.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Friday, August 21, 2015 - 05:23 am:

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?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Friday, August 21, 2015 - 06:15 am:

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.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Friday, August 21, 2015 - 06:37 am:

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.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Friday, August 21, 2015 - 06:54 am:

That's right Roger, deck height.


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