Piston clearance for 1917 Ford

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Model T Ford Forum: Forum 2012: Piston clearance for 1917 Ford
Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Diederich on Tuesday, October 02, 2012 - 05:18 pm:

I removed the head to decarbon the pistons and then I checked the piston movement I can move the pistons almost a sixtenth of an inch in both forward, backwords and left and right. To my way of thinking this too much. I did the test with a cold engine. The engine has alum pistons so maybe they need more clearance?
Bob D


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Gould on Tuesday, October 02, 2012 - 05:57 pm:

Personally I would ask myself if I am having problems with the engine, eg smoking, slapping sounds etc. If the answer is no, then I'd leave well enough alone. One of my favorite expressions comes to mind. If it ain't broke, don't fix it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Walker, NW AR on Tuesday, October 02, 2012 - 07:06 pm:

Bob -- You are right, that is too much slop. I agree with Richard that "if it ain't broke don't fix it," but it's borderline broke already. If you don't have symptoms of that, you will very soon. You can button it up and drive it a little while longer if you like, but you might as well plan on boring it and fitting larger pistons/rings pretty soon.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Scott Owens on Tuesday, October 02, 2012 - 07:08 pm:

Bob, Pistons are checked at the bottom of the skirt. They can move around at the top. See if you can get a brass feeler gauge in from the bottom. Scott


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry Ostbye on Tuesday, October 02, 2012 - 07:15 pm:

Robert is correct, The measurement is taken at the skirt not the top. Pistons are tapered because the top gets hotter and expands MUCH further. The clearance at the bottom is more like .005 to .008 or more. If it doesn't knock or smoke bad leave it alone. If you are still worried take the inspection pan off and measure with a feeler gauge from the bottom but still make sure the piston is not rocked in the bore.


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