All four of my pistons have a wear groove about 1/8" wide on the top. Its only on one side of the piston Anybody know why? THANKS

Fit to tight.

Hitting the head.?

Tight fit but how are the cyls? Are they scored all the way down or do you have slight tapers causing wear in one spot on them?

The piston is hottest at the top. Kohnke is right, not enough clearance.

Those look remarkably like 292 Ford pistons and the edges of piston heads project higher into the combustion chamber. I expect the engine is bored oversize and the pistons are scraping on the inside of the head. Looking at the head you should clearly see where they have a clearance problem. A bit of work with a die grinder and all will be well.

Photo of other side of same piston. There is no evidence of any piston hitting the head. Piston measures 3.800 at bottom skirt 3.797 at bottom ring. 3.768 at top of piston with micrometer resting on top ring at notch, 3.779 opposite the notch mike resting on top ring. Over height of piston is 3.382

only one of the cylinder walls has some minor scratches

The ECZ stamping says their not T pistons and it looks like the distance from top ring to top of piston is too high, ergo they are touching the edge of the head, Don.

I have the same problem. This is what I think it is. The top of the piston is higher than the top of the block when it is all the way up. The engine is .060 oversize. One of the head bolt holes been replaced with a helicoil. I replaced the pistons and the new ones do the same thing. I think the helicoil is off center causing the head to slide slightly forward so that all of the pistons hit the head at the back side. This could be verified by checking the head to see if you can see any evidence of the piston hitting the head. If so the head could be ground slightly at each place where the piston hits the head. other possible causes would be bent rods. It seems unlikely, however that each rod would be bent the same way. If only one or two were scored, I would lean toward checking the rods. If the rods were bent, you would have corresponding wear on the lower skirt of the piston at the opposite the wear on the top of the piston.
Norm

Cleaned the head and there is evidence of the piston hitting it. It's about 1/4" into the head on the curve of the combustion chamber. I think you guys are right they are the wrong pistons. The engine did sound ok for me and I found this while removing engine for transmission work. Might as well check EVERYTHING while its out of the car.

Norm,

ECZ (292) pistons work just fine if the clearance issue is cleared up. I don't happen to use them but have a friend who swears by them. If they are otherwise fine, which seems to be the case, I'd open the head just a bit and stick with them. Then again I kind of go with the "if it ain't broke don't fix it" approach.

Your car, your money.

Walt

I am going to guess that you have not owned this engine since it was fresh built? Quite possibly the original owner had a problem with piston to head or gasket contact and corrected the problem by either shifting the head slightly on the bolts as he tightened the bolts are changed to a different cylinder head or? No reason for him to do anything to the pistons as he had the problem fixed. I would certainly continue to use these pistons as they way better than the typical repo piston you buy today assuming they still fit the cylinders reasonably

Les, you are right, I bought the car after this work was done. Can I grind a little in the head for clearance AND maybe file the piston edge? I would weigh the pistons so they are a matched set if filing is ok.