Why are my AE piston ring land clearances so large at .006"?

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jimbo

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Why are my used .020" over AE pistons ring land groove clearances so large at .006" on my MK3 ? They are supposed to be at .001" , does that sound right? If so ,wow a big difference. Everything else seems to be worn but OK.
 
That’s between the horizontal surfaces, not the curved inside circumference?
Worn out, I’d say.

Phil Irving gives a maximum of 0.002”.
 
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Why are my used .020" over AE pistons ring land groove clearances so large at .006" on my MK3 ? They are supposed to be at .001" , does that sound right? If so ,wow a big difference. Everything else seems to be worn but OK.

A pair of original 850 AE Hepolites measure a tight 0.003"
 
As stated, the pistons are worn out and need to be replaced.

FWIW, are you sure that they are supposed to be .001"? Sounds awfully tight for a street engine .002-.004" is a typical figure. But, in either case, those pistons are now best used as ashtrays. ;)
 
I have a pair of Hepolites on my shelf and you can MAYBE force in a .002" between the ring and the ring land in some places but not in others (the average is less than .002"). So maybe it depends on the Hepolite piston being measured. The JE pistons definitely measure tighter than that.
 
It’s an area where you can’t safely tolerate wear. I think your pistons with six thou rattle space above the rings are heading for disaster.
 
I replaced pistons on my '72 after maybe 30K miles because the ring lands were worn out. The bore was fine. It wears like cast iron!
 
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