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Discussion Starter #1
Hi. i plan to use these for my D16Y8 buildup. (11.3:1 c.r., .025" head mill, 2- layer OE HG, crower2 cams)
While hoping to get a definite answer whether it was necessary to mod for clearance or not (and due to the mixed answers i got) i eventually decided to DIY the valve reliefs of my pistons.
But whether this decision was made in haste or not, i would only request for people to look at the extent of the work done & tell me if i did them correctly and would be safe to use..
In addition,I will weigh them individually and make sure they weigh as close to each other before i/ or if i use them.






side angle to show new depth of valve reliefs and edges of crown


modded - left ; stock - right


two modded pcs side by side

I apologize to those who have given me advise that it wasnt necessary to do this.
I just cant trust my claying skills and these are just spare pistons as well (like the valves i posted before)
There were just too many different opinions about it (hitting and not hitting) that i kinda got overwhelmed and decided to go for it.

(to eyal951, how i wish i saw your build thread earlier..)
 

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Is that an Alaskian Spitz (sp) in your avatar? My wife had one; it's name was Powder. Anyways, cuz it's a spare it'll not harm anything... But I'd not run anything that important in the motor that I had to "adjust" from factory specs. If it had been a well known fact that this could been done and run well, it'd been a different game. But unless you'd like to be the G' pig on this, feel free!
 

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Discussion Starter #4
Thanks! it's a japanese spitz, name's Sato. Died of pesticide poisoning back 1998.
Anyway, i do intend to balance them, get each one on a digital scale and adjust their weights so they'd be very similar (or close to very similar at least LOL) to each other.
Coz i dont understand when people said the PM6 pistons would hit, then my question is "what did they do to prevent this from happening while still using the pistons?"
Machine shops told me they would adjust the location of the valve reliefs but they charged for an arm & a leg. So i just proceeded to do it myself. (i figured it would end up looking the same anyway)

Keep your opinions coming guys. Please.
 

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the only thing i'd be worried about is that the areas circled below are very thin now:



I'd be worried about the combustion being able to actually bend it or break it. either way, its not good news. I'm not metallurgist, so I don't know for sure, but seems a bit thin to me. I would get a professional opinion on that for sure.

If it helps, I can assure you that pm6 with crower 2 works and is at least good for 11.2:1 CR and 7500 rpm because thats what I run.
 

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Brokedick Millionaire
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those areas will be fine......

I doubt your gonna see much difference in weight between the four pistons.

You'll be able to sleep better at night opening the valve reliefs, which also help air flow :)

Bone approved :)
 

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Discussion Starter #7
Bone & Eyal, i got two good answers from you both! I will take the cue from you guys. Here's what i'll do:
I will use those pistons
I will grind off just a small portion of that ridge, particularly that upper part where it thins off (just enough to take out the sharpness and to make that area "sturdier). That way i'll eliminate a potential hotspot.

OH BOY! YOU GUYS RULE!!!!!!!!!Thank you!
 

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Curious George
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But clay your engine before and see clearances.

I had the same project, I have 2 set of four Pm6 sitting right on the shelf, I don't think I'll do it, maybe by grinding notches you touched a weak area on pistons, please go get a set of pistons who fit with valve position, anyway it's oem, or aftermarket. I don't think a couple hundred of $ will kill you, and it's cheaper than blowing an engine and pay a complete rebuild or trying find another engine.
 
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