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I hope to get some info on hard anodizing pistons. I've got a nitro Harley that I want to hard anodize the pistons. Customer wants me to put skirt Teflon buttons in them. I have done the hard anodizing in a Procharged BBC that made 1500+ HP. After over 100 hits, we took it apart, & it looked like new. I'm told by a very knowledgeable man that all the clearances will be changed. All we had to do to our pistons, was hone the pin bores, & we opened up the cyl. bores + .002.Rings went in ok, with a minimun amount of sanding with 400 paper on a surface table. Basically the same as any other build. What should I be looking for because of the nitro application. I asked a guy that was a crew member on a nitro car & he said buttons are seriously "old school" . Any help is greatly appreciated. We had good luck with this in the past, but , I don't want to miss a beat on this one . If this is not in the right section, please advise where to post. Thanks guys
 

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I run hard anodized pistons in a blown gas and blown alcohol engine. Also help run a FED injected nitro dragster. The piston manufacturer will tell you what clearance to run with there hard anodized piston. Usually the clearance is less than non anodized due to less expansion of piston.

Yes, forget the buttons with todays pistons.

Blessings......Ron
 

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To be clear, I'm talking about teflon buttons installed in the piston skirts.
I understand, you will not need them with hard anodizeding.

Blessings........Ron
 

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What's wrong with pin buttons other than adding weight? I love using them especially when oil ring is in pin
Nothing wrong with pin buttons, I currently run them

Blessings..........Ron
 

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Hard anodizing will add .002 on all surfaces including top, bottom and inside edge of ring lands. You will probably have to account for that in the machining. Talk to who does your anodizing and determine how much wider and deeper your ring grooves need to be and bore diameter.
 

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Hard anodizing will add .002 on all surfaces including top, bottom and inside edge of ring lands. You will probably have to account for that in the machining. Talk to who does your anodizing and determine how much wider and deeper your ring grooves need to be and bore diameter.
Not doubting you Curly, but that's hard to believe. I've seen coated skirts end up with a .001 on each side, but you're saying hard anodizing will add .002" to the ring land width, depth, pin retainer groove, and wrist pin bores?
 

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Not doubting you Curly, but that's hard to believe. I've seen coated skirts end up with a .001 on each side, but you're saying hard anodizing will add .002" to the ring land width, depth, pin retainer groove, and wrist pin bores?
Yes, The hard anodizing I have done on my compressor parts add .002 every where and we have to account for it on all of our machining dimensions or the parts will not fit together.
Talk to who ever is doing your anodizing to see exactly how much theirs adds. They should be able to tell you.
 
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