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can I mill pistons ?

Posted By: Wedgeman

can I mill pistons ? - 11/03/11 01:07 AM

One tought....

Can I mill a set of pistons to get the right dish volume for my combo?

ie.: a set of Diamond piston with a volume of 6.8cc, I could shave 2 mm of the top to have a 10 cc dish
Posted By: 6bblFLASH

Re: can I mill pistons ? - 11/03/11 02:00 AM

Depends on the thickness. I would suggest contacting Diamond Pistons
Posted By: Performance Only

Re: can I mill pistons ? - 11/03/11 02:06 AM

Quote:

One tought....

Can I mill a set of pistons to get the right dish volume for my combo?

ie.: a set of Diamond piston with a volume of 6.8cc, I could shave 2 mm of the top to have a 10 cc dish




well, 1 mm = 0.039370 " so you want to mill almost .080" off the top? is this a flat top that want to turn into a dished piston? what is the part # of the piston?
Posted By: Wedgeman

Re: can I mill pistons ? - 11/03/11 02:55 AM

yes, it is the flat top piston for 408 strokers
Dan
Posted By: dOoC

Re: can I mill pistons ? - 11/03/11 03:00 AM

NEVER had a custom aftermarket piston made for me-self before ... but I would contact Diamond FIRST. They could have been made SUPER LITE ... then there is no way to cut anything off them safely.
Posted By: Performance Only

Re: can I mill pistons ? - 11/03/11 04:15 AM

do you have the part # ?
if it's a shelf piston your going to get pretty thin below the valve pockets. they're probably about .200" thick in that area with that forging. easy enough to measure though.
Posted By: HP Engines

Re: can I mill pistons ? - 11/03/11 05:08 AM

Hey Wedge, Usually when I run into this situation it deems easier to
use a thicker head gasket,and/or to mill the combustion chambers out in the cyl. heads. to the required cc. Also you only have to set up 2
heads versus setting up 8 individual pistons in the vise. Another thing to keep in mind is when you mill pistons, this will change
the bobweight of the rotating assembly, and thin quench pad.
Cometic will make any thickness of head gasket to your spec if not shelfed.If all else fails, order custom pistons and wait 2 weeks.
However you hash it out, I would try to retain a squish factor of
around .040 - .050 for optimal volumetric effiency.
Hope this info can help. GOOD LUCK!
Posted By: Wedgeman

Re: can I mill pistons ? - 11/03/11 10:32 PM

Thing is ....
I have 55cc chambers indy -1
20.5 step dish pistons KB745
.041 cometic gaskets
255*/263* roller cam

and 10.75 static comp ratio.

I want to raise comp and still use premium pump gas......

Dan
Posted By: AAR-B4

Re: can I mill pistons ? - 11/03/11 11:56 PM

Don't do it without a fixture to hold them.
You can't tighten them in a vise without possibly deforming them.
Posted By: dOoC

Re: can I mill pistons ? - 11/04/11 12:36 AM

Quote:

Don't do it without a fixture to hold them.
You can't tighten them in a vise without possibly deforming them.




...and on this same-vein ... THIS is why most people who build PS moders(so I have been told) ...do ALL machine work BEFORE putting in ring grooves.

Any machine work AFTER the grooves are put in .. it can distort the piston.
Posted By: HP Engines

Re: can I mill pistons ? - 11/04/11 02:02 AM

I hope anyone capable of machining pistons, knows to clamp them
in a piston vise (or fixture), and not a vise off the railroad.
Wedge if you need to cut .080 off a new piston, to gain compression,
sounds like comp.height of piston is off. I would consider different pistons with a better baseline spec.
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