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Nov 20, 2016 | 10:22 AM

WS.SIX

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Stupid question...

Stock 821 cylinder heads. One was milled .005 to clean up. Any issues running as is or do I have to get the other head milled .005?

Nov 20, 2016 | 10:35 AM

KCS

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I would have the other one done too, but I don't think it will really hurt anything. It's about 1cc in chamber volume for every .006" cut FWIW.

Nov 20, 2016 | 01:13 PM

pantera_efi

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Head C/C's

Hi, I have done this to CORRECT problems.

My method is to C/C both heads, you may find them equal.

Remember, that distance is about two hairs, the ones on your scalp.

Lance

Nov 20, 2016 | 06:20 PM

lowcountry

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^^ What he said...

Nov 21, 2016 | 02:43 AM

Kamaro

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Factory heads will vary in CCs as much as this, or maybe even more.

Nov 22, 2016 | 01:16 AM

WS.SIX

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Bought a CC kit and will check them out. How much of a variance is safe between heads?

Nov 27, 2016 | 05:42 PM

WS.SIX

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CC'd the heads today. One head is 70cc across. The other (milled .005) is 69cc across with one dipping down to 68cc (head had some damage that was touched up)

Thoughts?

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Nov 28, 2016 | 12:04 PM

pantera_efi

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CC = CR = Change Value

OK, good work.

The difference is RELATED to final CR.

The 12:1 you would have a measurable change, the 10:1 little change.

What will be your target ratio.

I would increase the 68cc chamber.

The heads operate at different temperatures, I would put the Higher-CR on the cool side.

Lance, BTW a "bit" of a Speed Secret

Dec 1, 2016 | 01:12 PM

#10

WS.SIX

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What side is the cool side?

Dec 1, 2016 | 07:35 PM

#11

MuhThugga

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From: Wilmington, De

Hit a jukebox on each bank and whichever one gets it playing is the cool side.

Last edited by MuhThugga; Dec 1, 2016 at 09:10 PM.

Dec 1, 2016 | 09:20 PM

#12

WS.SIX

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Really love how this website has went down the crapper with these useless replies... damn shame.

Dec 1, 2016 | 10:28 PM

#13

JakeFusion

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I'd just mill the other side. I try to take as much variance as I can out of the motor. Of course, it runs with as much as 5-10% variance anyway given weather and other factors. So in the end, it wouldn't hurt anything.

And is the cool side where you turn your pillow over at night?