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Old July 28th, 2013, 09:11 PM   #1
6spdWillys
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Default machining 4.0 head. How much is too much?

So it seems the cam gear and OPDA drive gear in my Wrangler has finally given all their teeth so It's time to install the OPDA upgrade and a new cam/lifters and mill the head, among other things.

My question; How much can I safely mill the head to give it a bit more compression/power while still playing nice-nice with the stock computer, etc.

It's my '05 TJ, 4.0 and NSG370 6-speed trans. About 84,xxx miles on it now.

Anyone done this yet? Suggestions appreciated. Starting to tear the head off tomorrow to get it to the machine shop in time to have it back by the weekend for installation.

Thanks.
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Old July 31st, 2013, 06:55 PM   #2
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i machine .012-.015" off all 4.0 heads. if ya want a bit more pop, the mopar perf gasket is a bit thinner than stock also. never had any issues yet, cutting 20 off the next one
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Old August 1st, 2013, 01:52 PM   #3
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www.jeepstrokers.com will give you an idea of what amount results in what CR in their calculator
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