Trying to find a colder spark plug

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Aug 28, 2015 | 06:48 PM

Cummins93

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CF Veteran

Joined: Mar 2015

Posts: 1,203

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From: Northern CT

Year: 1995

Model: Cherokee

Engine: Turbo 4.0

Trying to find a colder spark plug

Application is a 1995 jeep cherokee 4.0. I'm looking to go a stage colder than stock. If anyone has some numbers for me that would be great.

Aug 28, 2015 | 07:01 PM

EZEARL

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Joined: Aug 2009

Posts: 5,676

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From: WV

Year: '96

Model: Cherokee

Aug 28, 2015 | 07:02 PM

Rogue4x4

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Joined: Feb 2011

Posts: 14,479

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From: Blunt, South Dakota

Year: 97

Model: Cherokee (XJ)

Engine: 4.6 stroker

Why?

Aug 28, 2015 | 07:15 PM

4WD4EVER

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Joined: Sep 2012

Posts: 1,623

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From: In a large sandbox

Year: 1998

Engine: 4.0

I believe the Champion RC10ECC is the next coldest plug for the Xj's, but like roninofako asked, "Why?" Sometimes a colder plug does nothing but mask underlying symptoms that may need looked at first.

Aug 28, 2015 | 07:20 PM

ehall

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Joined: Jan 2015

Posts: 1,381

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From: Southern Maryland

Year: 1991

Model: Cherokee

Engine: 1999 4.0L

I used the Autolite for RENIX applications, its a little colder

Aug 28, 2015 | 08:01 PM

Cummins93

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CF Veteran

Joined: Mar 2015

Posts: 1,203

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From: Northern CT

Year: 1995

Model: Cherokee

Engine: Turbo 4.0

I have a wh1c mocked up. My current plugs are high milage so might as well drop the range on them. Thank you for the part number.

Aug 28, 2015 | 11:54 PM

Cummins93

Thread Starter

CF Veteran

Joined: Mar 2015

Posts: 1,203

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From: Northern CT

Year: 1995

Model: Cherokee

Engine: Turbo 4.0

http://www.sparkplug-crossreference.com/convert/champ_pn/rc10ecc

Using the site above, and rc10ecc as my search I came across the NGK colder plug, the ZFR6F11. Which adds some fun because this is the response that I got back from a tech at NGK. My compression ratio is 8.8:1.

Thank you very much for that information. Since you lowered the compression ratio, and added boost, it evened it out, so you can run your stock plugs, which is FR5-1 (stock# 7252). Because of the extended metal shell design on the thread, it is a very specific plug, which narrows your choices down. After few runs, please pull the plug to make sure they look good.