Just a few words on spark plugs.

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Nov 18, 2016 | 11:32 PM

#151

Comanche91

Junior Member

Joined: Jan 2014

Posts: 31

Likes: 1

From: Sweet Home Alabama

Year: 1991

Model: Comanche

Engine: 4.6L Hesco Stroker

Okay - nice pic. The physical construction of the plugs is different but the reach looks the same. I already knew that.

If you're recommending one over the other, why?

Nov 18, 2016 | 11:35 PM

#152

cruiser54

::CF Moderator::

Joined: Aug 2011

Posts: 43,971

Likes: 1,579

From: Prescott, Az

Year: 1990

Model: Cherokee (XJ)

Engine: 4.0

I've always used NGKs. Replacing FR-1s that only had 10K miles on them with the ZFR5Ns yielded a noticeable difference in performance.

Nov 18, 2016 | 11:51 PM

#153

Comanche91

Junior Member

Joined: Jan 2014

Posts: 31

Likes: 1

From: Sweet Home Alabama

Year: 1991

Model: Comanche

Engine: 4.6L Hesco Stroker

Most likely in stock engines in your case, si? WTH, I'll give them a try. Anyone else have any experience? I didn't get any reply as to the actual differences between the two except for physical construction.

Nov 19, 2016 | 09:31 AM

#154

cruiser54

::CF Moderator::

Joined: Aug 2011

Posts: 43,971

Likes: 1,579

From: Prescott, Az

Year: 1990

Model: Cherokee (XJ)

Engine: 4.0

Lightly modified but no big deal.

Nov 23, 2016 | 05:54 PM

#155

Comanche91

Junior Member

Joined: Jan 2014

Posts: 31

Likes: 1

From: Sweet Home Alabama

Year: 1991

Model: Comanche

Engine: 4.6L Hesco Stroker

Threw in a set of ZFR5N NGKs today and it did improve the idle quite a bit. This along with a Mopar TSB 08-35-93 ignition coil / harness kit install and the relocation of the coil from the hot engine block (posted HERE) has made quite a difference in the old stroker's overall smoothness and throttle response. It also has less engine turn-over time when starting. Hopefully this will all translate into a bit better "around town" mileage than the current 13 MPG.