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Best plug for a RENIX and what gap?

xjtrailrider

NAXJA Forum User
NAXJA Member
Location
Roanoke VA
Yes I have searched, most of the RENIX plug threads are old.

I'm needing some new plugs for my 90. Right now I'm running the "run-of-the-mill" Champs and get decent mileage but since I put those plugs in I have added Taylor 8.8 wires, Accel cap and rotor and a new coil. In the past I have run NGK V-Power 7373's with good luck and longevity but I know that 5-90 really likes the Autolite Platnum AP3924.

I think I can go to a wider gap with the updated/upgraded ignition system, I'm thinking around .040

What is everyone's thoughts on this gap?

What would be a good all around plug for mixed driving and towing?

Would the standard heat range be ok? I do get some light pinging on really hard pulls towing.

I'll add that my RENIX is newly rebuilt with only 15k on it, it has been bored and decked. The head has been reworked and all sensors/outputs are new including the fuel injectors. Basically if you can think of it on this Jeep its new! It runs great and gets around 16 in town and 22 highway. I use to get 18 in town and 24 highway when I first broke the engine in.
 
I use the recommended NGK V power, at .4, with stock coil and Accel 8mm wires.
 
Champions work as good or better than the fancy plugs, especially in a stroker. The multi electrode plugs don't seem to work that well in the 4.0L.
 
I used Bosch plat +4s, and they sucked. It runs best with a standard plug.
 
I run the champion truck plugs with no complaints with factory gap on my 89'
 
OK so I have narrowed it down to following 3;

NGK V-power 7373
Champion copper plus RC9YC
Autolite platinum AP3924

Any other suggestions?

The general consensus is that a .040 gap will work just fine and that the factory specified heat range is OK.
 
I've confirmed that the 7373 is indeed what I am using. The only other NGK plug that they recommend for this engine is the 3248 platinum, which I have never used.
 
The factory figured OE specs on plugs knowing the frequency of tuneup they recommend, the nature of the ignition system, combustion chamber design, and the need for multiple electrodes. What they spec is all that's needed - but no less.

I just get a little sad when folks come in wanting "8-track" plugs in their "Bose CD" ignition system. It's false economy when the proper iridium plug goes 75,000 miles with the coil on plug setup, and I feel it's excessive to screw in $6.00 plugs when the system doesn't need the edge of the envelope performance.

Renix systems use a inexpensive plug well, probably because Renault-Bendix made it work for the world market first.
 
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