Spark Plug Gap Question

Im running the Champion truck plugs in my '90XJ. The FSM and Haynes manual says to gap the OEM plugs to 0.035". Out of the box the Champions were all gapped about 0.044". Is anyone regapping their plugs or other non platinum plugs to .035" or just putting them in as is? Im running mine without re-gapping but wondering if I should set them to 0.035".

I want the best for mileage since the price of gas keeps going up....

I always re-gap mine to to recommended gap.

I never knew they were gapped out of the box, at least not the aftermarket ones, the ones I get from the dealer are gapped at .035. When I change them every year or two they are generally around .055 or .060. Even so I check each one as I take them out of their boxes just to make sure. I keep one of those large halfdollar sized gauges handy for this. I think it's more important that they are all the same gap.

usually the plugs get used in different applications with different gaps.
I think they try to pre gap them approximately to some common use, but
really you need to check them to be sure.

What about different brands of plugs having ther own optimum gap that may be different from the OEM spec?

I always gap the plugs for my CJ, but the KJ plugs I get are NGK and they come pre-gapped. I check them, but they are so close, I usually don't have to re-gap.

I just got my XJ in Nov 04 and the PO had done a tune up not too long before then. I haven't pulled the plugs to check the condition yet. I was wondering if platinum plugs made a difference in the Renix engines?? My 89 4.0 is at factory specs, no intake or major exhaust mods yet.

Keith

I would not trust the factor gap as some plugs are more universal in application and have to be gapped to .035. Also, shipping may change the gap on certain brands.