OK y'all (southern for you all). Today I decided to change plugs in my Truck and my 92 XJS. Truck is 35 thousandths, XJS is supposed to be 25 thousandths. So I merrily changed the plugs in the truck, then like a simpleton, set the plugs in the XJS at 35 thousandths, and buttoned everything back up. It seems to run fine. And since it is an unbelievable chore changing the plugs.....should I pull it back down and drop the gap, or will it be OK with the wider gap? Put Autolite iridiums in it for what it is worth.

 

there are a few old threads on this, but leave as is if all is well. With a '92 I believe you have Marelli? Just make sure you do not ignore consistent misfiring and keep an eye on the rotor cap insides. I have found the HE notoriously difficult to run well with iridium: They take less charge to fire and it seems the spark is a wee bit weak for the high compression charge in the swirl area. In addition the standard gap makes it fire a wee bit early and Marelli cannot be adjusted timingwise. Would be nice if you keep us posted, and also if somebody out there with in depth knowledge of the subject would enlighten us.

 

Decided to pull it apart again and set the gap at .025. Runs great, fuel economy picked back up. Thanx for trying to assist.

 

Interesting mine would absolutely not run iridium although I tried three different gap settings starting with book value.

 

You think it might be a difference in manufacturer?

 

I think it was NGK on my part so that may be the reason. That said NGK have always run well in my cars over the years. The engines and the use have been rarher verying. OTOH I cannot think of any other reason.

 

Normally I swear by NGK in Boat, Car, Truck, weedeater, chainsaw, but a friend had used these Autolite Iridium plugs in a restore Z28 Camaro and they worked great, so I gave them a try. So far, they are doing beautifully.

 

The Iridium plugs gapped at .025 seem to work very good. Except there is now static noise on AM radio.

 

AM? Who listens to AM anymore? Or FM for that matter. Just kidding.

Did you also change the wires?

 

Yes, put new wires on as well.
Talk radio is on AM mate and i hate to miss all the bluster! :-)