Is there any benefit to a larger spark gap, like 0.35 to 0.45 ? Thank you !

 

Unless you have an upgraded coil, it's likely you would loose power from that...I don't have any personal experience with it, but anything I've read about it in the past suggests that.

 

Just curious I went to a shop and they said the plugs are pre gapped. Would that sound correct?
I have a GMC jimmy it has a 4.3 engine in it.

 

yes that is correct

 

Thanks , its good to know that, I have a lot to learn.

 

Never trust the factory plug pre-gapping. Always check it before installation.

 

Thanks maybe that is what I need to do , even after the tune up with new plugs and wires and the rotor cap it just does not run smooth like when I first got it. It rough on a cold start.

 

+1 on this. My 95 spark plug gap spec is .045. Yours could be different but you should never deviate spark plug gap away from factory spec and double check the gap of every spark plug. Might not be your problem, but i used to have a every once in a while rough start. I replaced my spider injector and it seems to have gone away for now. Shouldnt do that though unless you are sure that is the problem.

 

Absolutely confirm the gap yourself. I also put myself through the pains of indexing my spark plugs.

 

I agree with that, But I installed a MSD Coil, Cap & Rotor and a new set of AC Delco Professional wires. I wanted to step as I don't do a lot of long hauls. Mostly short errands. It's only 0.10 over and the plugs are identical side by side ?