Last night, I decided to pull my plugs and check the gap, as well as check for heavy deposits on any of them (developed a slightly rough idle). What I found is that the gap had gone from 0.040 to over 0.045 (my gapping tool only goes to 0.045) in the 3 thousand miles or so since I last checked them. Also, #8 had oily threads and some black crust on the ring around the center electrode. The center electrode, side electrode, and porcelain was a light tan as it should be. #7 had a little oil on the threads as well.

The plugs are NGK V-Powers in the stock heat range. The only mod that I have that relates to the engine is a Magnaflow cat/flowmaster 40 series. There's no vacuum in the crankcase, but it looks like there might be a small amount of oil in the very back of the intake manifold. I'm getting no pinging.

Any ideas?

 

possibly valve seals are needing to be changed. Does it smoke at all when you first start it? If so does it go away after a minute? If it does, that's where i'd start looking is at the valve seals.

If it turns out to be the seals, here's how you can change them without having to take the heads off or worry about dropping a valve into the cylinder. get you some 3/16 nylon rope and with the piston down feed it into your cylinder through the spark plug hole. once you get quite a bit in there, turn your crank to push the piston back up and it wedges the rope against the valve. Then you can replace the seal without the valve dropping down. When you're done do the same with the next cylinder. piece of cake.

 

It doesn't blow any smoke on cold startup (or at all, actually). I know both valve covers are seeping slowly, but it's just gummy around them and not actually running/dripping anywhere. I guess it's probably Plenum time.

Any ideas why the plug gaps would have widened so much in suck a short time?

 

I agree, check the plenum.

 

your spark gaps could have widened from being too hot. like you're running real lean. Check your fuel filter and injectors. That's the best i can think of for such a short time.

 

Are the NGK V Power plugs a platnium plug? I had the same problem with a set of plat Autolite plugs in mine. I drive about 200-300 miles a day in mine, so I noitice wear and tear pretty quick. I gapped those plugs to .35 and in two months I pulled them to check them. I didnt have the deposits on mine, but they were now gapped to .65~.75.
I put a regular plug in them ( the 3923 Autolites) and have not had an issue yet. in fact, I pulled them last week end to check them.