Not sure where I got 9 from, think that's my lawn mower plug haha. They are rc12lyc. So I'm missing a 4.

Not a big fan of Bosch O2 sensors in our beloved 4.0s. Prefer NTK.

Prefer NGK plugs also. Same company as NTK.

I looked at the website you gave, and even though the part number is 412, it shows rc12lyc.

Either way I'll switch out for the NGK plug's and see about getting the o2 sensor. What's the number for NGK that you use?

7373s

I can't find a heat range on summits website for the champions, but the ngks are at 5.

Don't worry about it.

Just curious. I'll update later, about to hit every roller coaster at Busch gardens lol

I think each manufacturer's heat ranges are relative to them and not others anyway.

Have fun on the "puke" rides!! I can't do them anymore. LOL.

Haha most of our rides here aren't too bad.

Another thing I forgot to mention is that before the rebuild it seemed to run rich, with a black sooty tail pipe, even with that new o2 sensor. Hmm. I suppose a NGK sensor is in order.

Got the spark plugs. Had the pleasant surprise of finding 3 or 4 freeze plugs are leaking. Bad enough that its dripping on to the exhaust. What the ****.

Calling up the damn ****** who put this thing together tomorrow.

Switched them out. Cylinders 2 and 6 look fine, the rest are the same.

At idle spray carb cleaner along where the intake manifold meets the head. If there's a vacuum leak, you'll know it.

Okay give me a few

A few what?

Beers, dollars, anything.