Usually the flame throwers put a fuel injector in the tailpipe too. Otherwise you'll only blow flames when you get off the gas and that will often happen without a spark plug. And the flame from fuel/air burning at atmospheric pressure is not nearly as problematic as the same mixture burning at 11:1 compression.

UL

 

Got a 5/8" plug socket today, but found I don't have the correct size allen wrench to remove plug access cover.

Can anyone tell me what size allen wrench I need, or do I need get a whole new set?

I plan to regularly check the plugs myself from now on.

 

OK, well Gregg and I visited my car yesterday and we saw the damage...

Get this...the top of the spark plug was bent by about 70 degrees, totally scorched and broken to bits. There was a ton of remnants in the cylinder and on the piston that looked to us like broken spark plug porcelein. The coil looked like a bowl of spaghetti and we saw the retainer on the one #1 valve that was broken, but it hadn't let go of the valve. The valves in #1 were scorched terribly...

But check this out...the wall of the cylinder on about 1/4th around the wall were nothing but grooves. Rather deep grooves that surely would have had an effect on compression. It was obvious to us, at least, the skirt was causing this. The compression test that they had done was not that effective because the the threads in the head were just about trashed. The plug's threads were in tact, as I had reported earlier. But the spark plug was hardly recognizable as a spark plug...

So, we took a ton of pictures...we are here in Indy after an AMAZING qualifying today. Holy cow...a new record was set and that was broken right afterwards. Totally freaking awesome...

I will be home tomorrow night and post the pics. We also got the shots of the new block still in the box...

And just so everyone is clear, the bottom ends, as well as the heads, come completely assembled and ready to go. No assembly or anything is req'd by stateside technicians - it's more or less simple remove and replace kind of thing.

So anyway, stay tuned for pics and more answers to the questions tomorrow. It was fascinating to see the motor like this. I'll ask Gregg to post his impressions. In the meantime, we have beer to drink and BBQ to chow on.

 

[QUOTE]Originally posted by DougM
[B]Can anyone tell me what size allen wrench I need, or do I need get a whole new set?

 

[QUOTE]Originally posted by gregstevens
[B]...the wall of the cylinder on about 1/4th around the wall were nothing but grooves. Rather deep grooves that surely would have had an effect on compression.

 

How do you torgue the cover back if you open it with an allen wrench?

 

I meant torque

 

Hmm, very interesting Greg. I have a whole lot of questions running through my mind right now but none of them make anysense.

How the hell did the top of the plug bend - something must have hit it really hard or it must have hit something! - but what?? Would compression alone (or together with combustion detonation) apply sufficient force for it to shoot out and bend the plug head on the plug cover? Is the plug cover that hard that it would cause the plug to bend if it hit it?

Did the piston somehow contact the plug? Or did the loose plug jiggling around bend itself?

I'd certainly like to get to the bottom of this!

 

I didn't bother with a torque wrench to put the cover back on, but 5mm allen wrenches are available to fit onto your 1/4" or 3/8" drive torque wrench. Basically, it's a piece of 5mm hex stock strongly attached to an adapter to fit the square drive on the wrench. Sears has them!

Greg - thanks for the update, enjoy the show!

 

That is my guess.. that a loose plug contributed to a lean situation and big detonation just as the plug was coming loose. The plug was probably ejected forcefully enough to bend, destroy the coil, and smacked the threads on the way out knocking porcelain into the cylinder.