spark plugs for GT-40X heads
 

Hello,

I have a question on some spark plugs. I have the GT-40X heads on a 331. I was just changing the spark plugs which are autolite 764's. It has been at least 3 years since I have changed them. One of the plugs in back on cylinder 4 was a champion RS12YC and the other 7 were the 764's. I remember after pulling them that I had broken one of the plugs and that is why I must have put the champion back in. The problem is, is that the autolites have about 3/8 long thread section that goes into the head and the champion have 5/8. I guess I didn't compare them when I had them out. Are the autolites I have been running not reaching in all the way into the combustion chamber? So I need to know if I need a long treaded plug. I can't get my head down far enough to see.

Re: spark plugs for GT-40X heads
 

I think the champions and motorcraft are that way, i run the 764's on my iron's, and I think i noticed shorter thread on the autolite then the motorcrafts, I dont have any experience with the 40x heads, but I would't worry, either plug should work fine.
Hey meknized, your combo sounds badazz for a street car, is your e.t. on street tires, or stickies?
sounds like a similar combo im looking to build someday, you ought to get high 11's 110+ out of that though.

Re: spark plugs for GT-40X heads
 

Hey,

Thanks for the response. What threw me was that the autolites had a shorter thread then the champions. But the electrode depth was the same. Oh well had to make sure. :o My current best time is a 12.02 @ 112 60ft. 1.7. That was on M/T 10X26 slicks. 12.5 @ 109 on radials. My launch was roughly at 3500 rpm or so. I know I can hit an 11. That particular day there was a 12 mph head wind, not saying that I would have hit an 11 but I think I could have maybe knocked out that last .03 of a second without it. I'm still learning to launch on the slicks and could launch harder, but I don't get out to the strip as much as I would like to practice. Always fun though!! :D
There is some pictures of my car on www.haiokuracing.com during a imports vs domestics at our local track. click on past events at the bottom on sun May 14th. I'm the blue and silver GT.

Re: spark plugs for GT-40X heads
 

Nice man, id like to see a video run of your car, That combo, with a tremec especially, should see high 1.5, or low 1.6 60's with a hard launch....later