What plugs are most people running in their AFR Headed LT1s with power adders? Specifically a plug that is 1-2 stages colder. A p/n and or stock number would be great.

Thanks,

Dave

 

tr6(4177) gaped .035

 

I hope not to get into another argument over this, but the NGK TR6 is a taper seat plug. The AFR's are machined for gasket seat plugs. A correct-style cold plug is an Autolite 3923. That is the second coldest available from Autolite, the coldest being 3922.

Mike

 

Yeah I thought you would post in this one mike

That being said, I have been using the wrong plugs for two years now, and will be goign with a gasketed plug this year. I was running the autolite 103's. NGK makes a gasketed plug I believe.

Bill

 

If my memory is correct, try an AC plug FR3LS or colder FR2LS. Those are colder than a stock heat range. I ran the FR3LS's on a 10:1 175HP N2O car with nice results. The FR2LS may be too cold for street use. Hope this helps.

 

I *think* that AC discontinued the FR3LS. At least that's what the guy at McDonald's, umm, I mean Autozone told me.

Mike

 

Thanks for the information. I ended up running an NGK -8 heat range of plug on the 150HP shot. Seemed to work well, I ran a 10.56@132.6mph. Did surge a bit on the the second pass on the big end...lifted some and ran a 10.73@126mph, but I think that was fuel related and really didn't matter because the track wasn't going to give me a third pass.

NGK's plugs are listed in a heat range of something like 5 to 11. Anybody know what the stock heat range plug would be considered? Or what a TR6 is considered? I will be spraying 250HP at the track next time I run and I want to run a 2 step colder plug. I am wondering if I am already their with the number 8 heat range.

Thanks again,

Dave

 

I have been researching this question and it's correct not to use a tapered seat plug in AFR heads. AFR stated that one reason to use a gasket seat is so the plug can't get welded to the head. On the other hand Combination motorsports says they use NGK TR6s in their LT1 blower applications without any problems.

 

Never knew that you had to run a specific style plug w/ AFRs. Yet ANOTHER thing they don't tell you I suppose.

 

http://www.airflowresearch.com/pages/210sbc_lt4.htm

Scroll down to the bottom and it specifies a spark plug. This information is also included in the owner's manual for the heads.

Mike