Spark plug recommendation

[fekbmax]

So, know this is a very general question but,
What kinda plugs do you racers like for all out strip duty in hi compression, aluminum Headed engines ? Brand, type, ect. Which one has the widest selection of heat ranges that are readaly available ?

[jayb]

I like Autolite racing plugs, AR3923.  Work great for me on the track and the street.

[blykins]

The AR 39 series is what I use the most.  My 13.5-14:1 stuff gets AR3910's but I use a lot of 3923 and 3924's as well.  Good plugs.

[Lenz]

Layman's question, but what design characteristics are built into the racing plugs that help them to perform in a more extreme environment?  I'm still running my first set of 3924's in the 445, certainly been issue free for street duty. 

[e philpott]

I'm searching for a new brand and leaning towards NGK .... the Autolites my shop has seen in the last year has made us not order anything from Autolite anymore as of a few weeks ago , the quality control seems terrible right now and have had a few cars come back for miss that were all spark plug failure along with a new set of AR's for my own fe car that ran terrible right after being installed

[fekbmax]

Thanks guys.
What's the NGK number's ?

[KMcCullah]

The number to the NKG plugs I've raced is R5671A-9. I prefer the Autolite 3911. The Autolite Racing AR39** series of plugs have the shortened ground strap. Setting the gap on those gives me fits. But I've won a few races with them....

[IDOIT4SPEED]

 in my old Windsor head 289 and 331. when I ran out of autolite BF22. I switched over to NGK AP8FS, ran good looking for more power. I got some Auotlite AR33. motor ran better. but the plugs were crude at best, had four sets. picked out the best ones to make three sets. took the rest to the nationals at BIR  talked to the autolite rep at there service trailer. said whats the deal with these plugs. the rep took the plugs, gave me a set to replace the bad ones, and another for my trouble. OK? the block split in the 331, start over with a 348 ci dart sb  started out with NGK R5671A8 had room for extended tip switched to R5672A8 it ran better! next I got some Autolite AR3911 ban better yet. then something odd happened, I got some Champion C61YC the car picked up a lot, night and day difference, and I hate champion plugs. not any more. thats what I am running now, some plugs just run better than others. not the first time I have seen this