Spark Plug Info for Drag Race Mopars ?

[Mike Gaines]

I run Champion RC12YC Plugs (14mm/.750 reach) ( $1.97 @Summit) on my INDY heads.
Gapped at .042 with MSD 6AL Ignition and MSD wires and MSD Blaster 2 Coil
I run 50% 91 pump gas mixed with 50% 110 VP Race Gas

Questions are for 100% drag race application (no street use)
Questions:
1) What plugs do YOU use ?
1a) In your opinions should I be using more of a "race" type of plug ?
2) What gap do you run ? (with what ignition system)
3) Most Important....How many runs do you think your plugs may be used before they need to be replaced with new ones ? (with the presumption that jetting and timing are correct)

Thanks

 

[Canyon707]

I use NGK racing plugs
msd 6al with msd wires
my plugs never seem to be worn
I gap .045
112 race gas
test and tune today at Sonoma raceway with new suspension

 

[66Satellite47]

Mike with my 500" EDE RPM head motor I've used the RC12YC & RC9YC plugs. 10.5 compression, Crane HI 6 ignition, .060 gap, 91 / 92 pump gas. I see lots of negative comments on the Champion plugs. I will check out the other brands this year. In the old days with my iron heads, I switched to NGK & Autolite plugs. Both of those seemed to work fine & last a little longer. That was with a 452" 906 or 915 head 12.5 + motor using 110 gas. I ran a MSD 404 BC ignition back then. I'm not at all sure how long plugs last. In the "old days" I'd change them after about 70 - 75 runs.

 

[ozymaxwedge]

.060 gap,

Holly crap .060 !!!

 

[66Satellite47]

Yup, high power multi spark ignitions shoot a wide gap. Long sparks fire fuel better. Check out the DC Bible & see what they say about MSD's and plug gaps. I've run the large gaps for many successful years.

 

[lewtot184]

an rc12yc may not be the best. i think the heat range may be a little hot. you can always experiment with some cheapie autolites from wal-mart, maybe 3923's. i check the ohms resistance on plugs anymore and a champion rc12yc had ten times more resistance than a comparable autolite 3924. i don't get lost in brands anymore. i just look for the heat range and tip design without excess resistance.

 

[dvw]

I run NGK. Easy to read cad plated electrodes. Put 300 passes on the set in the car. Car ran it's best MPH on it's 297th pass. So much for the theory that plugs need to be swapped often. I don't run the large gap, .030". On our turbo car even tighter .024". We've never seen a ET/MPH gain from a bigger gap. Making the spark harder to jump the gap adds to the possibility of misfire in my opinion.
Doug

 

[lewtot184]

I run NGK. Easy to read cad plated electrodes. Put 300 passes on the set in the car. Car ran it's best MPH on it's 297th pass. So much for the theory that plugs need to be swapped often. I don't run the large gap, .030". On our turbo car even tighter .024". We've never seen a ET/MPH gain from a bigger gap. Making the spark harder to jump the gap adds to the possibility of misfire in my opinion.
Doug

i've never found anything on wide gaps either. it does put more of a load on the ignition.

 

[Mike Gaines]

I use NGK racing plugs
msd 6al with msd wires
my plugs never seem to be worn
I gap .045
112 race gas
test and tune today at Sonoma raceway with new suspension

Canyon...what is the # of the NGK plug ?

- - - Updated - - -

I run NGK. Easy to read cad plated electrodes. Put 300 passes on the set in the car. Car ran it's best MPH on it's 297th pass. So much for the theory that plugs need to be swapped often. I don't run the large gap, .030". On our turbo car even tighter .024". We've never seen a ET/MPH gain from a bigger gap. Making the spark harder to jump the gap adds to the possibility of misfire in my opinion.
Doug

DVW...what is the # of the NGK plug you run ?

- - - Updated - - -

an rc12yc may not be the best. i think the heat range may be a little hot. you can always experiment with some cheapie autolites from wal-mart, maybe 3923's. i check the ohms resistance on plugs anymore and a champion rc12yc had ten times more resistance than a comparable autolite 3924. i don't get lost in brands anymore. i just look for the heat range and tip design without excess resistance.

Lew..would you say run the 3924 Auto lite or the 3923 ? Thanks..Mike

 

[Phil McGrath]

Mike with my 500" EDE RPM head motor I've used the RC12YC & RC9YC plugs. 10.5 compression, Crane HI 6 ignition, .060 gap, 91 / 92 pump gas..

Holly crap .060 !!!

No your mistaken, that's Holly Gap!!

 

[lewtot184]

Canyon...what is the # of the NGK plug ?

- - - Updated - - -



DVW...what is the # of the NGK plug you run ?

- - - Updated - - -



Lew..would you say run the 3924 Auto lite or the 3923 ? Thanks..Mike

the 3924 and rc12yc heat ranges are about the same. the 3923 is one step colder. neither have the high resistance of the champion. they seem to be a reliable cheap alternative for testing, i use them. there is a step colder than the 3923 but i'm not exactly sure about the number. the 3923 would be close to a 10 heat range in champion. i would try something a little cooler than a 12 heat range for racing.

 

[Hemirunner]

I run NGK. Easy to read cad plated electrodes. Put 300 passes on the set in the car. Car ran it's best MPH on it's 297th pass. So much for the theory that plugs need to be swapped often. I don't run the large gap, .030". On our turbo car even tighter .024". We've never seen a ET/MPH gain from a bigger gap. Making the spark harder to jump the gap adds to the possibility of misfire in my opinion.
Doug

Same here and X10. Those RC12YC plugs are way too hot for most pump gas combos today. NGK8 will work great. I run .035 gap on most NA combos and anywhere from .016 to .028 on the turbo stuff. I can't read those autolite plugs for **** so I don't use them.

 

[HEMI-ITIS]

I use NGK 8's.They are $20 a set.Street driven gapped at .35,making a pass just cleans 'em nice. I have a large collection of 7's,8's,9's and even tried 10's. Some of these plugs only have 3 passes on them. I'm a tuna fish chasing an E/T.
If you ever run into me,I always keep at least 4 plugs under my seat:eusa_whistle:

 

[Hemirunner]

We spray on 9's and my buddy runs 9's in his F2 procharged SBF as well.

 

[dvw]

I use NGK 5671 A 8 at 15-1. Less compression might like a NGK 7
Doug

 

[theman440]

I run Autolite 3934's @ .045 gap, with a MSD digital 6 box. I've never kept track of how many runs I get.

 

[ozymaxwedge]

At the track for years I was changing plugs out nearly like my undies, new set every second meeting until one day I was taking to an old guy that has been racing for 35 years, he said "Don't waste money Al, the set that's in my car now have been there 6 years, and when the it gets a miss I'll change em" He is dead right, now I don't buy plugs, **** I have 100 used ones that have maybe done 2 hours.

 

[Mike Gaines]

Ozy...What brand and number plug to YOU run ?

 

[Tex013]

Mike ,
I run the NGK BKR6E plug gapped 0.038 .
I will put a new set in at the start of the year . Maybe change them mid year , BUT , I do drive my car every day to work and home .
Heck I just drove the Plymouth to Melbourne 2 weekends ago to race and home again . 9 1/2 hrs drive each way .
I did try 2 years ago putting new plugs in every meeting , found no gain at all , but a few barely used plugs :toothy9:

Tex

 

[ozymaxwedge]

Ozy...What brand and number plug to YOU run ?

Mike I run, BCP6ES NGK Plugs, they are slightly shorter plug which gives a little more clearance to some header pipes.

Barracuda has Indy heads, MSD 6AL Plus, Locked MSD Pro Billet and blaster coil.

1963 Belvedere has Indy heads, Crane HI6, MSD Pro Billet and Crane PS92 coil.