Racers, What plug you running?

[kdtjb]

I have Indy CNC ported heads, running 12:1 compression, with a .620 lift roller, I burn 110 octane fuel. I have been running autolite 3923s, but was told these were too hot. What do you think? Thanks, Kent.

 

[Endangered Species]

That is a pretty hot plug. We are running Champion C63YC's which equate to the Autolite AR3911 - with 14.7:1

I would ask your engine builder what he thinks. If you don't feel comfortable then I would go colder, like a 3910 or 3911.

 

[Stumper]

I have a very similar engine and have used AR3934 and AR3935 plugs - but I'm also not sure I have found the right ones either. I admittedly have not been running my car on the strip much these days and around town even these plugs look like they came out of a wood stove flu after a few hours of running.
How do your plugs look after a few hours of run time?

 

[kdtjb]

The color looks OK but I had some one look at them that has a dyno, and he said there was a heat ring on the threads. I have ran this plug for quite awhile. I started fighting a problem this year of getting to the line. It runs fine at full throtle, but in staging and going back to the pits it does'nt run smooth at all. Rich I think, because it seems to clean up in my burn out. I know that's not my plugs, but in trying to solve it the plug issue came up.

 

[SUPERSTOCKRACER]

i would never run a champion plug again.
3 friends had electrodes break off and drop into their motors causing catastrophic failure.
Champion plugs started getting cheaper right around 2000-2001
All the early 1960's to 1990's were great plugs.
I only use NGK.
5672A-8 for flat top piston
5671A-8 for dome pistons

 

[Bbody540]

NGK R5672A-9 vp race fuel 108 octane 12.66 comp. indy sr stage 1 port

 

[Endangered Species]

i would never run a champion plug again.
3 friends had electrodes break off and drop into their motors causing catastrophic failure.
Champion plugs started getting cheaper right around 2000-2001
All the early 1960's to 1990's were great plugs.
I only use NGK.
5672A-8 for flat top piston
5671A-8 for dome pistons

I agree... I just have to convince Joe of that.

Throught my experience with Racing Sleds and working in speed shops. Autolites are the best for high compression/high cylinder pressure applications.

 

[SUPERSTOCKRACER]

yes autolites are good too. i run them in my pure stock A12 Superbee

 

[fugly]

Autolite AR3933 for that one I think....no Champions for me either

 

[the64dodgefan]

autolite with VP fuel 15:1 compression