Question on Champion GN1 heads-12mm Spark plugs?

[czimpel]

I have been doing some shopping and research on a set of aluminum heads for my GN. I've put most of my time into the TA Performance and Champion GN1 heads.

I was able to take a look at a set of newer Champion GN1 cylinder heads this week, and I noticed that they use a 12mm spark plug hole instead of the standard 14mm plug. Not only does the 12mm thread seam to be a problem, but you also can't get an 18mm socket in the spark plug hole to use an 18mm hex head plug. This limits the use of only a 12mm plug with a 5/8" hex head. The plug selection is very limited to fit these conditions.

I've looked at NGK and Champion plugs, with little to no success on finding a plug with non-projected tip, and to have a selection of heat ranges.

What are some of you guys doing for plugs in these heads.

I've also heard some stories of the Champion heads cracking, is this true?

Thanks in advice for any advice or information.

 

[psycho6cyl]

I think champion hesds crack were their first run of al heads. If youre buying new I dont think that would be a problem. If buying used do some research,I think theres certain date codes to stay away from. If youre anxious to do the motor or on a deadline call ta and go that route. Champiins can take awhile sometimes

 

[larry33kc]

I run AR 3933-3934 plugs in mine with no issue

 

[czimpel]

I run AR 3933-3934 plugs in mine with no issue

Those are 14mm thread, the new Champions are 12mm!

 

[czimpel]

I think champion hesds crack were their first run of al heads.

So, did Champion fix the crack issue by going to a smaller spark plug thread?

 

[coach]

Cory...
Autolite Racing AR3932 is what I am running.

 

[Phoneguy]

Cory...
Autolite Racing AR3932 is what I am running.

Donnie, that is also a 14mm plug.
He is stating that the plugs are now 12mm.
I personally have not seen or heard of this and do not understand why this would have changed

Bryan

 

[coach]

Shit...never checked. Just commented...

 

[Nick Micale]

Donnie, that is also a 14mm plug.
He is stating that the plugs are now 12mm.
I personally have not seen or heard of this and do not understand why this would have changed

Bryan

I had not heard of this either, but I did see a new set of Champion heads with 12mm plugs so it must be the newest version of GN-1's?

So far the owner has not been able to locate a proper race plug in the 12mm size.

As far as the cracking issue, I will let others comment with their personal comments.

 

[larry33kc]

Those are 14mm thread, the new Champions are 12mm!

I'm sorry wrong plug I'm running AR 4132- 4133

 

[czimpel]

So basically there are only 2 heat ranges to choose from. I find it really strange that Champion would do this with their heads.

 

[czimpel]

Here's a link to the Autolite plugs if anyone is interested.

http://www.jegs.com/pdfs/autoliteracingheatrange.pdf

 

[coach]

Well Cory,
If its really that slim pickings...go with the TA heads. I wanted them but got a great deal on my GN1's

 

[czimpel]

Sounds like a good plan Coach, thanks!