GN 1 Aluminum heads, recommended spark plugs (22-24 psi)

[Ed Valvo]

Looks like the GN1's will accept both types of plugs. New and old version castings.

 

[larry33kc]

Does any have any idea why mine has the 4132s in it then? And what are the difference between the two?

 

[troyk]

I have 103 plugs in now & I am wondering if a gasketed plug is better to have in the heads, better seal? I've seen other posts talking about a 4133 plug, but that is 12mm & it is a newer head & that the 12mm was help with head cracking problems. I see above that AR3935 has a longer reach, but non-projected & non-resistor. Is there a resistor & gasketed plug for me to use? I have plans to run 93 or E85 w flex sensor. I also, have IGN-1As. Or should I just stay w ungasketed, if we are worried about head cracking? I know my heads are not the 1st gen heads, because I had bought newer ones, that were supposed to be more crack resistant, but which gen, I don't know. It does have more metal along the bottom edge of the head, when bolted on the motor.

 

[grass doctor]

if you want the best .. look into briskracing plugs

 

[grass doctor]

this thread might help even though its for TA heads... but they are very similar

https://www.turbobuick.com/threads/spark-plugs-for-ta-heads-and-tr6.464327/

 

[BEATAV8]

I have 103 plugs in now & I am wondering if a gasketed plug is better to have in the heads, better seal? I've seen other posts talking about a 4133 plug, but that is 12mm & it is a newer head & that the 12mm was help with head cracking problems. I see above that AR3935 has a longer reach, but non-projected & non-resistor. Is there a resistor & gasketed plug for me to use? I have plans to run 93 or E85 w flex sensor. I also, have IGN-1As. Or should I just stay w ungasketed, if we are worried about head cracking? I know my heads are not the 1st gen heads, because I had bought newer ones, that were supposed to be more crack resistant, but which gen, I don't know. It does have more metal along the bottom edge of the head, when bolted on the motor.

Gasketed plugs are much easier on the threads in the head.
NGK BCR8ES (5430) is an excellent plug. Buy off eBay from Great Britain. Gasketed, resistor, non projected.
Brisk DR10S or DR12S from Jegs or Summit. Also gasketed, resistor, non projected. More heat ranges too. But pricey...