Which plugs w/Champion heads?

[wahoo50]

Have early version Champion aluminum heads, been running long reach Champion plugs. Just noticed the AC plugs I used on another engine are short reach.

Anyone know which is correct for these heads?

Ignition breaking up when accelerating hard.

 

[whitehot1]

Have early version Champion aluminum heads, been running long reach Champion plugs. Just noticed the AC plugs I used on another engine are short reach.

Anyone know which is correct for these heads?

Ignition breaking up when accelerating hard.

I bought my Champion GN1 aluminum heads in 2001 and the plugs that was recommended on the instruction sheet that came with them was Autolite 103 and 104 which are long reach plugs.

 

[wahoo50]

Cool, thanks for the reply. So, which plugs do you use?

 

[Major Nutz]

103's work for me.

 

[Nasty Wendy]

AC 43's

 

[whitehot1]

Cool, thanks for the reply. So, which plugs do you use?

I like the NGK plugs TR5,TR6 or their R5724-8 racing plugs.

 

[Sam Colalillo]

For racing:
Autolite 104 or AC Delco R42LTS

for regular street driving
Autolite 103 or R43LTS

The autolite 103 work best for both racing and aggressive street tune in my opinion.