Do GN1 Aluminum heads use the same spark plugs as stock heads?

[ttribejr]

Thanks.

 

[TurboTnZ06]

I don't think so, I have Autolite 103's in my alum heads.

 

[Boost231]

No, different plug

Sent from my SM-G935T using Tapatalk

 

[RUQWKNF]

They definitely use a different plug, than what is typically used in the cast iron 8445 heads. I also used Autolite 103's, as well as their race spec plug. The 103's worked great on street boost levels under 25psi on my Stage II with GN1 aluminum heads. I used race plugs at the track when boost levels got interesting. I will have to dig up and old plug for the race plug p/n and report back.

 

[vacuum 6]

Different plug. My engine like the autolite 104s vs 103s.

 

[pacecarta]

iron head uses short reach (1/2" of thread) tapered seat plug .
gn1 alums need long reach (3/4" of thread) plugs and they can be taper seat or ring seat style ..
most use the autolite 103 but thats a projected tip taper seat .. i run the AR3934 -AR3933 colder - AR3932 colder which is a non projected tip , cut back electrode and ring seat
newer gn1 aluminum heads use 10mm thread plugs

 

[bad V6]

I run NGK 4554

 

[whitehot1]

No,they don't use the same spark plugs as the stock Buick GN heads.

But they do use the same spark plugs as the stock 1989 Pontiac Turbo Trans Am.

When i call the local auto parts stores i tell them that's what they are for or when looking them up on Rockauto that's what application i look them up for.

 

[pacecarta]

TTA used the R42LTS

 

[ttribejr]

Well shoot. I just got them a few months ago. Was going to order spark plugs today. Wonder what threads they are. Im at work and guessing every vendor is closed today.

 

[whitehot1]

Well shoot. I just got them a few months ago. Was going to order spark plugs today. Wonder what threads they are. Im at work and guessing every vendor is closed today.

Here you can find the specs for the Autolite 103 spark plugs from sparkplugs.com web site.

https://www.sparkplugs.com/product.aspx?zpid=20339

 

[ttribejr]

Says they are 14mm. somebody said the new heads are 10mm? i need to confirm.

 

[pacecarta]

Says they are 14mm. somebody said the new heads are 10mm? i need to confirm.

well what did you pull out ??

 

[ttribejr]

well what did you pull out ??

Its a brand new build. trying to get the last few things i need to install the motor and get her running.

 

[pacecarta]

dont know what to tell you ..look in the (your) spark plug hole and see what it takes btut if you cant tell a 10mm hole from a 14mm then try a 14mm and if its fits its not a 10mm

 

[whitehot1]

Here is an adapter that's used to go from a 14mm to a 10mm spark plug.
It should be easy to tell just by looking at the spark plug hole what size spark plugs you are going to need.

https://www.valleyviewrc.com/14mm-10mm-spark-plug-adapter

 

[ttribejr]

I went and checked them on my lunch break. My 3 month old GN1 heads have 14mm thread spark plug holes.

 

[ttribejr]

Different plug. My engine like the autolite 104s vs 103s.

what did you notice about the 104 vs the 103s? How did it like it better?

My stock longblock @ 35psi on e85 ran best with stock heat range plugs too. no knock. I tried colder plugs and it ran noticeably rougher and I fouled a couple of them in short time.

 

[whitehot1]

I went and checked them on my lunch break. My 3 month old GN1 heads have 14mm thread spark plug holes.

That makes it easy for finding spark plugs. I know Advance auto parts use to have them in stock for the Autolite racing spark plugs and they may still do. And the Autolite 104 spark plugs can be bought at just about any auto parts store local to you.

 

[vacuum 6]

Different plug. My engine like the autolite 104s vs 103s.

what did you notice about the 104 vs the 103s? How did it like it better?

My stock longblock @ 35psi on e85 ran best with stock heat range plugs too. no knock. I tried colder plugs and it ran noticeably rougher and I fouled a couple of them in short time.

Other than different day ambient temps were similar no other changes...pickup 5 mph.