The correct NGK plug # for street use GN-1 heads

[LOT]

as title says--tried search function --no luck--dummy--thanks

 

[DR BOOST]

tr6

 

[turbobuick]

tr6

Aren't the TR6 for iron heads?

If you have the alum GN-1's with a 14mm plug (almost all of them) the NGK plug I always used was a R5671A-10. On the street you will probably want a -9 or even -8 but I would probably start with -9 and see how long it lasts.

 

[V6RACER]

Aren't the TR6 for iron heads?

If you have the alum GN-1's with a 14mm plug (almost all of them) the NGK plug I always used was a R5671A-10. On the street you will probably want a -9 or even -8 but I would probably start with -9 and see how long it lasts.

9s and 10s are pretty cold.. and those are recessed tips you may want standard tip on street car.

 

[DR BOOST]

Aren't the TR6 for iron heads?

If you have the alum GN-1's with a 14mm plug (almost all of them) the NGK plug I always used was a R5671A-10. On the street you will probably want a -9 or even -8 but I would probably start with -9 and see how long it lasts.

a ur6 is for stock heads.

the r5671A-7 works well on my car . this is for street use

 

[LOT]

heads

these heads are 8-10 years old with the 3 extra holes @ the bottom.

 

[turbobuick]

a ur6 is for stock heads.

the r5671A-7 works well on my car . this is for street use

That is probably a pretty good street plug. I never used the TR6's but then again my "street" cars tend to be a little on the aggressive side

How would an extended or recessed tip make a big difference on a street driven setup? Are the recessed more prone to fouling? Just curious, I figured it would be mostly heat range.

 

[lazaris]

That is probably a pretty good street plug. I never used the TR6's but then again my "street" cars tend to be a little on the aggressive side

How would an extended or recessed tip make a big difference on a street driven setup? Are the recessed more prone to fouling? Just curious, I figured it would be mostly heat range.

Projected tip plugs moves the spark gap further into the chamber. This improves efficiency by shortening the distance traveled by the flame front. This also acts to change the effective timing requirement.
It also comes up to temperature faster for cleaner burning.
The down sides to the projected tipped plugs especially in a boosted or higher HP application is that by being more exposed to the flame front, the spark tends to be more easily blown out. The recessed plug is more shielded, protecting it some from being blown out.
They also tend be more detonation prone in a high HP applications and can act like a glow plug.
They also reduce piston to plug clearance in high compression applications.
Theres more but you get the picture.

 

[turbobuick]

Nice explanation, I figured the recessed tip would be more prone to fouling but I cant remember the last time I actually ran a projected tip plug even on the street. But then again I change plugs so frequently I always run a pretty cold plug even on the street.

FYI cross referencing heat ranges between plug manufacturers is not an exact science and the reference charts differ from one manufacturer to another. The 12mm plug GN1 heads only option is the Autolite AR4132, NGK does not have a comparable plug to the 14mm 5671's for a 12mm application.

 

[LOT]

heads

Are @ the machine shop--I just got off the phone with them. He said these heads take a plug with a sealing ring--also 14 mm thread. Now what do I need?

 

[forcefed3.8's]

NGK TR6, Autolite 103, AC r42lts all work. The NGK's and AC's take the tight better.
I was running a set of NGK non resistor racing plugs heat range 8 (#7317 I think), and they fouled withing 100 miles running Q16. I am running TR5 now, which are kind of hot, but I drive like an old lady, I will put the colder ones in at the track.