GT40 head spark plugs

Guero

Active Member

Oct 11, 2005

2,148

0

47

Dec 8, 2008

#1

• Dec 8, 2008

• #1

What kind of spark plugs do GT40 heads use? And what would 2 degrees colder be?

 

legalize420

Active Member

May 21, 2005

1,541

1

37

South Florida

Dec 8, 2008

#2

• Dec 8, 2008

• #2

autolite 764 is stock , 104 is 1, and 103 is 2

 

blksn955.o

Founding Member

Mar 15, 2002

3,263

0

66

st.louis mo 314

Dec 9, 2008

#3

• Dec 9, 2008

• #3

I use NGK's

Stock plug using NGK is a TR5, one step colder is a TR6 and to go 2 steps colder you have to go to an Irrid. plug that is called a TRi7 or TR7i. This is from NGK's tech line

I run the TR6's

 

RydeOn

Licensed to Chill

Founding Member

Sep 26, 2000

6,273

1

77

orange county, CA

Dec 15, 2008

#4

• Dec 15, 2008

• #4

TR6s are wrong. Plug is way too short, sits too high up in the head. Use Autolite #2544.

 

blksn955.o

Founding Member

Mar 15, 2002

3,263

0

66

st.louis mo 314

Dec 15, 2008

#5

• Dec 15, 2008

• #5

That is what I run now and that is what NGK says to run as 1 range colder over stock...stock being a TR55, sorry just checked my paper I have it on and stock is a 55 not a 5. I went to several shops, tech lines, performance shops to double check.

I probably have ran 4-5 different plugs from what people said worked. I am 100% sure tr6 plugs are 1 range colder than stock and stock is a TR55.