Auto lite 3924 doesn't fit?

OonDeanisS

Founding Member

Jun 16, 2002

902

1

19

Danbury, CT

Feb 19, 2012

#1

• Feb 19, 2012

• #1

I have gt40 iron heads, and I bought auto lite 3924s but they don't thread in... They look identical to my old plugs but these won't thread into the hole... I don't get it. Do I need to cut off the aluminum washers or something? The old ones thread in and out fine, but those are NGK platinums. Any help appreciated. Also, gap to .030?

 

Chuckman

GTFO you fat, heavy bastard

15 Year Member

Oct 21, 2005

1,604

1,002

173

st. louis, mo

Feb 19, 2012

#2

• Feb 19, 2012

• #2

i dont know what the plain gt-40's use, but the gt-40p's use a 764 plug. looking it up on the az site, the plains use them too.

 

Rick 91GT

Mustang Master

Nov 29, 1999

9,692

95

99

PA

Feb 19, 2012

#3

• Feb 19, 2012

• #3

Yes 764 is the correct plug, which is a tapered seat plug (NO WASHER) The 3924 are extended reach with the washer, you would use these on a alum head.

Gap to .035" if you have boost, .045"-.053" if your NA

 

OonDeanisS

Founding Member

Jun 16, 2002

902

1

19

Danbury, CT

Feb 19, 2012

#4

• Feb 19, 2012

• #4

thank you.