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Discussion Starter #1
What plugs should I use with a iron headed 302? Right now, I'm running the autolite AR3923 plugs up to a 150 shot. What do you suggest for say 200 shot of gas or higher? Thanks!!
 

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Discussion Starter #4
Are you sure on that plug #. I don't know of a iron head for a SBF that uses a .750 reach, gasket seated plug. What heads?
It is the correct plug number I know. They are tfs high port iron heads from back in the day.:)
The 3923 plugs run well on the motor and with a small shot, but if I step it up to say 175-250 shot, what would be the best plug to use? Compression is around 10.5-1 to 11-1. Thanks..
 

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I'd look at running the NKG R5671A -8's up to a 150 shot....-9's over that..maybe even a -10 depending on how big you go on the spray.


TFS, Edelbrock, and AFR Heads:
[14mm, 3/4" Reach, 5/8" Hex, gasket seat]
AUTOLITE
1 step colder--3924 (4) [*recommended starting point]
2 step colder--3923 (3)
-----AR3933 (3) [*recessed tip, racing plug]
-----AR3932 (2) [*recessed tip, racing plug]
-----AR3931 (1) [*recessed tip, racing plug]

NGK
1 step colder--(FR5) 3686 (5) [*recommended starting point]
2 step colder--(BKR6EY) 3696 (6)
-----(R5671A-8) 4554 (8) [*recessed tip, racing plug]
-----(R5671A-9) 5238 (9) [*recessed tip, racing plug]
-----(R5671A-10) 5820 (10) [*recessed tip, racing plug]

MOTORCRAFT
1 step colder--AWSF22C
2 step colder--AWSF32C
 
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