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Spark plug gapping

JerzNick

JerzNick

SE Level Member
Ok guys, Got the xp cam in, Heads just came back from the machine shop so it's time to put her back together.

I got Autolite 103's but I don't know what to gap them?!

Any help please.

Thanks in advance.
 


Stock Ported S/C, Ported Lim & Heads

3.4 Pully, Might drop to 3.25

Is there a formula for figuring this out? or pure experience?
 
SlowNA06 said:
Your 103's are too cold. Use Autolite 104's gapped to 0.060".
Click to expand...

Thanks for your input. What makes you say they are too cold? I was told by a few members to use 103's... I'm just curious as to how you feel 104's would run hotter?

Thanks
 


I've put Use Autolite 104's gapped to 0.060" on a 3.4" GenV setup running more boost than yours (more restricted exhaust) and had no knock or "spark blowout" issues. Anyone telling you to gap smaller probably hasn't actually experienced spark blowout and is just parroting something they heard. As for the plugs - ALWAYS start with the hottest plug you can, scan for knock, then go a single step colder as needed. The most common spark plug used in 3.4" pulley setups is only two heat ranges colder than stock; the AL104.
 


Here...from my thread:

Spark Plugs - Change out those stock spark plugs with new ones to restore any lost power. Brands that most tend to go with are either Copper Core Autolites or NGK's. They range as follows in order from hottest to coldest plugs...remember...you want the hottest spark you can get away with...so running a super cold plug on a larger pulley to combat knock isn't the best plan...OEM replacement ACDelco's, AL606's, and AL605's are basically for stock cars or very small bolt-ons still running the stock S/C Pulley or modded N/A guys...you want to keep a hot spark. NGKTR55/AL104's for your 3.4" Setup, TR6's are a tad cooler...best used around the 3.25" pulley area, and AL103's...are for the extreme supercharged application...3.0" pulley or lower. Here is a picture to reference the firing order and the correct coil number if yours aren't numbered or you just need a quick reference picture: http://i33.photobucket.com/albums/d6.../plugwires.jpg

AC Delco Factory Replacements: Stock
Autolite 606: Stock
Autolite 605: 1 Heat Range Cooler
NGK TR55: 1 Heat Range Cooler
Autolite 104: 2 Heat Ranges Cooler
NGK TR6: 2 Heat Ranges Cooler
Autolite 103: 3 Heat Ranges Cooler
Click to expand...
 


NGK Spark Plugs USA

2000 PONTIAC GRAND PRIX GTP 3.8 V6 1 FI Supercharged​
[TABLE="width: 95%"]
[TR]
[TD="bgcolor: #222222"]Spark Plug
[/TD]
[TD="bgcolor: #222222"]Part No.[/TD]
[TD="bgcolor: #222222"]
Stock No.​
[/TD]
[TD="bgcolor: #222222"]
Plug Gap​
[/TD]
[TD="bgcolor: #222222"]
Photo​
[/TD]
[/TR]
[TR]
[TD="bgcolor: #FFFFFF"]V-Power[/TD]
[TD="bgcolor: #FFFFFF"]TR55[/TD]
[TD="bgcolor: #FFFFFF"]
3951​
[/TD]
[TD="bgcolor: #FFFFFF"]
.060​
[/TD]
[TD="bgcolor: #FFFFFF"]
camera.gif
[/TD]
[/TR]
[TR]
[TD="bgcolor: #FFFFFF"]G-Power[/TD]
[TD="bgcolor: #FFFFFF"]TR55GP[/TD]
[TD="bgcolor: #FFFFFF"]
3403​
[/TD]
[TD="bgcolor: #FFFFFF"]
.060​
[/TD]
[TD="bgcolor: #FFFFFF"]
camera.gif
[/TD]
[/TR]
[TR]
[TD="bgcolor: #FFFFFF"]Laser Platinum[/TD]
[TD="bgcolor: #FFFFFF"]PTR4B-15 * #[/TD]
[TD="bgcolor: #FFFFFF"]
5146​
[/TD]
[TD="bgcolor: #FFFFFF"]
.060​
[/TD]
[TD="bgcolor: #FFFFFF"]
camera.gif
[/TD]
[/TR]
[TR]
[TD="bgcolor: #FFFFFF"]OE Laser Iridium[/TD]
[TD="bgcolor: #FFFFFF"]ITR4A15 ^[/TD]
[TD="bgcolor: #FFFFFF"]
5599​
[/TD]
[TD="bgcolor: #FFFFFF"]
.060​
[/TD]
[TD="bgcolor: #FFFFFF"]
camera.gif
[/TD]
[/TR]
[TR]
[TD="bgcolor: #FFFFFF"]Iridium IX[/TD]
[TD="bgcolor: #FFFFFF"]TR55IX[/TD]
[TD="bgcolor: #FFFFFF"]
7164​
[/TD]
[TD="bgcolor: #FFFFFF"]
.060​
[/TD]
[TD="bgcolor: #FFFFFF"]
camera.gif
[/TD]
[/TR]
[/TABLE]
Click to expand...
 
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