Spark Plug Gap
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Supreme Member
Joined: Jul 1999
Posts: 1,011
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From: Saskatoon, Saskatchewan, Canada
Car: 86 Trans Am
Engine: 406
Transmission: TH350, 4200
Axle/Gears: Moser 9", 3.89
Spark Plug Gap
What do you guys gap your plugs at?
I have ngk plugs and jacobs wires (which say to gap +.010) and I gap at .055
is this too much?
I have ngk plugs and jacobs wires (which say to gap +.010) and I gap at .055
is this too much?
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Joined: Feb 2000
Posts: 1,170
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From: Seattle, Washington
Car: '87 IROC-Z/'82 RX7
Engine: SBC 355/1.1L Rotary
Transmission: T56/5 Speed
Axle/Gears: 4.33/3.93
I thought the Jacobs Ultra Coil tells you to gap +.01, not the wires?
Atleast my ultra coil did.
If that is all you have, and you don't have the coil, I wouldn't gap it anymore than .005 over stock. If stock is .035 for you, maybe gap at .040..... or .045 to .050
If you have the coil and or MSD box with the wires and plugs then .055 would be okay.
I have all that and still only gap at .045
Atleast my ultra coil did.
If that is all you have, and you don't have the coil, I wouldn't gap it anymore than .005 over stock. If stock is .035 for you, maybe gap at .040..... or .045 to .050
If you have the coil and or MSD box with the wires and plugs then .055 would be okay.
I have all that and still only gap at .045
Thread Starter
Supreme Member
Joined: Jul 1999
Posts: 1,011
Likes: 0
From: Saskatoon, Saskatchewan, Canada
Car: 86 Trans Am
Engine: 406
Transmission: TH350, 4200
Axle/Gears: Moser 9", 3.89
I have a jacobs coil too, but the wires were what supposedly allowed the .01 gap increase....
Also, I don't really know what stock is….this is a traditionally SBC I guess...what else has an effect on optimum plug gap?
Also, I don't really know what stock is….this is a traditionally SBC I guess...what else has an effect on optimum plug gap?
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