GT-40 head plug gap? February 02, 2007, 09:19:19 PM Ok so as you know I'm dropping in a GT-40 iron headed 5.0 HO in my Bird in about 6 weeks. I just bought Autolite plugs and since they're new I need to gap 'em. I'm guessing that a car with GT-40 heads (ie 93-95 Cobras) had the gap set at about 054 right? I'm just making sure. Thanks:D Quote Selected
GT-40 head plug gap? Reply #1 – February 02, 2007, 10:56:42 PM first off what GT40 heads do you have the old school ones or the GT40p heads?the reason why i ask is for the plug style they will either 25's which in my opinion you should go one heat range colder which is 24's or if they are older heads they use 2924's both should be gaped at around .044 to.046 for an N/A motor and about.034 to .036 for a supercharged or turbo motor. forget what the books say about .054. trust me it will run much better.. if you like to tinker around you can test this theory to see if i'm right.just make sure you get the right style plugs for the heads .. or you will be very dissapointed..Nick Quote Selected
GT-40 head plug gap? Reply #2 – February 02, 2007, 11:02:50 PM .045 is what i set all my TFI ignition plugs on except turbo and supercharged motors. Quote Selected
GT-40 head plug gap? Reply #3 – February 03, 2007, 07:37:22 AM Hell i set mine at .29thou with my supercharger,wanted to make sure not to blow out the candles.But right around .44-.46 is right for an N/A combo. Quote Selected
GT-40 head plug gap? Reply #4 – February 03, 2007, 04:33:40 PM Quote from: Blown306Cougar;127326first off what GT40 heads do you have the old school ones or the GT40p heads?the reason why i ask is for the plug style they will either 25's which in my opinion you should go one heat range colder which is 24's or if they are older heads they use 2924's both should be gaped at around .044 to.046 for an N/A motor and about.034 to .036 for a supercharged or turbo motor. forget what the books say about .054. trust me it will run much better.. if you like to tinker around you can test this theory to see if i'm right.just make sure you get the right style plugs for the heads .. or you will be very dissapointed..NickGT-40 iron heads not GT-40P:D . They are from a 93 Cobra. Like you guys said I'll gap 'em at .044 to.046 and see how it runs. If I have to go with a higher gap (I doubt it) it's not hard to pull the plugs and change them. Quote Selected
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