GT 40 Heads Question

[crunchie12268]

Okay when I bought my car the guy said that it had GT40's, all I can see is they are painted orange, but is there any way to verify this? Also, I really need to know the kind of spark plugs these things use. Can I just say I need the plugs for a 93 Cobra? Don't they have the GT40's?

 

[Rick 91GT]

They should say GT right near the front of the head near the spark plug hole, head bolt hole below the valve cover rail.

Yes the 93 Cobra had the cast iron GT-40's you could ask for them with no issues at all.

 

[Michael Yount]

Another way to check too - look on the ends of the heads where the accessory brackets bolt up -- there will be 3 parallel bars cast into it. 4 parallel bars indicate GT40-P's.

 

[crunchie12268]

It says GT on the front so thats good. It also has the bars so thats good... I am using the NGK TR55 and that is what the cobras use so the plugs are the rights ones. I checked my plugs, and they have about 3000 miles on them and they are a little tanish yellow like on the ends, then there is a little green, and also on the bottom of the tip there is some green... what does that mean... good? I also have an MSD 6AL and Blaster 2 Coil, the gap is at about .045.... is that good for a high output igintion?

 

[Ourobos]

That all sounds good. Make sure you don't TRY the bosche platinums with those heads.. (Sux0rs)

 

[Michael Yount]

With the higher powered ignition, set the gap as large as you can with it still running good. Stock is .054 -- you ought to be running AT LEAST that much with the MSD. I'd set 'em at .060" and see how it runs. As long as the igntion system can manage the gap - the bigger the gap, the bigger the spark and the more of it that is exposed to combustible mixture.

 

[crunchie12268]

thats what I thought, and thats why I asked, in my manual it said .044, then the plugs were .054 out of the box. Could this be dampening my performance?

 

[Michael Yount]

I doubt it'll make a BIG difference if that's what you're looking for. But the big energy ignitions are there so you can make a big fat spark jump a bigger gap. Open those puppies up to about .060" and see what happens.

 

[crunchie12268]

I doubt it'll make a BIG difference if that's what you're looking for. But the big energy ignitions are there so you can make a big fat spark jump a bigger gap. Open those puppies up to about .060" and see what happens.

Im on my way

 

[Matts89LX5.0]

They should say GT right near the front of the head near the spark plug hole, head bolt hole below the valve cover rail.

Yes the 93 Cobra had the cast iron GT-40's you could ask for them with no issues at all.

I thought the 93 cobra came with GT-40 Ps?????? if not which cars came with the P's?? thanks

 

[Michael Yount]

No Matt - 93-95 Cobras all came with cast iron GT40's. Only the Explorers and Mountaineers of later production came with the GT40P's. The head was changed as emissions regs even for the trucks became tighter - the P's combustion chamber burns more efficiently and cleaner than the 40's.

 

[Matts89LX5.0]

thanks michael--you da man!!!