What Heads do I have?

[Jekyl]

I bought Autolite 25s to do change my spark plugs and they wont fit in. Someone told me becuase my heads probly arent stock. The sparkplugs that I pulled out of the car are called NGK TR55-1 V-Power. This picture shows the difference Between the Autolite 25s that wont fit and the NGKs that were in my car. Also My angine block and heads are painted navy blue... is that stock? What heads do I have??

Autolite 25s on the LEFT and NGK TR55-1 on the RIGHT

 

[TomCat]

Wow, did those NGKs thread down all the way?? Look for casting marks all over the heads... just anyway to identify it. The stock e7te heads don't have any openly visible ones.

 

[Jekyl]

Subscribing...

 

[Jekyl]

BUMP BUMP!!!! Sorry for double post but its been like 6 hours with no reply.

 

[88 Fox GT]

Take some pictures of these heads.

I thought that even aftermarket aluminum heads and such used the stock specs for spark plugs.
Odd.

 

[tony91723]

I know my AFR's take a longer spark plug similar to the NGK pictured. I think the number is autolite 3924 or 3923 I can't remember off the top of my head. I would recommend like others, look around and maybe take the valve covers off to check and look for casting numbers.

 

[ratrapp]

you probably have e-5 or e-6 heads.i ran into the same problem a couple of years ago.they take a different plug.

 

[MrKwik]

The motor I had in my 89GT was out of a 93 cobra and had the cast iron GT40 heads on it. Took long ass plugs just like that.

 

[jbj454]

I have aluminum GT40 Heads and they take a longer plug. They called for some weird name that cross referenced to a Autolite 104 plug that was long like that. Call the parts store and get them to cross reference that number for you