Which GT40 heads?

[dw89lx]

Does anyone know how to tell which gt40 heads I have? Is there any markings that are visible on the outside of the heads. I bought the car with the heads already on. I went to change the spark plugs and found that the last guy that owned the car used Bosche 4449 plugs which are used on the stock heads. I was told that I should be using autolite 3924's. Now I'm wondering if the heads are even GT40's.

 

[bjl95mustang]

They will have gt cast on them. you should beable to see it near the lower head bolt on the front of the head.

 

[Insane3D]

Does anyone know how to tell which gt40 heads I have? Is there any markings that are visible on the outside of the heads. I bought the car with the heads already on. I went to change the spark plugs and found that the last guy that owned the car used Bosche 4449 plugs which are used on the stock heads. I was told that I should be using autolite 3924's. Now I'm wondering if the heads are even GT40's.

Are they aluminum or cast iron?

 

[dw89lx]

The heads are supposed to be aluminum but kinda look like iron to me. The guy that I bought the car from told me that the heads are aluminum. The only castings that I could find on the outside was a number 17.

 

[Insane3D]

I think all the aluminum GT40 heads, both X and Y variants have a "SVO" stamped in the front and back of the heads.

 

[jasonlee0704]

Collected from 2 different sources, Mustang Performance Engine Tuning and the Mustang 5.0 Technical Reference, here's how to distinguish between GT-40 castings.

OEM iron GT40 head:

has 3 vertical ribs cast into each end of the head
have "GT" cast into the right outboard corner

OEM iron GT40P head:

has 4 vertical ribs cast into the front of the head
has "GTP" cast into the head

SVO/FRPP aluminum GT40Y and GT40X head:

have "SVO" logo cast into the front of the head

 

[Insane3D]

Collected from 2 different sources, Mustang Performance Engine Tuning and the Mustang 5.0 Technical Reference, here's how to distinguish between GT-40 castings.

OEM iron GT40 head:

has 3 vertical ribs cast into each end of the head
have "GT" cast into the right outboard corner

OEM iron GT40P head:

has 4 vertical ribs cast into the front of the head
has "GTP" cast into the head

SVO/FRPP aluminum GT40Y and GT40X head:

have "SVO" logo cast into the front of the head

Just to add to that, my GT40 X305's have the SVO logo stamped on the front and back of the head.

 

[dw89lx]

Well it looks like I got screwed!!! I wish I knew about the castings before I decided to buy the car. Where there any older gt40 heads without the lines or gt cast into the head?

 

[Insane3D]

Well it looks like I got screwed!!! I wish I knew about the castings before I decided to buy the car. Where there any older gt40 heads without the lines or gt cast into the head?

I don't believe so...sorry.