How to identify GT40x heads??
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Right on the front of the head it says SVO in big letters. Like Kurt said the X series are aluminum so the color of the heads will be lighter than cast iron. Look where the accessory brackets bolt to the heads, if they are X you'll see the SVO stamp. All the other stamps will not be visible without taking the valve covers off.
If you are not good at distinguishing colors, or the heads are painted or dirty, just do the magnet test to see if they are aluminum.
Kurt
Kurt
Thanks guys, revhead347 the magnet test you mention. Are you saying to place magnet on an exposed area of the head and the magnet should stick? The heads are a really light in color, but I tried to stick a magnet on a small exposed area and the magnet did not stick. The heads are on the car with everything bolted up so I could not see the markings you spoke of VibrantRed.
That's a good start, that means they are aluminum. Now you can start looking for markings. See if you can get a mirror in behind the head. Like someone else said, they should say SVO in big letters on the back.
Kurt
If they are aluminum, you can pretty safely assume that it has the GT-40x heads like you were told. That's something most people wouldn't lie about. All those entry level aluminum heads cost about the same, and the GT-40x is arguably the lowest performer of those heads. Not by much, but enough that there is no incentive to lie about it.
Kurt
Kurt
Sounds good. Unfortunately it's hard to tell what kind of cam there is without taking it out.
Kurt
Kurt
There should be casting numbers where the rockers go. Tell us what the numbers are. I think "X303" and "X305" heads differentiate between stud and pedestal mount heads and/or combustion chamber size.
Yes , X-303 are 64cc chamber and X-305 are 58cc chamber . Both are pedestal mouting rockers and have 1.94" int./1.54" exh. valves . Here are Ford Racing flows numbers:
I bought my GT40X heads bare and upgraded the springs to Steeda Hi-Rev's and valves to Ferrea's. I should have had all the ports cleaned up. Lots of cast flash. When I upgraded to the 347 I went with AFR 185's so they were sold. They sat in Rogers (Green94 5.0) garage for like 7 years. They got dusted off a few months ago. They are now on his 1992 GT with Vortech V3i and my old Edelbrock RPM Polished Intake / 70MM throttle body. So 12 years later they are still going strong.
Here they are.
Here they are.
Good stuff, Advent. Thanks! I think that should pretty much hit the nail on the head as far as what the OP was looking for.
