GT40 Aluminium Heads
- Thread starter Chris Liokos
- Start date
Externally, (on the engine) I'm not sure if you can tell them apart, but the part numbers are cast into valve cover area. There will either be a "Y" or "X" along with a three digit number:
FMS-M-6049-X303 is the 64cc head
FMS-M-6049-X305 is the 58cc head
there is also an X304 part number that is sold as a bare head, but I do not know the chamber size.
All heads have 1.94" and 1.54" valves.
Adam
FMS-M-6049-X303 is the 64cc head
FMS-M-6049-X305 is the 58cc head
there is also an X304 part number that is sold as a bare head, but I do not know the chamber size.
All heads have 1.94" and 1.54" valves.
Adam
I have a set of alum tunnel port heads that are stamped "SK"
They seem to be brand new never mounted. I was told "SK" stood for first casting from sketch but I don't know for sure.
They seem to be brand new never mounted. I was told "SK" stood for first casting from sketch but I don't know for sure.
Yes. These are original 427 tunnel port heads.
All,
Ford just came out with the Z304 head it will take 2.02/1.60 valves. There is a write up on them in Muscle mustangs and fast ford's july issue. The article quoted "The ford racing Z304 heads are worth a solid 50 HP over the smaller GT-40X heads. Note that the Z304 heads offered a power improvement across the board, a sure sign the GT40X heads were restricting the 392 crate motor." It also states that they flow 275 CFM as the GT40X flow 240 CFM max.
Ford just came out with the Z304 head it will take 2.02/1.60 valves. There is a write up on them in Muscle mustangs and fast ford's july issue. The article quoted "The ford racing Z304 heads are worth a solid 50 HP over the smaller GT-40X heads. Note that the Z304 heads offered a power improvement across the board, a sure sign the GT40X heads were restricting the 392 crate motor." It also states that they flow 275 CFM as the GT40X flow 240 CFM max.
Ross Nicol
GT40s Supporter
Chris
Lift one of your rocker covers off.The head number is cast in alloy around the valve area. If you have the Ford racing catalogue it is handy for identifying these numbers.
X302 will be cast in the X303 head complete with valves.
Y302 will be cast in the Y303 head complete with valves.
I have the X heads and after I ported them I took them to the machine shop to have the valve seats checked and they found the original valve seats very poorly machined.Considering they are meant to be a bolt on replacement this would make you think again.Hope my info helps feel free to talk to me.
regards Ross
Lift one of your rocker covers off.The head number is cast in alloy around the valve area. If you have the Ford racing catalogue it is handy for identifying these numbers.
X302 will be cast in the X303 head complete with valves.
Y302 will be cast in the Y303 head complete with valves.
I have the X heads and after I ported them I took them to the machine shop to have the valve seats checked and they found the original valve seats very poorly machined.Considering they are meant to be a bolt on replacement this would make you think again.Hope my info helps feel free to talk to me.
regards Ross
Chris,
The X heads flow a bit better than the Y's. They are supposed
to get you 10HP more than the Y's, right out of the box.
Bill
The X heads flow a bit better than the Y's. They are supposed
to get you 10HP more than the Y's, right out of the box.
Bill
Ron Earp
Admin
Check the chamber volume on the Y's, get them milled to give you whatever compresion you want. Have them flowed and ported, three angle valve job, and if they are stock springs CHECK THEM. They had a bunch that didn't have good springs at all. They'll perform well though if you just do a little work upfront. I learned my lesson by bolting them on a motor with no prep, the results were not good. Ended up having to take them off and re-work them, after that things were fine.
Ron
Ron
Jim Rosenthal
Supporter
I agree with Ron on this, although I hasten to add my motor is not finished and running yet. All the sources I could find favored AFR for flow numbers, as well as quality control. Price is about the same. They were also very helpful on the phone about piston recommendations and there is an excellent 'alacarte" menu of options they can fit. Nice guys.
Peter Delaney
GT40s Supporter
I am going to use AFR 165cc Alloy heads P/N AFR 1472 - local expert advice is that they are the best optimum choice for flow vs emissions.
Peter D.
Peter D.
