GT-40 Head Identification

Discussion in 'Classic Mustang Specific Tech' started by 65-Fstbk, Nov 3, 2007.

  1. Hi All,

    A friend of mine had a set of heads he was going to use on a V8 TR6 project that he had to sell unfinished. I got the heads :nice: .

    All I know (through him) is that apparently they're cast alum Ford Motorsports GT-40 heads that came off a HP 302 Slalom car back in the 80's.

    I'm going to use them on my 289 build with the objective being a 300-325HP 289

    I can't find GT-40 anywhere on the heads though but can see Ford Motorsports in the casting. There is also a serial number of some type as well.

    Two questions:

    Anyone know how to identify exactly what I've got here (i.e. what should I look for on the heads)?

    Can the roller rockers be reused? I know the lifters shouldn't be reused but what about the rockers?

  2. No problem on reusing the rockers.

    Post the casting numbers.
  3. post the numers on the heads, any you can find. the should be something that says like M-6903-x302 or something along those lines, if you find that number post it up and we can tell you more about what you have. you should be able to re-use the rockers but they should have number on them as well so post those too if you can find them.
  4. there should be 3 bars on the front of the heads where the accessories bolt on.
  5. I had a look

    here's the info I could see

    The rockers are gold in colour and are stamped
    'Crane 36-160'
    Below that stamp is the symbol of a star and the '-11'

    The casting numbers off the heads appears to be:

    above the casting number is another number that was done post cast which reads 4758.

    Can't see any bars on the front of the heads.

    What do you think?

  6. that's for the P heads, these are older aluminum heads, not applicable.

  7. are you it's not M-6049-J302? if so those are the older standard gt-40 aluminum head, pretty decent head. i think the rockers might be just standard crane rollers, are they gold or silver?
  8. Oh, I skipped over cast "alum" my bad:nono:

    But, GT-40 cast iron heads have 3 bars, GT-40P heads have 4 bars, that's the easiest way to tell the difference between them.
  9. Heads

    Rockers are gold.

    Yeah, I suppose the casting could be M8049, it's kinda hard to tell.

  10. oh yeah, right you are. i was stuck one the aluminum part myself. all good.
  11. Ditto, those are the J302 heads, not GT40's. I think those were their first aftermarket offering in small block heads after they got back into the market in the early 80's.
  12. 300hp should be easy, even with a stock cam and conservative tune. In all my experience (!) just a decent set of heads will get you 300+. Heck, 300 really shouldnt be hard, even with stock heads.
  13. Thanks

    for all the help guys.

    Yeah 300-325HP should be pretty easy. The reason I want to be around that number is to have a fun street toy with reliability (although I won't be using EFI for nostalgia reasons).

    I was going to do the whole wild motor thing but was speaking with a guy up the street from me who's doing a 69 Daytona. He used to run blown alchohol drag cars and was telling me that too wild can be too much in a 2500 lb car without other mods to keep the power under control. He said not to focus so much on the HP but rather a smooth low end torque curve as a good street car needs to perform through the lower RPM's more than they do over 6000.

    Really good guy. He has changed the way I'm thinking about my motor. 325 HP in a 2500 lb car will be plenty of fun I think...especially with the T5.

    Besides, although I'm restomodding my 2+2, the car will wear 289 badges. I think the motor should reflect the badging on the car although it will be a somewhat thirsty 289 :D .
  14. That's good advice for a street's all about bottom end and midrange torque for stop light to stop light fun.