Finding GT40 heads, but are they worth the trade from 58cc chamber to 64 ?

Discussion in 'General Maverick/Comet' started by stumanchu, Sep 14, 2016.

  1. Krazy Comet

    Krazy Comet Tom

    Joined:
    Sep 13, 2012
    Messages:
    7,560
    Likes Received:
    2,319
    Trophy Points:
    531
    Garage:
    1
    Location:
    Chesapeake VA
    Vehicle:
    1972 Comet GT clone 306 . 1969 Fairlane Cobra 428CJ 1988 T-Bird awaiting 331 ..
    GT-40 heads are basically late versions of the much coveted(at least 40-45 years ago) '69-'71 351W heads. Before modern aluminum heads, were the hot setup for a 302 in the '70s & early '80s.
     
  2. 71gold

    71gold Frank Cooper Supporting Member

    Joined:
    Apr 9, 2002
    Messages:
    26,456
    Likes Received:
    2,834
    Trophy Points:
    978
    Garage:
    1
    Location:
    MACON,GA.
    Vehicle:
    '73 Grabber
    my opinion...if you don't turn it at least 6K there will be no difference than they were stock...JMO
     
  3. Krazy Comet

    Krazy Comet Tom

    Joined:
    Sep 13, 2012
    Messages:
    7,560
    Likes Received:
    2,319
    Trophy Points:
    531
    Garage:
    1
    Location:
    Chesapeake VA
    Vehicle:
    1972 Comet GT clone 306 . 1969 Fairlane Cobra 428CJ 1988 T-Bird awaiting 331 ..
    What is it Frank, like to show just how much you don't know about head flow?

    Improving air flow through the head will usually make noticable difference from 2500 probably through 6000 RPMs(assuming cam hasn't given up). Stock small block are dead past 5200 or so.
     
    hollisj likes this.
  4. 71gold

    71gold Frank Cooper Supporting Member

    Joined:
    Apr 9, 2002
    Messages:
    26,456
    Likes Received:
    2,834
    Trophy Points:
    978
    Garage:
    1
    Location:
    MACON,GA.
    Vehicle:
    '73 Grabber
    he said he wanted power below...2K
    "I think I should avoid anything that begins making power above 2000"
     
  5. Krazy Comet

    Krazy Comet Tom

    Joined:
    Sep 13, 2012
    Messages:
    7,560
    Likes Received:
    2,319
    Trophy Points:
    531
    Garage:
    1
    Location:
    Chesapeake VA
    Vehicle:
    1972 Comet GT clone 306 . 1969 Fairlane Cobra 428CJ 1988 T-Bird awaiting 331 ..
    AND the GT-40 WILL make at least the power of the stock head, probably more.
     
  6. stumanchu

    stumanchu Stuart

    Joined:
    Feb 2, 2016
    Messages:
    1,375
    Likes Received:
    556
    Trophy Points:
    338
    Garage:
    1
    Location:
    Portland, OR
    Vehicle:
    74 comet, 70 Olsen step van, 2005 Scion xB
    I did say that. That XE262 cam is supposed to have a range of 1300-5600. It is the last one they say you can get away with using a stock converter. I have come to realize that I lack the nerve to push my motor passed 6K even if it wanted to. So, its gotta get it done sooner.....and start sooner than 2K. I am hoping for better mpg and cleaner emissions than what I have now.....but I will buy the cam last as I want to tear my motor down enough to see what cam I have before a final decision.
    Yes, it will be state of the art of 1980! but it will feel like the car I always wanted in high school but didnt and shouldnt of had back then.
     
  7. Krazy Comet

    Krazy Comet Tom

    Joined:
    Sep 13, 2012
    Messages:
    7,560
    Likes Received:
    2,319
    Trophy Points:
    531
    Garage:
    1
    Location:
    Chesapeake VA
    Vehicle:
    1972 Comet GT clone 306 . 1969 Fairlane Cobra 428CJ 1988 T-Bird awaiting 331 ..
    That XE262 cam has approx same specs as the stage-1 Trick Flow(yes the TF cam is roller). In my 5.0 T-Bird with Trick Flow heads, it hated the stock converter, a 2K was better and a 2600 better still(still had occasional low speed buck & that was with 3.73 gears). I always felt a 3200 would be about right. Original plan was a swap to 331 using same heads & cam, plus I picked up a rebuilt AOD with a 3500 stall. Since I was using lockup converter cruise speed not affected.

    Now the Fairlane has come on scene, plans are evolving and assuming they are carried out, the 331 will go into Comet. Still deciding on cam, about 90% it won't run the stage-1. The 306 now in car has a mild Lunati VooDoo cam & C4 with a Hughes 2000-2200 stall converter. Has a 3.00 gear & 255/65/15, cruises nice.

    https://www.summitracing.com/parts/...kmRaiqs9pU5VsMpPuc_c1_8-LmJFbCVRoCP-UQAvD_BwE
     
    Last edited: Jul 24, 2019
  8. greasemonkey

    greasemonkey Burnin corn

    Joined:
    Aug 3, 2005
    Messages:
    2,401
    Likes Received:
    203
    Trophy Points:
    208
    Garage:
    1
    Location:
    Sedalia,MO
    Vehicle:
    1973 ford maverick Grabber,2017 dodge ram,88t-bird,indian scout,Indian Chieftain.95 Mustang GT
    Just my take on what your looking for..just find an explorer pullout longblock. Add carb and intake with short tube headers. Update the valvesprings and use 1.7 roller rockers. That will do exactly what you described. It will also yield more power and fuel economy than what your building and be more cost effective.
     
  9. stumanchu

    stumanchu Stuart

    Joined:
    Feb 2, 2016
    Messages:
    1,375
    Likes Received:
    556
    Trophy Points:
    338
    Garage:
    1
    Location:
    Portland, OR
    Vehicle:
    74 comet, 70 Olsen step van, 2005 Scion xB
    That is the other route I was debating, but I figured a cam change would need to be done and I didnt consider the 1.7 rocker possibility. I will have to rethink this a bit more. The rockers would cost less than a cam change.
     
  10. stumanchu

    stumanchu Stuart

    Joined:
    Feb 2, 2016
    Messages:
    1,375
    Likes Received:
    556
    Trophy Points:
    338
    Garage:
    1
    Location:
    Portland, OR
    Vehicle:
    74 comet, 70 Olsen step van, 2005 Scion xB
    I dont want any lugging, that is for sure. I looked briefly at summit and couldnt find that roller cam, but will look again tonight.
     
  11. stumanchu

    stumanchu Stuart

    Joined:
    Feb 2, 2016
    Messages:
    1,375
    Likes Received:
    556
    Trophy Points:
    338
    Garage:
    1
    Location:
    Portland, OR
    Vehicle:
    74 comet, 70 Olsen step van, 2005 Scion xB
    Tom, what was the compression ratio in that motor? I could not find a Ford summit cam, but I did compare the roller cams with identical duration to that XE262 and all of them started making power at 1800 instead of 1300, and the upper limit was 5800 instead of 5600. I imagine there are other factors that create a "power band" other than duration and intake closing timing, gas velocities, port sizes, blah-blah. Learning this stuff is fascinating in its own right.

    My oldest brother had a 327 in the early '70s that was in a 57 vette. I think it had about 11.5:1 . It had various things done to it, and I did get to drive it once. That thing lugged and bucked, and my brother chastised me for shifting too soon. I could barely drive it as I never had a stick shift in any of my cars.....so I didnt get on it at all,lol. that thing sits in a shop in AZ right now, and still has the factory drum brakes....good for most of one hard stop. The thing hasnt run in years, and its best in the 1/4 was 14 flat at 101. It had street radials and major traction issues that kept axles from breaking. someday I will torture him with a sub 14 timeslip from a Ford, heheheheh. Maybe I will go down there for a month and goad him into making it run again.
     
  12. Krazy Comet

    Krazy Comet Tom

    Joined:
    Sep 13, 2012
    Messages:
    7,560
    Likes Received:
    2,319
    Trophy Points:
    531
    Garage:
    1
    Location:
    Chesapeake VA
    Vehicle:
    1972 Comet GT clone 306 . 1969 Fairlane Cobra 428CJ 1988 T-Bird awaiting 331 ..
    I don't know exactly but approx 10:1, pistons were flat top with no valve reliefs.

    The SUM-3600 isn't a bad cam for mild street. Eons ago this same spec cam was in the Ford Racing catalog.

    https://www.summitracing.com/parts/sum-3600/overview/make/ford
     
  13. jasonwthompson

    jasonwthompson Member

    Joined:
    Mar 25, 2012
    Messages:
    1,327
    Likes Received:
    450
    Trophy Points:
    196
    Location:
    Carrollton TX
    Vehicle:
    72 Comet
    I second greasemonkey. I pulled a e7te 5.0 roller short block, used the factory roller h.o. cam with mildly ported early 351w heads, larger valves and springs, and 1.7 rockers with roller tips. The compression is around 10:1 with after market flat top pistons and heads cc'd to 58. Retarded the cam 2 degrees, it will keep pulling past 5K although I don't like to push it much past that. If you want more low end put the factory cam in straight up or possible slightly advanced. The transmission was reworked but the stall speed is the same and the rear end is the factory 8 with 3.00s. The intake is an older Weiand Stealth dual plane which looks nearly identical to the Summit one posted. Still running stock exhaust manifolds at the moment. So far with this budget combo, it is quite lively in the little Comet.
     
    stumanchu likes this.
  14. stumanchu

    stumanchu Stuart

    Joined:
    Feb 2, 2016
    Messages:
    1,375
    Likes Received:
    556
    Trophy Points:
    338
    Garage:
    1
    Location:
    Portland, OR
    Vehicle:
    74 comet, 70 Olsen step van, 2005 Scion xB
    You know, I have looked at these manifolds as much as one can through a laptop......and I think you are right. The stage 2 manifold is more like a performer RPM or a Stealth, and the stage one is probably closer to a regular performer. I am leaning toward a stage 2, and probably should get it before chinese goods get tariffed. I am also suspecting that the mystery cam that I dont like is substantially limited by the 2v 302 heads. I doubt any work was done on them, and am thinking maybe the bottom end came out of a '60s car with a manual transmission as I had to exchange the 3 bolt balancer for a 4 bolt, and remove a pilot bearing from the back of the crank before bolting in a C4. The engine also had the flex plate from a 6(?) bolted up without any balance weights. So, my theory is that someone got a buddys hot rod motor minus heads, and threw on the 2v heads. The intake was installed with generous amounts of orange gasket silicone that could be seen intruding into the intake ports by looking down the intake.

    All this to say maybe I will swap the heads and leave the cam alone for now. My only penalty for doing it this way will be another set of intake gaskets if I decide it absolutely needs a different cam. Who knows....maybe it will play well with some better heads and bug me less.
     
  15. Hotrock

    Hotrock Rick, an MCCI Member Supporting Member

    Joined:
    Oct 27, 2012
    Messages:
    1,466
    Likes Received:
    713
    Trophy Points:
    313
    Garage:
    1
    Location:
    Munroe Falls, Ohio
    Vehicle:
    1972 Mercury Comet, 1997 Mustang Cobra, 2019 Ford Edge ST
    The gasket silicone intruding into the intake ports is enough to limit performance. I have always been of the mind-set to complete one performance change at a time; otherwise you have no way of determining which change had the greatest impact.
     
    mojo and Krazy Comet like this.

Share This Page