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GT40 heads at SkiDim

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tommer12 View Drop Down
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    Posted: May-26-2004 at 7:32pm
Anyone see this? So the GT40 heads are floating back around.... I have the 92' PCM ford 351.... is it worth the upgrade for the heads to purchase them at $695 each....

if I do purchase them... how hard is it to bolt new heads on?
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64 Skier View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 64 Skier Quote  Post ReplyReply Direct Link To This Post Posted: May-27-2004 at 12:16am
In some applications, the GT-40's won't bolt up to your exhaust. Call and make sure.

Ford Racing has several versions of the GT-40. May want to give them a call to ask their opinion versus what your looking to gain.

64 Skier
66" HO VTX and 67" HO Triumph
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882001 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 882001 Quote  Post ReplyReply Direct Link To This Post Posted: May-27-2004 at 1:32am
or call and ask vince
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AWhite70 Quote  Post ReplyReply Direct Link To This Post Posted: May-27-2004 at 11:51am
You can generally find used GT40's on ebay for much less than $1400 a pair (usually $400-$500). You'd have to have the head bolt holes drilled out to the 351 size but that wouldn't cost much.

Ford Racing doesn't sell (or produce) the iron GT40 heads anymore, the only versions still available are aluminum. New GT40P iron heads are readily available, fairly inexpensive and perform better than GT40's, but they have a smaller combustion chamber and could push your compression ratio higher than you'd like.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 64 Skier Quote  Post ReplyReply Direct Link To This Post Posted: May-28-2004 at 11:17pm
Ford Racing Mag 2004

GT-40 "Turbo-Swirl" Aluminum heads @ $525/per complete w/ 1.94-1.54

GT-40X $625/per with an option of 58cc or 64cc with the same valves as above.

Skidim is a great place, and I love Summit Racing also, but sometime Ford Racing is hard to beat and they do have a good technical staff.
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workky View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote workky Quote  Post ReplyReply Direct Link To This Post Posted: June-26-2004 at 7:09pm
i picked up a set of the gt-40p heads from my local motorsports dealer for 242.00 a piece complete
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 64 Skier Quote  Post ReplyReply Direct Link To This Post Posted: July-14-2004 at 2:19am
workky,

How did the new heads turn out. What exhaust were you using and did you feel any gain?

I'm running Barr marine and am worried they'll hide any positive affects a quality head may have???
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 77stang Quote  Post ReplyReply Direct Link To This Post Posted: July-14-2004 at 7:31pm
Ford claims the GT-40 "Turbo-Swirl" Aluminum heads @ $525 bolt on 40hp and that the GT-40X @ $625 will bolt on 65hp. These are BIG numbers. Not to mention the weight reduction.

In other words, for $1400 I can up my 220hp 302 to about 280 hp. Based on this mans math that’s a 27% increase. Now since I cant run a bigger diameter prop I guess I would have to make it up in pitch. (i’m already running 12x14 cupped with a top end very close to, if not, 50mph)

Why do I get the feeling that at 280hp I'm going to be running out of a suitable platform to keep a plane? Additionally, what am I to do with my plans for a performer manifold? Heck, lets do it all - kind of sounds like fun.


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64 Skier View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 64 Skier Quote  Post ReplyReply Direct Link To This Post Posted: July-14-2004 at 10:01pm
77stang,

I've got the old heads/valves on mine and am sure one day the unleaded will ruin my performance so a "head" upgrade is in the near future. Hollman and Moody installed a lot of 351 heads that have larger valves than a 289 head. The original 289 heads can have larger valves put in for about$300 total and this could be a better "flow match" for your exhaust. I've got BARR Marine and am not sure how they work (or restrict) the performance of a high dollar head like GT40's or Edelbrock.

I love my old boat, but quite frankly for a 16' Tow boat that does strange things at 40-50 MPH I don't really need more HP. A reduction in prop pitch is all my "water tractor" needs. With the 12RH14 Prop it still pulls a 250Lb Slalom skier on a very small ski.

Heads alone are a good upgrade as long as your exhaust header is not the choke point...that's what I'd like workky to tell us.

It is very cool though to be able to "snatch" the 250 LB slalom out of the water after your friends big Sea Ray drags him for 20 yards....but the Sea Ray was full of beer and thongs.......

64 Skier
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 66polyhead Quote  Post ReplyReply Direct Link To This Post Posted: July-14-2004 at 10:13pm
Most people get horsepower crazy, always keep in mind: Horsepower is a by-product of torque. a boat doesn't need a lot of horsepower to be quick, or fast. Torque is what gets the boat mooving. If you want easy bolt on horsepower + killer torque, why dont you bolt on a supercharger? That will solve a lot of problems.
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Dallas View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dallas Quote  Post ReplyReply Direct Link To This Post Posted: February-10-2005 at 4:21am
So is anyone using a set of heads other than what was stock on there 351 engine? Any issues with useing Aluminum vs cast iron?
Thanks
Dallas
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64 Skier View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 64 Skier Quote  Post ReplyReply Direct Link To This Post Posted: February-10-2005 at 6:44am
Take a look at this Web Site. Takes some out the myth out of buying a set of heads

http://www.allfordmustangs.com/Detailed/630.shtml

aluminum works well.
64 Skier
66" HO VTX and 67" HO Triumph
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dallas Quote  Post ReplyReply Direct Link To This Post Posted: February-11-2005 at 3:11am
Thats a great site. If you read many of the posts on those sites, They seem to swap heads all the time, with little concern for the change in combustion chamber volume, but more concern for the flow.

Dallas
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64 Skier View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 64 Skier Quote  Post ReplyReply Direct Link To This Post Posted: February-15-2005 at 5:57am
Yes they do change heads a lot. You can put on different heads and ruin performance if your not carefull about the compression.

I'm considering doing the same....but I'm going to measure the port size on my exhaust manifolds and make sure they don;t restrict the new heads.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote captan1 Quote  Post ReplyReply Direct Link To This Post Posted: February-16-2005 at 9:58pm
I'm doing the gt40P Explorer head swap now. The head exhaust port is a good match for the SkiDim sold exhaust gasket and a better fit to the manifold, in other words the exhaust manifold is a little bit bigger than the gt40p head port. I've got to tell you these stock ford gt40p heads look much better than the 351 heads that came on the motor, speaking of the smooth and larger ports and they have a raised valve cover gasket seat for better sealing if anybody's had that problem. The last thing I had to tweak was a 64 El Camino but sold it, that was the first motor I put after market heads on, it made a big difference from stock. You can cam it, replace the intake but if you leave the stock small heads on you still have a bottle neck path.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote reidp Quote  Post ReplyReply Direct Link To This Post Posted: February-23-2005 at 3:26pm
Steve,
Regarding the head swap, I'm really interested in how it comes out performance-wise. Noting the larger manifold port to smaller head port match-up, do you plan to gasket-match the exh port, which would add even a few more horses, as even those P-heads still have relatively small ports. Opening them up is not a large deal at all as you're probably aware. And your gain in compression I think will be a very beneficial but not too extreme gain, which will probably necessitate premium fuel, but many of us use that anyway. If your current heads were small plug heads, your gain should be significant with your valve sizes increasing and your chamber c.c. decreasing quite a bit. The compression ratio may be as high as 10:1, which from my experience is still not too high with a constant flow of good cool water.
ReidP
1973 Mustang

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Post Options Post Options   Thanks (0) Thanks(0)   Quote captan1 Quote  Post ReplyReply Direct Link To This Post Posted: February-24-2005 at 2:44am
OK here goes, I had a chance to take out the boat today but only for about a ½ hour, I hooked up the o’l toilet plunger fake a lake in the driveway and got it tuned first. I put on gt40p heads, Weiand stealth dual plane intake, carb and a Mallory Unilite, all at once. , I know I know, don’t swap more than one thing at a time, ,but at the time how could I wait.
I’m pleased with the performance, seems to spin more freely, I know it breathes better, remember it’s an air pump but it’s hard to tell, it’s not rubber on the road, it’s a prop spinning and slipping in the water. I know it sounds like you’re going to town with the engine cover off on the lake.
It had a slight stutter gunning it after idling for a while but no oil leaks or water. Just knowing what I have under the hood is half the fun.

The old heads where D8OE 69cc chambers I think. Might try the original Holley too.
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