94 Ski 351 head upgrade?

[mgswed]

Okay, so i am toying with the idea of upgrading to the GT-40 heads and i am trying to collect some information. How hard of a process is this? I have been reading and there are several types of GT-40 (x,p,regular,etc). Which is recomended? Where can I get a good price on a set of these (ones that are recommended)? Is there a set process taken to do this? If anyone can shed some light on this it would be greatly appreciated. P.S. I dont have much experience with engines, but am willing to try this depending on opinions recieved. Thanks -MG

[darrel409]

RE: 94 Ski 351 head upgrade?

Check on Correctcraftfan.com They have had many discussions regarding head upgrades. There was a new thread yesterday by "gottaski" in the EngineRepair index.

[siuski]

RE: 94 Ski 351 head upgrade?

Have you found heads for the 351 yet? Last year I was forced to replace my stock (non-gt 40) heads and couldn't find a set to save my life; rebuilt, new, or otherwise. When I went to upgrade, skidim was the only place I could find them. There may not be a choice of the differnt types. Good luck.

[HankCobb]

GT-40 P Head Upgrade - no prob

Howdy,

I did a GT-40 P head upgrade about 3 years ago on my '91 Excel. As well as edelbrock intake, phenolic plastic spacer, & Edel Marine Carb. I run it up to 8,000 feet altitude in Utah, nice addition for hp upgrade. Good winter project.

- you need to use the "P" Heads because the spark plugs need to be at an angle for header clearance

-you will need to make a custom teflon/stainless braided fuel line from the fuel pump to your carb, a good hose shop should be able to do it for about $100-150

Ford Racing Part# M-6049-P303 $240 each (Ford Dealer)
Edelbrock #2181 Dual Plane Intake Manifold $155.64
Edelbrock #1409 Square Flange Marine 600 CFM Carb $299
-can still use holley carb, may need the standard flange adapter plate?
-Edelbrock #2732 approx $20
Vince at Discount Inboard Marine www.skidim.com
stocks the "P" heads as well.

PS: I sold my heads & holley carb on ebay to get some cash back out of the deal, trashed the heavy old intake manifold

[83sn2001]

RE: GT-40 P Head Upgrade - no prob

Hankcobb, What was $240 bucks each from ford?

[DavidF]

RE: GT-40 P Head Upgrade - no prob

the cylinder heads.

[M3Fan]

Re: RE: GT-40 P Head Upgrade - no prob

the cylinder heads.

That seems much cheaper than the 600+ at SkiDim

[mgswed]

GT-40 P Head Upgrade

Thanks for all the info. How much HP and MPH will it add? -MG

[TRBenj]

Re: GT-40 P Head Upgrade

Thanks for all the info. How much HP and MPH will it add? -MG

100 HP and 15 MPH.























j/k :razz:

Actually, the regular GT40 heads should add ~2 mph top end. My experience is with the 1.23:1 tranny, but your results with the 1:1 should be similar. 30HP is probably about what you would get- that was about the difference between PCM's motors (standard 255HP and 285HP ProBoss) in the early 90's.

However, I would research more on head upgrades for the 351. As I understand it, it is generally not recommended to put a 302 head (like the GT40P) on a 351 as it would choke the motor relative to others designed for more cubes. The more cubes, the more the motor needs to breath. Automotive heads swap right onto these motors, reverse rotation or not (which yours is). Therefore, I suggest you read more about 351W upgrades on automotive forums such as corral.net (mustang forum) and fordtrucks.com. Applications on trucks may provide more useful information to us boating folks since lower-redlining torque-rich motors are a goal we share with them.

Automotive heads can also be found cheaper than DIM sells for, and there are no differences. As far as cast iron vs. aluminum there are currently arguments on the "other" CC forum discussing pros and cons to the aluminum. Lots of info out there...

Happy reading Gates

[M3Fan]

RE: Re: GT-40 P Head Upgrade

If you read Skidim's site, they mention that they are NOT the P heads. what the heck is the difference?

[TRBenj]

GT-40 P Head Upgrade

GT40P's were the heads put into the 97+ Ford Explorer/Mercury Mountaineer with the 5.0L (302). They flow better than the regular GT40 heads (originally available on the SVT Mustang Cobra from the early 90's I believe), especially on the intake side- though the exhaust valves flow slightly better as well. The P's have a slightly smaller combustion chamber, thus raising the compression ratio. This has the effect of improving performance and requiring a higher octane gas.

The angle of the spark plugs are different than "normal" Windsor heads, causing exhaust header conflicts on the Mustangs. They dont interefere with the exhaust manifolds on our boats though, at least no one has any problems running them on their vintage Correct Crafts.

Again, those who are running them on boats have 289's or 302's. The head bolt holes would need to be bored out to fit on a 351 I believe. While they may be an upgrade over the stock heads on a 351, they would ultimately be a weak point on a motor with many upgrades due to the extra cubic inches.

My .02