I need new heads for 351W

Rover, I could be wrong but I have the understanding that GT-40 heads are designed for the 302 engine. I also understand the the 351W heads are pretty good in stock form. What is wrong with the heads on your 351? Also, consider that heads with smaller valves will force higher velocity fuel mixture at lower engine speeds resulting in better performance during the low speed operation. Going to larger valves with larger ports may only help in high RPM operation which you may never see anyway. Large valves may reduce low RPM performance. I think you should re-think spending money on heads for a boat engine. Go for high torque at low RPMs and a prop with a big pitch - my 2 cents.

One more article you should read:
http://www.mustangandfords.com/techarticles/5288/index.html scroll down to the subarticles also for some good reads.

JIH is dead on and you can get dissapointed with premium heads depending on what you plan to do with the boat. Big Valves are great above 4500 RPM which is where our boats top out so again, Jim's giving you some good advice. Increased chamber size (will reduce compression) and the larger valves will both hurt low end torque. For semi-displacement hulls IMHO it's all about low end torque. Think water tractor.

A friend of mine bought a used set of GT-40's and was bragging about pulling my boat around the lake. He barely got off plane. Like a couple knuckleheads we thought we checked everything...

We mainly slalom ski and wakeboard and rebuilt a 289 using my old heads with larger valves punched in, but increased the compression and she pulls great. I spent the extra dollars on forged pistons, mild porting, new intake, electronic ignition and carb. I even kept the old solid cam for the reasons Jim stated so I could play with the lash to get the most of the low end torque.

Good Luck!

I think the GT40 heads can be used on the 351W by simply drilling out the bolt holes to accept the larger diameter head bolts used on the 351W vs 302. Remember, I said "think".

I tend to agree with the other statements. Our boats NEED lots of low end torque. The footers may need some high(er) end HP as well.

As I mentioned in other threads I installed a nice set of GT-40P heads on my 289. I lost a little compression and I may have lost some performance but I am happy with the overall performance of the little 289. My reason for installing the heads was purly perverted in that I could not stand the thought of running heads with Ford's stock pressed-in rocker studs. The thought just makes me crazy. The GT-40Ps have threaded rocker studs which is how all studs should be made (IMHO). The pistons are stock original because I did not want to take time playing with clay.

If anyone can recommend pistons that will boost my compression without any risk of hitting a valve I would certainly like to give them a try. I wouldn't mind a little more compression and I am not into head shaving.

Also, I am ready to play with some clay during my next rebuild.

Thanks... Jim

PS: I am now thinking "water tractor". You have to love it.

Thanks GottaSki. How do you zero-deck a block? What is involved?

I beleive what gottaski is refering to is machining down the blocks decks, (surface heads mount to) so that they are flush with the top of the pistion (flat top or dished pistons). This would require no change in parts with the exception of the push rods maybe, depending how much material was removed off of the decks. If you didn't change the length of the push rods then you would be creating more lift on the valves and could posiablely(sp) hit the piston if you did not checked for clearance ahead of time.

Thanks for the great responses....
My heads have many cracks between valves due to over heating.
Everyone has been very helpful here, glad I found it. This is one of a few SN we plan to restore in the near future.
Thanks again
david

Rover
I believe there are a set of DOOE heads on ebay right now and they would be perfect for a 351W most hot roders use these heads over gt-40 if you can get them.

Joe, the pistons are 289 original flat top.

Joe, I'll be waiting to see how you like the GT-40Ps.

Jim,
    I think you should check out the Keith Black KB116 pistons, maybe a little extreme but I am guessing you would end up about 10 to 1 with them and your current setup. Summit has them at about 220 a set. They are hypereutectic cast pistions which are IMHO the best way to go for boat engine. They are lighter and cheaper than forged and more thermally stable so they won't expand as much reducing the chance of scuffing. If you dropped them in your block you would probably gain enough clyinder wall clearence with a little honing to drop them in without any such worries. I found a set of GT40p's at a wrecker down the road for 300, autozone has them rebuilt for 350 a piece, I think I will pick up the ones from the wrecker and find some stainless valves and do a rebuild on them...
Alan,
    I would think that you would see improvements with the GT-40 bolt on.. I see no reason to doubt Vince on it...

Jim,
Sorry for the confusion... I can get used ones from the wrecker for 300 for the pair including valves springs etc, they have 35000 miles on them. If I go that route I would probably put on new springs, stainless valves, light machining, and replace the steel plugs with bronze ones. The ones from autozone are 350 each for completely reconditioned heads with all springs and valves included, they are actually 250 but they have a 100 dollar core charge... if I bought those I would just install them and run them as is... I am leaning towards getting the used ones... stainless valves would set me back about 200 incidentals will probably put the whole thing at 600 dollars installed and done right... not too bad. It would cost 695 a side for the GT40's from skidim and the GT40ps flow a little better and have a smaller and more efficient combustion chamber. Sure the boat already runs perfect, tops out about 46, sounds awesome, and has easily pulled big three slalom skiers up at once but it can always run better right?
-Joe.

Jim, the Keith Black KB116 pistons Joe referenced are the exact ones I've been running for about 5 years now in our 69 blue Mustang 302. They are a domed piston and with the good 60cc D0OE heads which '79 suggested, and which I'm using, they're supposed to yield about a 10.5:1 C.R. according to the Ford Tech Line, with a 302 stroke. Some may feel this to be a bit high, but mine's been bullet proof for some 300 hrs. I'm also using that same cam you mentioned along with the Barr Marine aluminum 3" exhausts, gasket-matched to the ported heads. The holeshot of this boat simple a rush.

These KB116 pistons with the 58cc GT40P heads (I believe Ps are 58 and std GT40s are 60cc, right Joe?) might have you somewhere close to 10.5 with a 289 or 11.0 with a 302 based off the application specs in the PAW parts catalog. It also mentioned that these pistons with the small 54cc 289 factory heads, will need mods done to the piston or head for clearance.

We are putting together a new engine right now with these pistons and World/Roush 180 58cc iron heads which have just been ported, after reading that the factory flow specs were sub-par to the 40s on the intake side, even with bigger 1.94 vs 1.84 valves. I'll let you know how it runs unless it ends up in infinium like so many other of our projects.

As for the GT40 heads on Alan's '81, I believe that to be the best example of where you'll see the largest power gain with the GT40 heads. That vintage 351, if indeed it has the small spark plug (5/8") heads, is basically a 302 head with the smallest valves (1.78" intake) combined with the largest chamber (+/- 69cc). You could pick up in the neighborhood of 2 full points of torque-building compression, whereas you sometimes loose a tad bit as Jim did, as he ended up with a slightly larger chamber than stock. Just make sure it's not too much compression, but Vince I'm sure has seen this combo numerous times.   

Thanks ReidP

Alright so I found a set of gt40p's with a 5 angle valve job, new springs, new stainless valves (slightly larger than stock) basically all ready to go for 500 so off I go (anyone need a set of 1978 302 heads, they have about half a season on them since being rebuilt and I will sell them very very cheap). Anyway now that I am getting in there again, I am starting to think roller rockers, anyone using anything they would recommend and if so what valve covers are you using. I am a little worried that I would drop the money for the rollers and then not be able to find a valve cover that would clear both them and the exhause logs. The cheapie chrome valve covers I have on now specifically state they will not clear rollers. Any suggestions?
-Joe.