GT40P Head Identification

From previous posts the way described to ID these heads was by the 3 line raised casting marks at the front of the heads. Do the heads also have this casting mark (GT40P)to identify them correctly as GT40P's. I have found a set in Australia just trying to confirm they are correct.

lewy2001 wrote: From previous posts the way described to ID these heads was by the 3 line raised casting marks at the front of the heads.

Only thing I can add Mark is the gt40's have 3 raised lines and the P's are supposed to have 4

Lewy, I see 4 bars on top (like Gary mentioned, 4 bars = P heads), and the casting under the valve cover is a good clue as well. Definitely GT40p's.

I think you'll be really happy with a head/cam/intake upgrade. My '90 has all the holeshot and midrange you could ever want in a ski boat. Im sure that package in a 2001 would push it over 50 pretty easily.

Joe, Ive been in a few 2001's that do 45-46 with a stock 240hp engine and an Acme 540. I was able to add 5+ mph to a hull with a lot more drag than most. Add a H/C/I upgrade similar to my '90 and I think its a recipe for a 50mph 2001. Ill keep working on Brad to see if we can modify his stock workhorse '86 in order to prove that theory.

behindpropeller wrote: Mine spins 44k and 44mph... with the bottom waxed it makes it to 45...

44,000 RPM, yikes! You must have a 13"x1" prop!

Seriously, what prop are you running? The 2001's Ive been in consistently spin the 540 to 4600-4700. Its good for a 1-2mph gain over the stock 3-blade.

TRBenj wrote: behindpropeller wrote: Mine spins 44k and 44mph... with the bottom waxed it makes it to 45... 44,000 RPM, yikes! You must have a 13"x1" prop! Seriously, what prop are you running? The 2001's Ive been in consistently spin the 540 to 4600-4700. Its good for a 1-2mph gain over the stock 3-blade.

Tim-

I put a turbine in it....


Spinning a 540. Guess my tach may be off. I should take my GPS out to see what it is doing. All stock 1600 hours.

Tim

I have only tried top speed with only myself in the boat,and even after the head change my speed is the same 45. Hole shot and mid range seem better. I need to get a couple of passengers and possibly a new prop and give that a try.

my new gt40p heads have the 4 bars.. they have a casting number that starts with 9...
hope i can get to 47-49 with all my upgrades!!!
Joe quite a nice engine for a backup one!!

Not that I´m a speed addict but 46-48 sounds good to me...could no tell about were the spray breaks on mine but y guess its a little forward of the skeggs..but as I drive the boat, I´m not sure..
When boat ready for top speed test drive I will have another boat to take some pictures, good ones as I don´t have pics of it while cruising!!!.

Seb, each hull pops out of the mold a bit differently. There were probably multiple molds as well- so while we do have the same hull, no 2 are exactly the same.

If it came out of the mold with less hook, it will run a little more bow high, which means there is less wetted surface (drag) and the boat will run faster. You will notice that the spray breaks further back towards the pylon or motorbox on a bow-high hull.

If it came out of the mold with less hook, it will run nose low. This means more wetted surface (and more drag) and the boat runs slower. My '90 is the worst Ive seen in this regard, and the spray breaks at the forward part of the windshield- I can see it when I drive. Keith's '94 and my uncle's '90 run noticeably more bow high. My '90 was a real underperformer when I bought it- it turned a cool 41mph @ 4200 RPM's until I threw some power at it. Now I get a consistent 46, and will hit close to 48 with ideal conditions, a full tank of gas, and 4 bodies in the back seat. Its a little pathetic! Holeshot is pretty respectable though.

Unless youve got some weight in the boat (in the rear) then it looks like it rides fairly bow-high to me. Mine runs pretty flat at all speeds.

as for the cast on the heads, mine do have the gt40p cast on them...and the 4 bars also

Sebastian,how did you get the brass freeze plugs? When I ordered mine they said I could not get them. When the warrenty goes off I'll just replace them.

I posted somewhere else that a big ford guy told me that the older Aussie ford built heads were better than the US built heads...why, I dont know, emissions? has anyone else heard this?

I picked up those GT40p heads a couple of weeks back. Have been looking for a inlet manifold before I do the head swap. This manifold turned up on Ebay.

Intake Edelbrook

It looks to be a single plane highrise. Not a air gap more like a Victor Jnr. Not sure if it will be any good for a ski boat. I know Joe put a single plane on his stroker but it had bags of torque anyway.
What do you think it only has 40mins to go so I need to act fast. We just dont see many 351W manifolds in Aus plenty of 302W.

Also would it clear the engine cover ??