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87MCProstar
03-08-2010, 02:33 PM
Hey guys just curious if anyone know the largest specs we can get in a Ford 351, with the gt40p heads?

Kyle
03-08-2010, 07:49 PM
Hey guys just curious if anyone know the largest specs we can get in a Ford 351, with the gt40p heads?

I have the factory cam specs for you. I need to get it on here some how. I will scan it. Indmar and PCM will charge you 699.00 for a new cam.

I just had the factory spec cam grinded and it was 180 from Comp cams. I am running gt40p heads as well.

Kyle
03-08-2010, 07:53 PM
If you go too big the engine could suck water back through the exhaust valves. Texas Mastercraft told me do NOT change the cam. Just get the specs and have one made is what they told me.

I have heard that .500 lift and .475 were the max you could go. I think that the specs are a .456 and .457 Its pretty close so I used a factory cam in my new rebuild. I will post the specs on here later. Need to go to boat storage to get the sheet. Will be up there tonight.

Kyle
03-09-2010, 12:50 AM
Ok I am not so up to speed on how to edit and make the scan fit so forgive me.

I know 100% that this is the spec sheet for a 351 HO motor from the factory. I sent a cam 2 years ago to COMP CAMS and they researched the serial number and the grind number with Ford. They also measured the cam for extra security that the info Ford gave them was correct.

I just installed this cam in my boat and like it. Origionally I had to replace a cam in my friends 205 with 351 HO because it had a bad lobe. The engine had never been taken apart and intake had never been removed. This is how I know for sure that these specs came out of a factory 351w HO motor with gt40 heads. The only difference between the gt40 and the gt40p heads are that the gt40p heads have different spark plug angle. It is more center giving better combustion. The other difference is that you will need to drill out all of the head bolt holes as the gt40p heads are not big enough for a 351 bolt to go through them. I took a 1/2 bit and slick 50 spraying bit and drilled every hole making them bigger. You can also take it to a machine shop and they can use a drill press. I trusted my hand and a drill with a friend spraying lube on the bit. Mine works great.

Hope this helps

CantRepeat
03-09-2010, 07:12 AM
Sounds strange that you would have to drill out the bolt holes. I thought the valve sizes were different in the Ps as well.

Kyle
03-09-2010, 08:28 AM
The P heads are a 302 head. The gt40 non p head is a 351 head. It was not hard at all and took about 15 min. Then took a pressure washer to them and followed up with compressed air. They were good to go and installed nicely.

Kyle
03-09-2010, 08:30 AM
I have heard that the P's flow better than the gt40 non p

87MCProstar
03-09-2010, 08:32 AM
Kyle, thanks for the info. I'm going to store this aside. I've had my motor rebuilt two summers ago, a little beefier than stock. But since I'm a speed junky and I barefoot I need to go a little faster. The boat is toping out at 45 without me on the rope and drops to about 42.5, I'd like to hit upper 40s. Looking for ly6 numbers out of the small block. I'm getting married this summer so this project is on hold until next winter, but new heads and cam are the way I want to go.

Kyle
03-09-2010, 08:35 AM
You should like the heads. I am running 44 gps stargazer and have not proped the boat yet. I am about to work with oj on getting this right.

87MCProstar
03-09-2010, 10:34 AM
Wow, thats pretty impressive you're running 44 with all the weight (radio/amps/batteries) in your boat.

TRBenj
03-09-2010, 01:07 PM
Tim, feel free to drop me a line if you need info on my GT40p set up. In my experience, Comp's grinds leave power on the table, at least the ones Ive seen for small block Fords. I went with a company that only does Fords (Cam Research) and couldnt be happier. No need to go overly aggressive- Im in the .490/.490 range, and see peak power ~5000 or so according to my desktop dyno. My boat only pulls 47-48mph, but can hold 45 or so with 2 big footers behind it.

The info above on the p heads is correct- theyre 302 heads (7/16" bolt holes) so they need to be drilled out to 1/2" for a 351w. I sure as heck wouldnt be doing that by hand, though- that should be done with a drill press.

The info you heard about big cams isnt entirely wrong- but nothing anyone here is considering is anywhere near that threshold. It takes quite a bit of duration and a fairly narrow lobe separation angle to have reversion issues. Small block engines run pretty small cams- so dont sweat an upgrade. For example, my buddy is running a pretty aggressive roller cam in his 408w (stroked 351w)- something approaching .550/.550. No issues. Ill be running something even bigger in my big block Chevy this summer, and in the grand scheme of things, its still considered a relatively tame cam.

87MCProstar
03-09-2010, 01:13 PM
Tim,
Performing a new project? New boat or just new motor?? I was wondering what that companies name was. I'm gonna definately get ahold of you after this season is over.

CantRepeat
03-09-2010, 03:15 PM
I guess I was unaware about the bolt sizes. I've never had my heads off and it came factory with the 285hp and P heads.

TRBenj
03-10-2010, 10:23 AM
I guess I was unaware about the bolt sizes. I've never had my heads off and it came factory with the 285hp and P heads.
Uhh, no it didnt. The P heads never came from the factory on any 351w, marine or otherwise. They only came installed on 1997-2001 Ford Explorers and Mercury Mountaineers (5.0/302). The marine HO 351w's came with regular GT40's... slightly different animal.

Tim, whole different boat. Dad and I are restoring a '79 Barefoot Nautique. It ran 56 or so last summer- should be good for 60 come springtime.

rd1900
03-10-2010, 11:43 AM
When you are making your head/cam changes are you doing anything with the intake manifold? What about air flow and fuel flow?
Granted, the GT40P head flow better than stock, and an bigger cam increases flow more, but is the intake a restriction? Is the air flow into the motor box a restriction?
At least on my '89 PS, all the engine air comes through two long, rather small, hose with some pretty messing routing. At 351 cubic inches, and 4000 rpm, you need to pump something like 325 cubic feet of air per minute through the engine (at 85% volumetric efficiency). I have a hard time believing those two little hoses on my boat can support this. Maybe I'll test performance with the engine cover on and off and see if there is a difference.
And what about fuel flow? Can your carb of TBI keep up with the increased air flow thought the upgraded heads and cam?

TRBenj
03-10-2010, 11:56 AM
Yes, an intake upgrade is usually recommended. Run the tallest dual plane you can fit under your motorbox. The Edelbrock Performer RPM and Weiand Stealth are both good choices. The regular Performer is an inch shorter and is a good choice is clearance is tight.

Ive run enough with an open motorbox to know that the engines in my boats arent starving for air... but I own CC's that have 3-4 3" vent tubes running into the engine bay. MC's may be be borderline sufficient- do some testing on your own. I know my buddy's '95 PS190 will run 1-2mph faster with the motorbox open.

As far as fuel goes, these mods usually wont require jetting changes- but a plug chop will tell you for sure if youre running lean. I converted my 4160 to a rear metering block with replaceable jets so I could dial in the air/fuel mixture... but Im not fattened up much over stock on my 351w (which also has an exhaust upgrade).

Kyle
03-11-2010, 05:39 PM
I guess there is always someone who will shut down someone elses knowledge.

#1 Why would comp cams grind a cam incorrectly if they have the exact specs from Ford.

#2 If power was left on the table why in the last 2 351w engines that I have assembled did the boats run the same or faster than factory. GPS PROVEN

#3 Some people dont want a lope to their motor so factory may be the best opion. If running to much lift, duration, or overlap you CAN suck water in from the wrong way.

#4 Why on earth would INDMAR put a low performance cam in the boats from the factory. A cam is like $200 so putting in a cam that would not perform well would be out of the picture. There is a reason why they put that specific cam in.

#5 Running 50 mph is probably out for any prostar. There is only 1 TT member who can run that fast. 03 35th He has a SUPER CHARGER on it. I am also friends with the tech at TXMC who installed the SUPER CHARGER. After tons of tuning and prop work they finally got the boat tuned properly.

#6 The LQ9 that was in the ps197 does not run 50mph from the factory and it is 385 hp.
I would think if you did a complete rebuild adding good internals you could push 400hp. You still are not going to go over 50 mph.

#7 Any prostar is a very wet hull. You will need more than 400 hp.

#8 The Barefoot Nautique I do believe comes with a 454 in it. At least one of my friends nautique has one in it.

I would consider the boat that you have and go test drive a brand new 197 or 190 with the biggest engine that your dealer has and then make your decision. Its going to take a lot of hp to get you to 50.

TRBenj
03-12-2010, 04:43 PM
I guess there is always someone who will shut down someone elses knowledge.

#1 Why would comp cams grind a cam incorrectly if they have the exact specs from Ford.

#2 If power was left on the table why in the last 2 351w engines that I have assembled did the boats run the same or faster than factory. GPS PROVEN

#3 Some people dont want a lope to their motor so factory may be the best opion. If running to much lift, duration, or overlap you CAN suck water in from the wrong way.

#4 Why on earth would INDMAR put a low performance cam in the boats from the factory. A cam is like $200 so putting in a cam that would not perform well would be out of the picture. There is a reason why they put that specific cam in.

#5 Running 50 mph is probably out for any prostar. There is only 1 TT member who can run that fast. 03 35th He has a SUPER CHARGER on it. I am also friends with the tech at TXMC who installed the SUPER CHARGER. After tons of tuning and prop work they finally got the boat tuned properly.

#6 The LQ9 that was in the ps197 does not run 50mph from the factory and it is 385 hp.
I would think if you did a complete rebuild adding good internals you could push 400hp. You still are not going to go over 50 mph.

#7 Any prostar is a very wet hull. You will need more than 400 hp.

#8 The Barefoot Nautique I do believe comes with a 454 in it. At least one of my friends nautique has one in it.

I would consider the boat that you have and go test drive a brand new 197 or 190 with the biggest engine that your dealer has and then make your decision. Its going to take a lot of hp to get you to 50.
Oh goodness. A few comments:

#1: Its not ground incorrectly, its just not optimized. Ive seen Comp SBF grinds with similar lift and duration numbers to the Cam Research cam that Im running, but when plugged into the dyno, were 30hp lower. There's more to it than pure lift- timing events are VERY important. The Desktop Dyno software also outputs a # of "free hp" that you are capable of capitalizing on based on your inputs... my Cam Research stick only left 3hp on the table. Shows that Cam Research knows their Fords! Not knocking Comp- Im buying my BBC cam from them.

#2: Like I said, I didnt say a Comp wouldnt be better than stock... but there are better cams out there. Cam Research knows Fords, and they know ski boats. Call them up and talk to a tech (Scott will probably answer the phone). See if they inspire more confidence than a Comp tech. I bet they will!

#3: It has nothing to do with lope. My grind is not that aggressive- Im still under .500 of lift. No reversion problems here. I picked up a ton of holeshot and midrange- isnt that what its all about? Optimizing the performance of our ski boats? The top end gains were a bonus.

#4: Indmar didnt put any cam in the engine. They bought a longblock from Ford. Ford put in a very tame, low performance cam. Prove to me that its not the same cam they put in one of their low end truck motors. I bet you cant! Ive yet to see any documented proof that the HO 351w (285hp) had a different cam than the lower end 351w (240hp). Its all in the heads.

#5: Not true. The 197 slow is slower than death, sure. My buddy has a '95 PS190 with an LT1/1:1 and it will run 51 on the GPS... 53 with the motorbox open! I believe he's ported the exhaust manifolds a little- but the boat has always been fast. Its all in the hull though, youre correct. My other friend's '94 PS190 with the same powertrain isnt nearly as fast.

#6: Agreed. The 197 hull is sloooooow. My group of friends likes to barefoot... probably why there arent any new MC's in the loop.

#7: Not true (see above). The 95-97 hull is pretty fast, in my experience.

#8: True, our BFN has a big block. BFN's only run 48 or so from the factory though... so to make one run 60 isnt easy either. My other CC's suffer from slow hull syndrome, just like many MC's do, and I dont have the big block advantage. I can still build a small block that will surprise you. Ask 87MCProstar... he's ridden in my slow boat.

rd1900
03-12-2010, 04:49 PM
TRBenj - If I wanted to buy the same cam you have from Cam Research, is there is part number or something I could reference with them?

TRBenj
03-12-2010, 04:58 PM
To my knowledge, my cam was a custom grind. Tell them what youve got for heads, intake, compression ratio and ignition, and tell them what your goals are. They'll make a good recommendation.

CantRepeat
03-12-2010, 05:29 PM
Uhh, no it didnt. The P heads never came from the factory on any 351w, marine or otherwise. They only came installed on 1997-2001 Ford Explorers and Mercury Mountaineers (5.0/302). The marine HO 351w's came with regular GT40's... slightly different animal.

Tim, whole different boat. Dad and I are restoring a '79 Barefoot Nautique. It ran 56 or so last summer- should be good for 60 come springtime.

You are correct, I was totally thinking of the GT40 heads, which also led to the didn't know you had to drill the head bolt holes out. Sorry.