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riggsy3
10-03-2011, 10:04 PM
Hi, new to this forum. Question: will gt40 or (p) heads fit on my 1987 indmar 351W (5.8) and accomodate my stock E6TE intake manifold + indmar exhaust manifolds and have valve clearance. I know the head bolts are different (1/2 inch for 351). Don't want to invest $ in gt40 (p) heads and find out they won't work. Your input is appreciated

CantRepeat
10-03-2011, 10:06 PM
There are few threads running in the engine section of this forum right now about gt, gt40 and gt40p heads that answer all of your questions.

http://www.mastercraft.com/teamtalk/showthread.php?t=44156

It's now just 2 threads below yours.

thatsmrmastercraft
10-03-2011, 10:06 PM
Hi, new to this forum. Question: will gt40 or (p) heads fit on my 1987 indmar 351W (5.8) and accomodate my stock E6TE intake manifold + indmar exhaust manifolds and have valve clearance. I know the head bolts are different (1/2 inch for 351). Don't want to invest $ in gt40 (p) heads and find out they won't work. Your imput is appreciated

In a word..................yup.

riggsy3
10-03-2011, 10:17 PM
yes, thanks, I saw thread regarding similar circumstance but read nothing about stock intake match-up. trying to cover all bases before making a purchase. Again, thank you.

thatsmrmastercraft
10-03-2011, 10:21 PM
yes, thanks, I saw thread regarding similar circumstance but read nothing about stock intake match-up. trying to cover all bases before making a purchase. Again, thank you.

Would be a fine time to upgrade the intake too, but the stock intake will work just fine. HP = $$$.

riggsy3
10-03-2011, 10:25 PM
Not opposed to upgrading intake manifold. Would you happen to know what kind of intake manifold would work or perhaps a website that has the info. Thanks

j.mccreight@hotmail.com
10-03-2011, 10:40 PM
Not opposed to upgrading intake manifold. Would you happen to know what kind of intake manifold would work or perhaps a website that has the info. Thanks

Edelbrock performer or edelbrock performer rpm or weiand stealth. Just depends how much hp your going for and if any other components are replaced with performance parts.

thatsmrmastercraft
10-03-2011, 10:47 PM
An Edelbrock Performer would be a fine choice. http://www.edelbrock.com/automotive_new/mc/manifolds/ford/ford.shtml

These can be found at Summit Racing http://www.summitracing.com/parts/EDL-2181/ or Jeggs Performance http://www.jegs.com/i/Edelbrock/350/2181/10002/-1

tommcat
10-03-2011, 10:51 PM
An Edelbrock Performer would be a fine choice.
that would be my choice as well

riggsy3
10-03-2011, 10:58 PM
Thanks for your info. Will look into the intakes you suggested. I do understand the hp chain of events to an extent. I'm not necessarily looking for lots of ponies, but if it happens as a result of better performing heads and intake without having to change the cam or crank or other major components then thats great. As I see it, my choices at this point are gt40(p),E7TE (or similar)or try and find the original E8JL heads. Regards

j.mccreight@hotmail.com
10-04-2011, 10:21 AM
Thanks for your info. Will look into the intakes you suggested. I do understand the hp chain of events to an extent. I'm not necessarily looking for lots of ponies, but if it happens as a result of better performing heads and intake without having to change the cam or crank or other major components then thats great. As I see it, my choices at this point are gt40(p),E7TE (or similar)or try and find the original E8JL heads. Regards

I highly doubt your going to be able to find the E8JL heads.

thatsmrmastercraft
10-04-2011, 10:41 AM
Changing heads and intake, as long as there isn't a huge compression increase (which there isn't in this case, is relatively safe HP. Once you get to the level of changing the cam, now you really need to look at the condition of the rest of the engine so you don't overbuild the top compared to the bottom and build a grenade.

How many hours on your engine?

Kevin 89MC
10-04-2011, 04:06 PM
FWIW, I just changed stock heads to GT40 (non-P) heads, stayed with the original intake. I posted about it a few months ago, with pics. I noticed a definite power gain with just the heads. I've heard conflicting answers on how much more power I now have, but it is definitely noticeable. Top speed went from about 41-42 to about 46, which indicates significant HP gain. We are not able to slow it down as much when slalom skiing, haven't had the chance to foot behind it yet. Doing the heads was a fair amount of work, but swapping out just the intake later should be pretty easy, one reason I did not do it at this time (that, and lack of money). Good luck,
Kevin

joniron1
10-04-2011, 06:02 PM
You will not regret getting gt40p heads . I did mine this spring and the increase in pulling power is awesome . No problems just a bolt on upgrade ,except for the bigger head bolts (mine came with the holes bored out and brass freeze plugs installed) .

riggsy3
10-06-2011, 09:01 AM
Hey thanks, found gt40p heads but haven't gone to get them yet so I haven't see them, hours on engine unknown since hour meter not working (my guess is just under 1000). Engine "looks" pretty tight, no sludge etc., marine mechanic also said engine looked good, we'll see. My question is about the rockers. I would like to upgrade to roller-tip rockers but dont know if the gt heads are pedestal and if so what stud height/diameter, do I need a conversion kit or will my old stock rockers work. BTW, if anyone has a trashed E8JL head and would like my old one (its in pretty good shape) let me know. Thanks for your help

TRBenj
10-06-2011, 10:53 AM
P heads still use pedestal mount rockers. You can reuse the ones from your old heads. You can also upgrade to roller rockers if you want, but the hp/$ ratio gained with them is very, very low. Crane and Scorpion are the 2 brands I would trust.

Regardless of which heads you use, be sure to check your lifter preload when you reinstall your valvetrain. I would check every single lifter- Ive seen them vary by as much as .060 on the same head due to variances in the cam, lifter, pushrod, valveseat, pedestal base, etc. This is especially important on a set of head that have been remanufactured, as you will likely be shimming every single rocker. Comp has a good procedure detailed online- use a google search. Follow the section that details setting lifter preload on a "nonadjustable valvetrain".

riggsy3
10-06-2011, 12:52 PM
Thanks for the help on setting lash & preload, read crane cam procedure, looks fairly easy to adjust. I'm getting conflicting stories on performance or wear differences with roller vs. non on rockers, will have to weigh the pros and cons. Cant wait to get back on the water but dont want to make a costly mistake being in a hurry due to aqua-anxiety! PEACE

Phntmski
10-06-2011, 01:43 PM
I have a '91 PS 190 with the small 351W and power slot. Engine runs like a dream but have been jonesing for more power. It's an agonizing decision for me to tear into a perfectly fine running engine for the more power that's available vs "if it ain't broke, don't fix it". Next question is how much to do. If I change the heads/intake but don't match the cam and check the crank how much HP am I leaving on the table?

thatsmrmastercraft
10-06-2011, 01:59 PM
30 hp is the claim for the heads and another 10 - 15 for an intake. Once you start thinking of the camshaft + route, it's really time to freshen up the whole engine.......especially on a 20 year old engine. If it were 3-5 years old you could get away with more.

Ryan
10-06-2011, 02:43 PM
Worked very well for me with stock intake. I had a machine shop increas the bolt hole diameter and popped them right on.

thatsmrmastercraft
10-06-2011, 02:53 PM
Certainly no need to replace the intake. But, as long as it's off, and it's in the budget.....

gr82bgreen
10-06-2011, 02:57 PM
P heads still use pedestal mount rockers. You can reuse the ones from your old heads. You can also upgrade to roller rockers if you want, but the hp/$ ratio gained with them is very, very low. Crane and Scorpion are the 2 brands I would trust.

Regardless of which heads you use, be sure to check your lifter preload when you reinstall your valvetrain. I would check every single lifter- Ive seen them vary by as much as .060 on the same head due to variances in the cam, lifter, pushrod, valveseat, pedestal base, etc. This is especially important on a set of head that have been remanufactured, as you will likely be shimming every single rocker. Comp has a good procedure detailed online- use a google search. Follow the section that details setting lifter preload on a "nonadjustable valvetrain".

I wonder how many guys check rocker arm preload. I bet not many. Most will get lucky and run ok, but may be running with very minimal preload or possibly too much preload if the heads have been planed. Always a good idea to check

TRBenj
10-06-2011, 05:21 PM
30 hp is the claim for the heads and another 10 - 15 for an intake. Once you start thinking of the camshaft + route, it's really time to freshen up the whole engine.......especially on a 20 year old engine. If it were 3-5 years old you could get away with more.
Hogwash. Id be interested in hearing your rationale for how a set of heads and intake dont stress an engine, but a cam will. All 3 parts do the same darn thing- improve the engine's breathing. If the engine is in good shape, then upgrading the top end is just fine. No need to "freshen up" an engine that doesnt need it.

Assuming you'd be forgoing a good cam, you might be leaving as much as 30hp on the table. I would venture a guess that the P heads and intake will put a 351w in the 280-300hp range, and the cam will get you closer to 320hp. That cam will make the most of your other components. Of course, you add the cam by itself and it wont do much of anything (good, anyways).

I'm getting conflicting stories on performance or wear differences with roller vs. non on rockers, will have to weigh the pros and cons.
Roller rockers are nice and will be slightly more accurate (assuming youre buying a quality brand) than the stamped steel non-rollers. They'll be a little lighter (aluminum vs. steel) and will offer less friction, but youre not talking serious hp. You may make the engine a little more responsive, but I doubt youre adding more than 5-10hp. This is coming from a guy who has installed multiple sets on his boats.

If you have the money to buy them and its burning a hole in your pocket, Id be more inclined to recommend a roller cam conversion. That will offer even more of a friction decrease. The big seller is the power improvement- you can run steeper ramp rates with a roller cam than a flat tappet. It is also a reliability improvement... flat tappet cam failures are not uncommon, especially with today's oils. Of course, the investment is an even bigger one, as you'll need new tiebar lifters, new pushrods, the cam itself will be a bit more expensive, and you'll also need a new distributor gear... so long story short, you may be best off putting that money towards gas- especially if youre itching to get back on the water!

TRBenj
10-06-2011, 05:26 PM
I wonder how many guys check rocker arm preload. I bet not many. Most will get lucky and run ok, but may be running with very minimal preload or possibly too much preload if the heads have been planed. Always a good idea to check
If the heads have been planed, then its much more likely for them to be running excessive preload. Definitely not the best thing to do performance-wise, not sure if it has an impact on reliability... though I wouldnt be surprised to hear that it did. One thing thats for sure is that excessive preload wont have the same obvious warning signs as minimal (or no preload) does. No clacking valvetrain! Thats probably why it often goes unnoticed.

thatsmrmastercraft
10-06-2011, 05:43 PM
Hogwash. Id be interested in hearing your rationale for how a set of heads and intake dont stress an engine, but a cam will. All 3 parts do the same darn thing- improve the engine's breathing. If the engine is in good shape, then upgrading the top end is just fine. No need to "freshen up" an engine that doesnt need it.


Just how much hp do you think you can add to a 20 year old engine before you start having problems?

TRBenj
10-06-2011, 06:09 PM
Just how much hp do you think you can add to a 20 year old engine before you start having problems?
Clearly I dont think that adding 80hp in the manner described will cause problems, right? We're still talking ultra conservative modifications, in the big scheme of things. Still a ways below the 1hp/ci mark.

Im curious exactly why you think adding hp will correspond to a decrease in reliability. We're not talking huge changes in operating RPM and stressing parts more. By upgrading the top end parts, its simply able to pump air in and out more efficiently.

The P heads when installed on an Explorer/Mountaineer 302 made a peasly 210hp. By your logic, those motors would have been more reliable than ours simply due to the lower hp output?

What exactly is it about age (you mention 20 yrs old) that makes an engine become less reliable? I figured it would have more to do with the number of hours an engine sees (metal parts wearing out), or lack of proper maintenance that would cause issues.

gr82bgreen
10-06-2011, 06:57 PM
If the heads have been planed, then its much more likely for them to be running excessive preload. Definitely not the best thing to do performance-wise, not sure if it has an impact on reliability... though I wouldnt be surprised to hear that it did. One thing thats for sure is that excessive preload wont have the same obvious warning signs as minimal (or no preload) does. No clacking valvetrain! Thats probably why it often goes unnoticed.

the symptom you COULD have with excessive preload is a valve not fully closing and resulting in compression loss and likley burning the valve quite quickly.

j.mccreight@hotmail.com
10-06-2011, 07:13 PM
Clearly I dont think that adding 80hp in the manner described will cause problems, right? We're still talking ultra conservative modifications, in the big scheme of things. Still a ways below the 1hp/ci mark.

Im curious exactly why you think adding hp will correspond to a decrease in reliability. We're not talking huge changes in operating RPM and stressing parts more. By upgrading the top end parts, its simply able to pump air in and out more efficiently.

The P heads when installed on an Explorer/Mountaineer 302 made a peasly 210hp. By your logic, those motors would have been more reliable than ours simply due to the lower hp output?

What exactly is it about age (you mention 20 yrs old) that makes an engine become less reliable? I figured it would have more to do with the number of hours an engine sees (metal parts wearing out), or lack of proper maintenance that would cause issues.

You claim 350 hp out of your 1990 351w, Whats your setup?

1redTA
10-06-2011, 10:01 PM
a big problem of changing the cam on a "seasoned" engine is the buildup of crud that may be loosened into the oiling system when changing the cam, the amount of wear in the cam bearings and not changing atleast the lifters and springs

riggsy3
10-06-2011, 11:39 PM
Everybody's situation is different to varying degrees, for me yes I could yank my engine out and give it the full treatment (its in the budget), however, the original problem was a crack in the water jacket on port head and not repairable. Once I got the head off and could not locate a suitable match to the starboard head it was game-on i.e. I have lots of options, but I've decided to put the P heads on and leave everything else stock and go. My 20 year old engine ran pretty strong even with the crack in the head. If in the future another major engine component fails then I will give it a total rebuild.

This forum has been very helpful and I'm grateful for the responders opinions and advice.
Thank you.

TRBenj
10-07-2011, 01:17 PM
You claim 350 hp out of your 1990 351w, Whats your setup?
GT40p's, stealth intake, .490/.490 cam, roller rockers, HEI ignition, shorty header style SS exhaust manifolds, 3.5" straight pipes. Basically the standard 320hp 351w (H/C/I with p-heads) upgrade, with a bit more flow on the exhaust and a hotter spark.

a big problem of changing the cam on a "seasoned" engine is the buildup of crud that may be loosened into the oiling system when changing the cam, the amount of wear in the cam bearings and not changing atleast the lifters and springs
Im not sure what sort of "crud" you would expect to release into the oiling system with a cam change that you wouldnt see with a head change. I actually wouldnt expect to dislodge any "crud" in either case with a properly maintained engine. I saw no evidence of any such thing on my 1100+ hr engine when I upgraded the top end.

Im not sure how the wear on the cam bearings comes into play... its there whether you replace the cam or not.

Totally agree on the lifters- you gotta replace them with new ones any time you put in a new (flat tappet) cam.

Gotta disagree on the springs though... if theyre good, theyre good- no problem reusing them, assuming they support the amount of lift the cam/rockers will be throwing at them. No need to go overboard with excessive spring pressure though.

TRBenj
10-07-2011, 01:22 PM
Everybody's situation is different to varying degrees, for me yes I could yank my engine out and give it the full treatment (its in the budget), however, the original problem was a crack in the water jacket on port head and not repairable. Once I got the head off and could not locate a suitable match to the starboard head it was game-on i.e. I have lots of options, but I've decided to put the P heads on and leave everything else stock and go. My 20 year old engine ran pretty strong even with the crack in the head. If in the future another major engine component fails then I will give it a total rebuild.

This forum has been very helpful and I'm grateful for the responders opinions and advice.
Thank you.
I think youre going in the right direction based on your budget and your goals.

Im always after more power, so since the cam change and intake upgrade could have been done for minimal extra cash (youre already replacing the gaskets) then I probably would have done so. If youre happy with the power of the stock engine though, the P heads alone will give you a nice boost.

I see absolutely no problem with replacing the old heads with fresh P heads and going back to skiing. Theyre very cheap to buy (barely any more expensive than a good valve job on the lousy stock heads), and will give you a nice 30-40 more hp to boot.