Best upgrade for 4 barrel 351? Or do prop?

[Bimmerboyz]

The motor was rebuilt a few years ago and it has a Edlebrock intake manifold.

I was wondering what to do as the engine is out to replace the flywheel?

Should I do a mallory ignition system or points are good?

Get the head port and polished?

I don't want to get too expensive.

Or I could do a prop.

I just want more hole shot when I add wait for wakeboarding.

[Andrew]

i'd pick something that requires the engine to be pulled since you already have it out.....

[Rick]

I would do electronic ignition for reliability and Prop for the holeshot $125 for the Pertronix ignition and a prop with 2" less pitch for 325.00.

[Bimmerboyz]

I don't know if it has to come all the way out can't I just slide it forward?

Also I want the best bang for the buck upgrade.

[Bimmerboyz]

I would do electronic ignition for reliability and Prop for the holeshot $125 for the Pertronix ignition and a prop with 2" less pitch for 325.00.

I have 2 props right now I need to know what is the best pitch to use?
If I do end up buyin one should I get a 4 blade or not needed?

[AirTool]

Others can tell you what prop. Here is a link to save you about a hundred bucks.

http://www.planetnautique.com/index.php?name=PNphpBB2&file=viewtopic&t=13423&hig hlight=delta+discount

If you work on your engine I'd put a cam in and do some valve/head work. A cam might suffice and you won't have to pull the heads. You could also change to roller rockers so you'll never have to worry about your lobes wearing down.

Without really working over your engine and replacing a bunch or parts that are still in great shape, a low-end performance cam would be the best bang for buck.

Plus, you'd be the only boat in the tie up with a loped idle like a hot-rodded 69 Mach 1.

AirTool

[TRBenj]

Ive done every single upgrade mentioned here and I can tell you that the best bang for your buck mod out there is a new prop, hands down.

In my opinion, I wouldnt bother with an electronic ignition conversion kit for any amount of money- especially the Pertronix. Ive found points to be very reliable, start great when tuned properly, and cheap! If you want to modify the motor, get a full electronic ignition system (distributor) instead of a conversion kit. If you absolutely have to go EI for whatever reason, stick with Mallory E-Spark or PCM/Prestolite and avoid the Pertronix.

None of the engine modifications mentioned require pulling the engine out. A head/cam/intake upgrade will really improve overall performance, but I would do it all in one shot. Expect to spend ~$1500 to do it right.

Again, I recommend you just go with a new prop and call it a day. If its for your '78, then an Acme 540 will really wake it up- holehot, midrange acceleration, speed holding and smoothness will all improve. Top end may get a slight boost as well. I wouldnt go with a 4-blade as the modern 3-blades outperform them.

[AirTool]

None of the engine modifications mentioned require pulling the engine out. A head/cam/intake upgrade will really improve overall performance, but I would do it all in one shot. Expect to spend ~$1500 to do it right.


Agree on the prop. Also a clarification on head work. If the heads are brought back to new or even better, and the rings are old and worn, the engine will then smoke/burn oil because the old rings won't be able to hold the compression properly and ultimately properly wipe/replace oil.

Usually, if you do one thing on a worn engine, you have to do it all.

Agree you don't have to pull the engine to do that work but you'll save a lot of trips in and out of the boat and won't make such a mess. Assumption was the engine was out to replace the flywheel.

[Andrew]

the ONLY reason that I would say a prop isn't your best "bang for the buck" is if the current prop is ideal or close to..... it would definitely warrant some research!

[AirTool]

Agree with Andrew on the prop. I assumed you had the wrong or old non-cnc prop and improving is possible.


The motor was rebuilt a few years ago and it has a Edlebrock intake manifold.

I read this the first time but then forgot. Sounds like improving inhalation won't cause you ring problems.

I still vote for the cam and roller rockers. Don't mess with the heads. A head job (don't start) would be a little more bang for a lot more buck.

[Bimmerboyz]

Again, I recommend you just go with a new prop and call it a day. If its for your '78, then an Acme 540 will really wake it up- holehot, midrange acceleration, speed holding and smoothness will all improve. Top end may get a slight boost as well. I wouldnt go with a 4-blade as the modern 3-blades outperform them.

I have a amce prop box that I believe my spare prop is in 540 rings a bell I will have to check when I get it out of storage. So I hope and I might have a 540 already. Cam and head work might be the route I take if I have the 540.

[bobchris]

. If the heads are brought back to new or even better, and the rings are old and worn, the engine will then smoke/burn oil because the old rings won't be able to hold the compression properly and ultimately properly wipe/replace oil.


a standard valve grind will not change the compression so it's not going to burn any more oil than it all ready does, Now if the heads are warped and need decked then yes there is a slight increase in compression but usually not enought to change the comrepssion more than .1 and you still won't burn any more or less oil.

Set of GT-40p's is the best bang for the buck even without a cam change for this application.

[AirTool]

. If the heads are brought back to new or even better, and the rings are old and worn, the engine will then smoke/burn oil because the old rings won't be able to hold the compression properly and ultimately properly wipe/replace oil.


a standard valve grind will not change the compression so it's not going to burn any more oil than it all ready does, Now if the heads are warped and need decked then yes there is a slight increase in compression but usually not enought to change the comrepssion more than .1 and you still won't burn any more or less oil.

Set of GT-40p's is the best bang for the buck even without a cam change for this application.

Fixing valve problems will increase compression. Not the theororetical ratio but the actual pressure achieved in compression stroke and during combustion.

It's not about whether the valve grind is special or standard. It is about the condition of the valves, seats, guides, gaskets, and rings prior to fixing said problems with the valves, seats, guides, or gaskets and NOT bringing worn rings back in spec. Compression pressure and combustion pressure are going to increase....especially if some change was made to allow more CFM and fuel to flow into the cylinders on intake stroke. The latter would be the primary reason one would change the cam and work the valves. A secondary reason would be to change valve timing.

Nevertheless, bringing all that pressure back up to or exceeding the spec and having worn out rings is going to be a problem. Fixing head problems without fixing the cylinders and replacing rings or vice versa is a no no. Sure some have done it...but only to sell it. Be sure to watch out for high crankcase pressure and PCV oil entrainment problems.

Besides, he said his rings were good.

[Bimmerboyz]

Set of GT-40p's is the best bang for the buck even without a cam change for this application.

That is around 2500 to do and they have to drill and tap for those heads. If it was slightly cheaper I would go that route.

[SNobsessed]

I think you can get GT40p heads from Clearwater Cylinder for under $700.

[Bimmerboyz]

I can't seem to locate them on that website.

[rosconole]

I drive past clearwater cylinder head about everyday...if anyone needs some heads done I can probably say you some $ on freight.

[Bimmerboyz]

Can you help me out with freight :mrgreen:





J/K

[81nautique]

Don't waste a dime on the stock heads, if you're already runninga 540 then the next upgrade would be the gt40p heads. You can pick a set up for under $500 if you look around. New cam can be found from Cam research, custom ski boat grind # 270 seems to be their popular choice and is what I run. If you don't want to change the cam then go roller rockers at 1.7 ratio and that will bump up the stock cam specs. If you replace the stock rockers with 1.6 rollers you are wasting $200. Go to CCfan and research 351 upgrades, you will find enough to make your head spin. Also agree with trbenj on the ignition, the electronic upgrades don't get you anything but good starting, no noticable performance improvements, I would go with a full electronic unit but it's not neccessary for you right now.

[Bimmerboyz]

SO I got my boat out of storage and it's in my garage now.

My question is I have 2 props the one on it is a 542 13 x 11.5 1" and my spare is a 540 13 x 12 v 1"

Which one is better?

[8122pbrainard]

SO I got my boat out of storage and it's in my garage now.

My question is I have 2 props the one on it is a 542 13 x 11.5 1" and my spare is a 540 13 x 12 v 1"

Which one is better?

It all depends on the use of the boat! 542 will give you a slightly better hole shot plus will be better keeping th rpm's at the sweet spot for boarding. The 540 on the other hand is great for skiing.

[Yooper-Sully]

Definitely do a prop upgrade. Your better off setting the boat up for how you ride, if your putting ballast in an old boat a prop would fall under the Preventative Maintenance group.

[horkn]

fwiw, I got a set of used gt40p heads from a 5.0 explorer, had them decked, springs checked, valves checked, brass freeze plugs, bolt holes drilled out to fit the 351, new valve seals, and a full top end marine gasket kit for $600.

That's bang for your buck.

[bobchris]

fwiw, I got a set of used gt40p heads from a 5.0 explorer, had them decked, springs checked, valves checked, brass freeze plugs, bolt holes drilled out to fit the 351, new valve seals, and a full top end marine gasket kit for $600.

That's bang for your buck.

why waist time looking for heads and hoping the local guys knows what the **** he's doing, for that price you can get them all ready reworked and ready to bolt on for that same price and you don't have to wait on the machine shop either.


1.7 rockers and new heads and cam are the next step up the performance ladder, all for about a grand and that will get you in the 50mph+ club.

But if you don't want to listen to the people that have all ready done all this and know the gains, then your lose.

[horkn]

why waist time looking for heads and hoping the local guys knows what the **** he's doing, for that price you can get them all ready reworked and ready to bolt on for that same price and you don't have to wait on the machine shop either.


1.7 rockers and new heads and cam are the next step up the performance ladder, all for about a grand and that will get you in the 50mph+ club.

But if you don't want to listen to the people that have all ready done all this and know the gains, then your lose.


Well, I don't know if you saw it, but that price included the full top end Fel Pro gasket kit with both head gaskets and all the other top end gaskets specifically for my PCM motor. That alone was around 100 dollars If I recall correctly. Add the cost into the heads from tri state or elsewhere, along with shipping 2 heavy 50 lb + boxes to where you are if you get them from a non local place. Also, had my used heads not needed decking, the cost would have been even less. As I see it, my short amount of time I had to wait was well worth the $150-200 that heads from elsewhere would have run with gaskets and shipping. That amount of $$ is hardly a waste of my time, considering my original heads were totally fine.

I know the machine shop where I had my heads done, they do great work, and are very reputable. However, if you don't have such a good shop locally, then maybe tri state and more money is the route you should go. I will say that tri state has a great deal, I just got an even better one. Price a pair of gt40 (not even the better P heads) from DIM or so and you will be in shock.

[bobchris]

Well, I don't know if you saw it, but that price included the full top end Fel Pro gasket kit with both head gaskets and all the other top end gaskets specifically for my PCM motor. That alone was around 100 dollars If I recall correctly. Add the cost into the heads from tri state or elsewhere, along with shipping 2 heavy 50 lb + boxes to where you are if you get them from a non local place. Also, had my used heads not needed decking, the cost would have been even less. As I see it, my short amount of time I had to wait was well worth the $150-200 that heads from elsewhere would have run with gaskets and shipping. That amount of $$ is hardly a waste of my time, considering my original heads were totally fine.

I know the machine shop where I had my heads done, they do great work, and are very reputable. However, if you don't have such a good shop locally, then maybe tri state and more money is the route you should go. I will say that tri state has a great deal, I just got an even better one. Price a pair of gt40 (not even the better P heads) from DIM or so and you will be in shock.


but what it lacks are spring travel for a high lift cam, undercut stems on the valves, and the unknow you get with used heads, so you can spend the same amount of money and have all new valves, seals, hardend seats, springs and retainers verus used springs and retainers that will have varing spring loads due to the age, old valves that do not have undercut steams with old seats that wil vary the push rod lengths enough that the pedastol will need shimed. So you got lucky and no valve were burnt, so for a big question mark by pulling parts off a used motor verses the know quality of something that is all ready done Tri-State is the safer cheaper route to go. Also the marine head gaskets are thicker too compared to automotive. So if you really want to get junk yard heads you should be looking for D0OE heads anyway and have them massaged and they'll out flow your GT40's all day long.

[pj]

The gt40p's from Tri-State are remans. Hence the cheaper price than new from someplace like SkiDIM

[horkn]

but what it lacks are spring travel for a high lift cam, undercut stems on the valves, and the unknow you get with used heads, so you can spend the same amount of money and have all new valves, seals, hardend seats, springs and retainers verus used springs and retainers that will have varing spring loads due to the age, old valves that do not have undercut steams with old seats that wil vary the push rod lengths enough that the pedastol will need shimed. So you got lucky and no valve were burnt, so for a big question mark by pulling parts off a used motor verses the know quality of something that is all ready done Tri-State is the safer cheaper route to go. Also the marine head gaskets are thicker too compared to automotive. So if you really want to get junk yard heads you should be looking for D0OE heads anyway and have them massaged and they'll out flow your GT40's all day long.


Valve stems were under cut, the springs are the same as the ones from tri state. The proper valve seals are in place as well. Tri state and the automotive machine shop I went to don't do anything differently. The shop I went to was very familiar with PCM and indmar marine motors. If they were not familiar with marine motors, I could see a reason for some trepidation.



I have the original set of heads from my boat, they are D80E heads that I am selling. I have no need to have them ported since the boat has a lot more power as it is with the edelbrock performer manifold and the gt40P heads.

The heads from tri state are used as well, probably old automotive heads just like I got and refurbished.

[horkn]

The gt40p's from Tri-State are remans. Hence the cheaper price than new from someplace like SkiDIM



That and the gt40's that DIM sells are new old stock (NOS), and not as good of a performing head as the GT40P's.

[bobchris]

Valve stems were under cut, the springs are the same as the ones from tri state. The proper valve seals are in place as well. Tri state and the automotive machine shop I went to don't do anything differently. .



I doubt that. So what your telling me is your machine shop replaced all of the valves and all of the springs? about 300 in parts alone, factory heads do not have undercut stems for the valves? Do you even have a clue what I am talking about? doubt it based on your comments, Did your machine shop replace all of the valve springs? doubt that they did most shop rarely replace teh springs or valves unless they are broke or burnt or they are requested to be changed out, Tri state uses a better than stock spring to allow for a higher lift cam that you not going to get with stock springs. Same crap comes out of your mouth on CCF too. Your not the bright IMHO I would never let you around an engine.

[horkn]

I doubt that. So what your telling me is your machine shop replaced all of the valves and all of the springs? about 300 in parts alone, factory heads do not have undercut stems for the valves? Do you even have a clue what I am talking about? doubt it based on your comments, Did your machine shop replace all of the valve springs? doubt that they did most shop rarely replace teh springs or valves unless they are broke or burnt or they are requested to be changed out, Tri state uses a better than stock spring to allow for a higher lift cam that you not going to get with stock springs. Same crap comes out of your mouth on CCF too. Your not the bright IMHO I would never let you around an engine.


I don't know who you are on CCF (and I don't care either), but I can tell you that I know a lot more than you think that I do. I wonder if PN mods will get after you for being derogatory? I know on most forums out there, they don't tolerate garbage like this.