How fast would you expect to go?

[freeisforme]

Today a buddy that's been tinkering with an older Sportcraft, about a 1966 or so model, 15 1/2" long, closed bow hull, came over for me to mount up a used 60hp twin he bought. The boat has a 20" transom but because of the stepped hull at the rear, I chose to mount it a hole higher than normal. The boat has a HP recommendation plate on the transom stating that the recommended horsepower is 65 to 130hp.
I hung the motor, hooked up the controls, hooked up the antique cable steering, and fired it up. The motor sounded good so down to the water we go.
Figuring that the boat with two big guys and 12 gallons of gas and two batteries would weight upwards of 1600 lbs or so, I was only expecting it to do about 25 mph or so. To my surprise it felt much faster. So back to the dock I go, grabbed my GPS, and gave it a check.
The GPS read 43.7 MPH at about 3/4 throttle. The prop pitch is too low, so it will over rev easy, but even so, at 5,500 RPM it's over 40 mph? The boat hull is heavy, without the motor, two of us couldn't lift the bow or stern on the trailer, and it's listed at something like 1210 lbs in the owners manual.

It jumps up on plane fast, and takes right off, far better than it did with it's original motor, which was a 90hp Mercury inline 6. With the old motor, it was a dog, slow to get out of the hole, hard to keep on plane, and terrible on fuel. I wasn't expecting the smaller motor to run this well.

I ran it for about 15 or so miles, it barely moved the fuel level in the tank. The old Merc would have swallowed up nearly 1/4 tank or so.

I've got no clue as to where the motor came from or what it really is other than the model and hood match and say it's a 60hp 1986 20" shaft length motor. It sounds louder than my 55hp that I run on my boat, it's raspier and quicker to accelerate. It sounds like a big dirt bike more than an outboard.
It's got a new water pump kit, supposedly has a rebuilt lower unit, has 145 psi compression, and a rebuilt carb. The head has been off and the all gaskets look new. Is there something that could have been done to this to gain a little extra HP? It idles great, is a little rough through the lower mid range, and hums nicely at higher RPM.

I'm wondering if a higher pitch prop will gain me speed or lose speed and acceleration? Since it's not mine, I don't want to leave it where the motor can be over revved so easy. It would easily rev well over 6,000 RPM the way it is. It doesn't seem to gain much over 5,500 RPM in speed, not as much as it gains in speed between 4,800 and 5,200 RPM.

The boat handles great, the motor runs at a normal temp, no overheating, and it didn't blow out the prop at any point. All of which were concerns since the anti cavitation plate sits about 2" above the bottom of the transom, which is already stepped about 3" compared to the rest of the bottom of the hull.

I've run many OMC 50 to 60hp twins over the years, and never had one run this fast on this size boat. Even on my old aluminum boat, a 16' hull, I never got much over 34 mph on the GPS. What has me thinking is that this may still have more speed if I play with the prop diameter and pitch.

Does anyone have anything similar out there with some real numbers to compare to? I'm sort of wandering here what I did right or what I did wrong?

 

[5150abf]

Re: How fast would you expect to go?

I have a 16' aluminum that doesn't weigh anything close to that with a 50 and got 29.1 last week with the current.

Certainly sounds like someone hopped it up along the way, with the correct prop you would lose some hole shot but should gain even more speed on top.

bored out,shaved heads, polished intakes and bigger carbs I could see getting another 10 or so horse out of it.

 

[jay_merrill]

Re: How fast would you expect to go?

If the motor isn't running hot or cavitating at the current mounting position, I wouldn't worry about the situation. Check the WOT range for the motor against the actual rpm at WOT and adjust pitch with a different prop, accordingly. Expect about a 200 rpm rpm change, for every inch in pitch change.

If the GPS says the boat is going 43 mph, I suspect that it is .... unless you are checking it running down a river or riding a fast, outgoing tide. Remember that a GPS measures speed over the bottom, not speed through the water.



???

 

[freeisforme]

Re: How fast would you expect to go?

If the motor isn't running hot or cavitating at the current mounting position, I wouldn't worry about the situation. Check the WOT range for the motor against the actual rpm at WOT and adjust pitch with a different prop, accordingly. Expect about a 200 rpm rpm change, for every inch in pitch change.

If the GPS says the boat is going 43 mph, I suspect that it is .... unless you are checking it running down a river or riding a fast, outgoing tide. Remember that a GPS measures speed over the bottom, not speed through the water.



???

The current prop is a 11 1/2" x15P. I looked at several prop calculators and all seem to come up with a 11 3/4" x 17p prop, I'm leaning towards one more step up in pitch if I can find on.

I checked speed in both directions, with and against the running tide, I got 46.1 this morning with the tide in the river, 42.2 against the tide but with a 5 knot tail wind.
It's really a fun boat, I just never expected that motor to pull like this.
The carb is different than the one on mine, but I just figured its a different year. It's also one of those motors that fires up at the bump of the key, choke or no choke, it just wants to run. It also doesn't stall, even at a low idle regardless of temperature. The motor is running cool, I can place my hand on the cylinder head after a long run and it's just warm, not hot enough to have to let go. I'm also thinking that the boat could do with a smaller fuel tank, maybe just a six gallon in place of the flat 12 gallon, and it really don't need the group 27 battery to start the motor, a lighter, smaller battery would work fine, the same for the accessory battery up front.

Something else that I didn't think of was that I took all the speed readings standing up looking over the windshield, not sitting down below it. A lot of the buoys were out of place and I was a bit concerned about floating debris.

I found out today that the guy that had this motor raced mini hydroplanes, so that alone has me really thinking as to what was done to it. The first thing I noticed was the exhaust note this thing has and how crisp or raspy the exhaust sounds. It really sounds like a dirt bike when you twist the throttle sharply. It's a bit loud in the water but not bad.

As far as the motor mounting height, I chose the second set of holes because it looked to me that if the motor wasn't in the fully retracted position, that the anti-cavitation plate would be pointed below the hull, or sort of scooping water so to speak. I've always found that having it slightly higher works better than level or below the transom bottom.

I also wonder how much the stepped hull has to do with this things speed?
Looking at the boat on the trailer, it looks pretty low sided but didn't feel that way in the water, that rear step portion of the hull sits level with the water line when afloat and no one aboard. At rest, the anti-cavitation plate is sitting about 1/2" above the water. The minute you hit the throttle, the plate drops down just below the water. It's got a good pee stream at all times and makes a very flat wake.

It used to be my boat and I sold it since I didn't like the way it handled with the 6 cylinder Merc on it, no prop or height combo seemed to work. The boat sat low in the water, was sluggish out of the hole and seemed to plow through the water. A sudden stop would all but swamp the boat from the stern. We were thinking that the 90 hp Merc wasn't enough power. Yet now with a 60hp twin it's a whole different boat.

 

[jay_merrill]

Re: How fast would you expect to go?

I would worry less about the speed at this point and more about whether or not the motor is correctly propped for the boat. To figure this out, we need the specific make/model/year of the motor (to look up manufacturer's recommended WOT range) and the actual rpm that the motor turns at WOT, on this specific boat.

If you need to test the boat to figure out the current WOT rpm, do a couple of runs at the lightest load that you expect to run it, the average load and the heaviest load. If you don't feel like doing three sets of runs, go for the average load.

Once we know what the current WOT rpm is, plus the recommended WOT (which will probaly be a range of about 1,000 rpm between the lower number and the higher number), we can figure out what to do, prop-wise.

If the motor has been tweaked by someone who knows what he is doing, it might well be putting out more HP than if stock. What you don't know, is how radical the person got with the mods. If he went nuts and balanced the crank, connecting rods and pistons, you might be able to safely operate the motor at quite a bit over the recommended max rpm. Most folks wouldn't do that, however, so I would want to be careful of your currrent max rpm. If you have more power than you expected and "not enough prop" (meaning too little pitch), you could be over-revving the motor and risking damage.

Let's try to get your prop right for the boat and worry about the other stuff later.



???

 

[freeisforme]

Re: How fast would you expect to go?

I agree 100%. But I've not been able to get a WOT RPM in fear of damaging the motor. I've only run as far as about 3/4 throttle so far, and at that point I'm over 6400 RPM and gaining RPM fast. I backed down and have been keeping it at about 5,000 to 5,500 RPM tops. The motor is a mix of years, it mostly appears to be a 1985 or so 60HP Johnson twin cylinder.
No VRO unit, a single carb, but not the same carb that's on any of my personal 50 or 55 hp motors, and the flywheel seems to have been machined, it looks like material was taken off the top in fresh cut grooves. The lower unit has Synthetic Oil Only written on it in black marker. There was no prop with the motor, the one on it was a spare I had just to use as a starting point. Its unmarked but appears to be an 11 1/2x15P. The motor has two aftermarket coils, two removable automotive type plug wires, and will start if you spin the flywheel with just the palm of your hand. The compression is normal, in the 140 range so I doubt the head was shaved or anything like that. When I first fired the motor up I used a short rope and no controls, I fired it up in a barrel outside the garage, I was surprised at how easy a motor that was just slid out of the back of a pickup truck looking like a junk yard put together would fire up.
There are some part numbers scribbled on the inside of the cowl, B-124 reeds, Wiseco 3111-P2, the spark plugs are IWF22 Nippondenso, and there's a module that I've not seen before buy CDI, and there's a list of CDI part numbers listed as well inside the cowl. It appears that the harness, stator, power pack, coil, rectifier, and all are CDI built units.
How much else isn't stock I can't say.

It gives me the impression that it'll rev till it pops. I didn't dare push it any faster for that reason. I did seem to hit a rev limiter when I first took off with it, it jumped up on plane quick and when I first goosed the throttle to see what it would do, it shot out of the hole fast and was probably going faster than the max speed I stated but I glanced down at the tach as I let off the throttle and it was coming down to 6500. It either hit an electronic rev limiter or ran out of fuel at higher RPM.
I was really expecting this thing to need full throttle to get up and going, not for it to take off like that. There's a shallow area past the launch area where you need to be on plane to safely cross over some old stumps, otherwise you need to be super careful going out that way. The boat doesn't yet have a depth finder so I wasn't taking any chances although the water was pretty high. It's more a habit to be on plane before that point than a necessity but I've always felt better safe than sorry.

I at this point am thinking that I need to make a bigger than 2 pitch jump in prop size to get a real starting point. The problem will be finding a prop that fits this bill to borrow. The highest pitch I have is a 11 3/4" x 17P which I doubt is a big enough jump.

His buying this motor was a mistake, I told him to look for a 65 to 75hp triple for this boat, he came back with this motor. The odd part is that this is faster than my 70hp is on my 17' aluminum boat even with the wrong prop.
The owner of the boat is not at all mechanically inclined and has little to no boat experience. So making this a bit slower won't hurt either. The way it is now, he'll likely get into trouble or blow the motor.

I also don't feel the prop is slipping or blowing out at all, it seems to maintain a firm bite at all times. At no point does the tach shoot up without an increase in speed as well.

The speeds and RPM achieved were with two 300lb men in the boat, 12 gallons of gas, two group 27 batteries, and two wood framed back to back fold down seats. The hull is a 1965 Sportcraft Ski King Runabout rigged from when new with a ski loop around the motor. The original owners manual lists the hull as being 943 lbs dry net weight. Here's a link I found to a 1966 model, the boat looks about the same other than the windshield and dash area. The 1965 has a dual pod style dash, much shorter and rounded off, sort of made to look like an old Corvette dash I guess, and the '65 has a wrap around one piece windshield with an aluminum frame. The weight is also listed a bit lower on the 1966, so I can't say what else changed but the general idea is the same.
http://www.fiberglassics.com/wiki/images/f/f1/BHBPHOTO112.JPG

 

[jay_merrill]

Re: How fast would you expect to go?

If the motor wants to push through 6,400 rpm easily, see if you can find a 19" prop to try. Many outboard motor dealers will let you test a couple of different props, if you intend to buy one eventually.

Also, look for the freeze plug on the powerhead, we might be able to figure out the model and year from the serial and/or model number. From there, should be able to nail down the correct WOT range.



???

 

[freeisforme]

Re: How fast would you expect to go?

The freeze plug is blank, the tag is gone off the bracket, and the bracket is blue anyhow, the rest is mostly white or gray parts. The cover looks like an 1984 Johnson, the electronics from CDI according to their website are 1985 only.
The lower unit is blue, but repainted white. The sweet spot is around 5600 RPM, at that RPM the motor seems most at home, it's not laboring at all and not screaming, and it sort of quiets down and smooths out if you know what I mean. Of course, if the prop isn't balanced right that too will affect the feel of the motor. It'll cruise all day long at about 38 mph with the motor backed down to about 4700 and change. I ran it there for a few miles yesterday just to put some time on the motor. He got this motor pretty cheap, under $400 turn key.
It isn't pretty but runs good.

I was pretty much thinking that red line is somewhere between 5,800 and 6,000 RPMs but that's a guess.
I'd have to say it's mostly a 1985 motor, but who knows what's inside it.

 

[The Hammer]

Re: How fast would you expect to go?

I'd be tempted to send the Merc over to that guy for a tune up!

 

[jay_merrill]

Re: How fast would you expect to go?

I can't find info on the net as to your WOT range. Assuming that the powerhead is a 1985, its probably 4,500 rpm to 5,500 rpm. You should call an Evinrude dealer to confirm this. Guessing is not a good idea.

The rev limiting that you experienced was most likely being caused by the powerpack. Since you have the part numbers printed on the inside of the cowl, look up yours to see if the sales info states that it is a rev limiting powerpack. I'd take a guess that it is.



???

 

[freeisforme]

Re: How fast would you expect to go?

I've got a 1983 50hp Evinrude, and a 1978 55hp Johnson of my own, both have a redline of 6,000 RPM in the owners manual. Both are basically the same motor.
However I rarely push those above 5,000 RPM simply because I have no need to go any faster. Neither will hit more than 5850 RPM at WOT the way they're propped. Neither move as fast though as this 60hp does though, I've owned both for years and both are in mint condition, they both sound nothing like this 60hp.
I finally got some info on the 60hp from the guy he bought it from. The last owner used it on a small hydroplane, he said that the only thing he changed to sell it was the lower unit since the lower they use has all the fins and AV plate ground off and no neutral or reverse. He says the pistons are custom made Wiseco pistons, something he modified to his own liking but he wouldn't say how or what he did. The block is ported and polished but he said he's not sure how much of an improvement that makes as he didn't see any major changes, and the electronics are basically stock but he replaced everything as a whole from CDI Electronics. He said if it was hitting what felt like a rev limiter it was most likely closer to 7200 RPM and to check my tach.
I use a Snap on tach that reads off one plug wire, as well as a built in tach on the boat, both matched fine. He claims to have sold the motor for $800 not the $400 I was told by the owner too, but that's neither here nor there.
The crank is aftermarket, he named a company but it didn't ring any bells and I got the impression that they just take OEM cranks and improve upon them somehow. He said he runs a motor for a season and builds another to stay competitive. This one was his first motor, built from many used motors.

I asked what he felt the rev limit was and to him, there is none, he said "It'll run out of fuel before it comes apart". Maybe that's what I was feeling, not a rev limiter but a lack of fuel at higher RPM. He said the carbs come from a larger motor, but wasn't sure what they were off of.
The carbs are attached to the control cable by means of a home made bellcrank which in turn pulls a shorter cable attached to the carb linkage. All of the linkage is made from tiny Hyme joints and thread rods.

He said the lower unit they run uses a shear pin prop not through the exhaust, so I take it the whole lower unit is customized somehow for that.
Either way, no matter how it was set up before its on a stock mid and lower now. One of the first things I noticed when I first saw this motor is it's lack of a hollow steer tube, the tilt pin is nearly solid with only a 1/2 or so hole down through the middle with threads going through the middle and two shimmed bolts adjusting the free play. Luckily this boat still uses rope and pulley steering.

I'll call around on Monday and see if anyone has a 19P prop on hand to try, I sort of doubt it though. It seems a tall order for one of these motors.

When this thing is running it sounds like a radical big cc dirt bike, not an outboard. It's almost a shame to see it being used on a boat that'll most likely never do more than go few miles here and there to go fishing.
(I'd love to see this thing on a super light aluminum hull!).

It sounds good to me running around 5,000 RPM, I can't imagine the WOT rating being less than that on a looper twin, let alone taking into account any aftermarket mods that are in it. If it were me running the boat, I'd probably jump up to a 17P prop, and just run it at 5,000 to 5,200 RPM and consider that my top speed. Keep in mind that this is basically a 45 year old 15' glass boat built for two that's nearing 50mph. I doubt that any motor hung on it back in 1965 would get it much over 35 mph or so.
While it handles well at higher speed, I can feel it getting a bit loose on curves, It slides a bit into high speed curves, any faster and I'd fear a spin out if pushed to corner too hard. I messed around a bit at 42 mph to see how hard and how sharp I could make the bends in one river here and it barely makes the turn at that speed, the lack of a keel or any lateral form on the hull when fully up on plane gives it very little side to side control. The motor alone is steering the boat. The fact that the boats owner is an elderly man with near no power boat experience is at least some cause for concern.
With him aboard, he didn't see anything wrong with my pushing it into the curves like that to see how well it hung on. He kept standing up and walking around the boat. My guess will be that he'll do one of two things, either never run the boat fast enough to get on plane or else he'll be the type to hop in and run wide open all the time not realizing that the motor will push the boat to possibly unsafe speeds. Also being that this is still rope and pulley steered, it takes several turns of the wheel to make the boat turn, unlike a Teleflex system, which only takes a turn or three lock to lock. This takes 7 turns each way to make a full hard turn.

Something else I noticed today that's odd is that reverse has very little effect on this boat. I nearly have to run full throttle to get it to respond to reverse. It reminds me of trying to back up a tunnel drive boat.
I'm not sure if this is due to the motor being an inch high, or because of the stepped hull design? I'll move pretty good in forward even at idle, yet not move in reverse at or even slightly above idle. Reverse lifts the back of the boat when you throttle up. I figure that the stream of water off the prop is deflecting downward off the step in the hull?

Seeing this, I also wonder how much the shape of this hull has to do with the prop and engine RPM?

 

[freeisforme]

Re: How fast would you expect to go?

A short update, I found a 11 3/4" x 18p prop to try, but it reacted so bad to the change I got very little info from the test on the water. The 18P prop made it noticeably slower to get on plane, and it's slow to gain speed now. When it did get up past 28 mph, it started to blow out the prop or loose it's grip on the water so to speak. I had to add throttle so gingerly that I ran out of room to get up to full speed. I figured maybe that the higher mounting position was now an issue but lowering the motor made things worse.
For now I went back to the 15P prop. I have a 17P out at a prop shop now being re-hubbed and cupped for another boat, that'll be the next one I try.
The 18P was a brand new stock prop, nothing ever done to it. A local dealer that I buy from let me try it.

The blades on that new prop looked different than those on the one I have on it now, the 18p prop has blades that were more rounded on the end and flat edged, the 15p has more of a flat area at the top of each blade and a small lip on the edges of the blades. The prop on it now is from MW, the one I tried was unmarked other than the size and pitch. The blades on the 15P also stay wider longer before tapering off to the hub where as the 18P clearly had less surface area per blade.

I never got to 30 mph with the 18P, not because the motor maxed out but because the prop kept loosing grip or cavitating I guess. It felt like I was dragging the anchor for the whole ride. I even tried it with less weight and only me aboard and it still acted the same. I went back the 15P and all was back to where it was before with the motor able to over rev.

 

[freeisforme]

Re: How fast would you expect to go?

I'd be tempted to send the Merc over to that guy for a tune up!

The Merc didn't need a tune up, it needed to go on a diet. It was a heavy inline 6 cylinder motor compared to the much lighter Johnson twin cylinder on the boat now.

I transplanted the Merc onto an older Glasspar and on there it does just fine.
It just needed a boat more able to keep the stern afloat higher. The Glasspar was a much lighter hull.

 

[Frank Acampora]

Re: How fast would you expect to go?

My experience with Chrysler and Force engines, which are admittedly old school and modest in power, is that porting adds about 10 HP per cylinder in the larger engines.

However, porting of any engine, while it raises the horsepower, also raises the curve and thus the RPM at which that horsepower is delivered.

Given that your engine is ported and has aftermarket reeds, and given that it has .020 over Wiseco pistons, It is reasonable to expect that it actually maked significantly more than 60 HP.

However (again) If, for example, the factory rated the stock engine at an operating range of 5000-6000 with its rated HP delivered at 5500, porting would negate this. You NEED higher RPM to let the ports work--It is somewhat similar to a high lift comp cam in an automobile: Run the engine slow and it runs like crap. The cam is designed for best performance at higher RPM.

In fact, you would probably want to run the engine signigicantly over 6000 RPM, possibly at 7000. There is not much to worry about until you get radical with RPM. These engines have a short stroke and small pistons, and no reciprocating valve train. They are probably good for at least 8000 RPM without damaging themselves. Understand though that high horsepower and high RPM do equal shorter service life--As an extreme example, look at a dragster. It puts out a couple of thousand horsepower at about 10,000 RPM. Its service life is 5 to 10 seconds.

 

[freeisforme]

Re: How fast would you expect to go?

With the 15p prop, the motor seems to like running around 5,000 RPM or so, it seems to run out of fuel up high, but I haven't held it there long enough to really figure out when it starts to break up. Of coarse, it feels most like a rev limiter than a fuel issue but the Power pack doesn't have a rev limiter feature according to CDI.
My guess is that one of the coils are breaking down at high RPM, I ordered two new coils to be safe. If they don't make any difference, I have two new coils for my motor. The carbs look fine inside, but again, their not from a 60hp motor. I have a set of new take off 60hp carbs I can try too but I doubt they will do the trick.

I'm happy with it making what ever hp is makes, I'm not doing this to gain more speed, I just want to optimize what is here and have it run smoothly.
I'm just shocked at how fast it's going with no tuning at all.

If this had a mechanical throttle stop at say 3/4 throttle, it would run just fine, top out at about 5200 RPM, and never miss a beat and cruise at 42 to 44 mph all day long. If I give it a bit more travel, I'd be up around 48 mph and at 5600 to 5800 RPM or so. It does have a lot more, but I don't want to get near the point where it breaks up, keep in mind that this is an old man's fishing boat. He's been using it all week with the throttle limiter on it, from what I saw, he never gets it much over planing speed and backs off. However, without any RPM control it can really scream during a hard take off. It also starts gaining speed fast if you really push it with no throttle control or stop. The two times I took it up that high, I felt the need to hold and stay in control far more than grabbing the GPS and checking my speed.
It sort of passes the point where that hull feels safe, I'm not sure what it is, but the first symptom is that the it slides sideways on turns. I'm turning the wheel sharper and sharper and the boat is barely responding but yet getting closer to the right side of the channel fast going into the turn. Under about 50 it's fine, with very little of that out of control feel. Over 50, which I'm sure it's at, although I've not held the GPS in hand to verify it, it feels like a car when your on black ice in a big open parking lot just screwing around. It's a bit hard to maintain a strait course, hard to correct and hard to steer.
The physical steering also gets real hard at higher speeds, but there's no steering pull. Also keep in mind this still uses a rope and pulley steering system. The old guy doesn't want to change what works, probably just don't have the money. As it is, this is a favor, not a paying job or anything. I have a lot of spare parts around to play with, and will no doubt be one of those using this boat from time to time, so I have an interest in making it right.

 

[ground_pounder]

Re: How fast would you expect to go?

I don't know much, but it sounds like the basket of parts worked in his favor. Admittedly, I don't know much, but whatever lower ended up on it with the gear ratio in it, and picking a prop off the wall and setting it up on that boat and it all turning out to run good, I wish I had that kind of karma. The guy who built that powerhead must have really knew what he was doing, especially if it still runs after you know it was pushed on a hydroplane. One thing I been thinkin about lately is the motor weight on the transom. My '74 50 horse on my little 16ft tri hull seems to work really good and get up and go and isn't quick, but does 27mph. I've come accross a few 3 and 4 cylinders I could have on hand to repower it, but I imagine that weight and going from a 2 cyl to 3-4 would make my little boat do things different and probably not as good as it handles now. If it at least idles along pretty good sounds about right you just have to be a smarter operator, and save WOT for a good clear shot of fun accross a good size lake. If it was a hotrod, I'd say put a brick under the pedal til you get to the track and don't overdrive your braking, suspension and handling. Sounds like a strong powerhead and a good cobble of stuff thereafter. Like I said, I don't know 2 cycles like I do building car engines, but everything that was done to it probably put the powerband on that up there for WOT or performance on the go, which would make more sence for racing, not fishing hole to fishing hole. If it works though, run with it. My best guess about the piston is he ported it to match, inless he was able to give it a little more stroke with the crank, and had to put in a relief and/or turned the top to take some material out of the top for weight and changing the cc's of what's left at the end of the stroke for combustion, not much different than shaving the head or adding popup pistons to change it to the positive.

 

[ground_pounder]

Re: How fast would you expect to go?

A electric fuel pump might get aome more out of it too, but from the sound of it you want to cool it off than get more out of it. I would be curious that with the fuel consumption being nil, it is built to run leaner than your avg motor. A 460 will get better fuel mileage than a 351 if its geared right and you keep your foot out of it. I would put a timing light on it and record what it is set at, just in case, so you don't have to do it by ear if something has to be replaced. On my 74, I noticed my timing is set with a bump stop at WOT? Might be something to think about, backing off the advance might keep it from winding out. But I'd ask someone who knows, cuz I'm still learning about these beasties and know automotive engines. It could end up running hotter and melt itself into a paperweight if it don't do what I think it does.

 

[ground_pounder]

Re: How fast would you expect to go?

Sorry I keep typing, this is interesting to me though . A stock carb should tone it down I bet, it can't burn what it can't suck in. Hard to say if whatever was done internally would like the mixture of a smaller cfm fixed venturi. The mixture has as much to do with heat dissipation too. I don't think it would affect that the motor, just because it is capable of pumping more, getting a stock like restriction in the intake. I am not sure what the reeds do though either. You hate to mess with what works like you said. The powerhead is built to run, and everything should jive together from intake to exhaust to how the power is put down. If its really cool also, have to wonder if he didn't take the thermostat out and tossed it since it sounds like it don't really need it.

 

[freeisforme]

Re: How fast would you expect to go?

I found out the other day that the guy sold the boat, he bought something else and sold that one to some kid. The kid took the boat out and blew the motor. He came by here with it the other morning, it feels like it lost the lower rod or lower rod bearing, I pulled the head and found bits of bearing embedded in the piston and head, the motor will only turn about a quarter turn. The prop also has a huge gash in it and is missing about 1/3rd of one blade. The kid came right out and told me he removed the stupid throttle stop and the thing ran WAY better, it turned all the way up to 8800 RPM and flew. I told the kid that these things have a red line of about 6,000 RPM, he looked surprised and went on about how his motorcycle could turn 10,000 RPM. The lower unit is also trashed, the skeg is missing a huge chunk, it's seized as well, and the drive shaft is twisted at the splines. The lower unit is also full of water but with all that damage, it's hard to tell what went first. I'd guess he slammed the lower unit into something and then blew the motor as a result of it. I was surprised to see both the power head and lower unit locked up at the same time. When he brought the boat over, there was 6" of water in the hull, the plug was still in it and both seats, which were mint originals were broken. It was a shame to see such an super clean original boat get destroyed after all these years. (That boat went 45 years without so much as a scratch only to have some idiot tear it up in one outing).

The motor is toast, the kid didn't much care as he asked if he could get a new motor put on that boat, something bigger and faster, he's talking about a 100+HP so he can get it to go even faster. (No thermostat, it's got a stainless cup with a hole in the middle in place of the thermostat, not just an open hole).

I sort of figure the boat won't last a week with this guy running it. I guess his daddy has deep pockets.

The guy that sold it bought an aluminum boat that came with a running Mercury 50 on it, bone stock and turn key, I'm not sure why he moved on to another boat other than the new boat is a bow rider vs. a closed bow runabout.

The blown 60hp is laying on a pallet out back behind my garage for now under a tarp. If the kid don't come back for it, I guess its mine for parts. If nothing else, I'll tear it apart out of curiosity. For now though I'm letting it sit till I know what the new owner intends to do with it. I'd be willing to bet I'll never see him again. When I pulled the motor off, he unbolted the controls and cables and tossed those in the scrap pile behind my garage, so he certainly doesn't intend to reuse them. I grabbed them up and put them away, both cables were brand new, as was the ignition switch. I did put the carbs and electronics off that motor under my workbench for safe keeping.

 

[The Hammer]

Re: How fast would you expect to go?

Well you can tie a rope to that old motor and use it for a anchor, doesn't sound like theres any usable parts left. I would suspect the transom to be busted if he hit something that hard.