1971 Merc 1350 - yay or nay?

[thewombis]

Recently purchased a 1980 Hydrostream Vector which I am currently doing a full re-core over the winter. I started searching for an engine, so by the time I get the boat done i'll be ready for the water.

I came across a 1971 inline 6 1350. Was wondering the potential of this motor, and if its worth picking up for $650. (running condition, 132-135psi across all 6) Properly setup, what type of speeds should I be able to obtain if my set goal was around 70-75mph. Do those inline 6's even turn very high revs?

One advantage to the motor is that it would give the boat a nice nostalgic look and feel, but at the same time, I don't want a 12 yr old passing me on a seadoo. :rolleyes: (ps. I am familiar with the chine walk, and learning curve of the
Hydrostreams, just looking for the most bang for the buck at this time..)

Any advice would be great, Thanks!
-Derek

[Michael J Giesler]

my dad's 15' hustler comp wildcat was a 1971 and he had a 1971 135ss motor stock was great boat went high 60's I would get it for that price to go faster 150xs 135's good motors:thumbsup:

[Mark75H]

I agree with Mike, 60's is probably your best speed with an inline 6.

If 70+ is a priority you will need a lot more motor

The motor you describe sounds like a good deal otherwise

[Jeff_G]

Low to mid 60's depending on prop with THAT motor. The 135 was a good engine. I started racing with a 1350.
With the right set up and a later inline 6 like the 1500, 70 is a distinct possibility. You won't need a larger motor than the inline 6 to achieve your goal, but putting a v-6 make is easy to reach, anyone can do it. Here again there are trade offs like more mass higher up, worse handling, heavier weight etc.

[LightNBug]

If the lower unit is original it is a 1.78:1 gear. That means you will need a lot less prop pitch than the 1400 and 1500 which were 2:1. If your boat doesn't end up being too heavy after the rework I think low 70's mph would be realistic if you are willing to spend the money for a good prop in the 14 x 24-26 range. Also keep in mind that many of the parts for this motor are NLA and good mechanics for one are more scarce that parts. When we changed from the 1350 to the 1500 in 1973 on a 15' Allison there was less than 2 mph difference in top speed, but a unbelievable difference in lap times due to the acceleratin difference.

[oldskier]

Wombis, Welcome to the board, You may notice in my sig line, I have a Viper and 1350 but not on the same boat. I bought the Powercat that the inline is on JUST for the 1350, before I knew what a Powercat was. I was going to remove the V6 from the Viper and put the 1350 on it, due to handling issues that I won't get in to here.

I think your Vector/1350 combo would be a great one if you realized the speed limitations the 1350 would impose. If you read about Vipers, Vectors and Vkings here going 100 mph, be aware, that is not your league with an inline.

I am much more impressed with a vintage boat motor combo that has RESPECTABLE speed than a race motor on a pleasure boat. Thats just me.

Also be aware, that 12 year old on the PWC may WELL be capable of 80 MPH with a modern turbo'd motor. If you want to go 80 for cheap, thats what you need. If you want to go 60+ in style, put that inline on your Vector and see who gets the attention at the ramp!

Bernie

BTW, passing ANYTHING made in this century with a 39 year old boat/motor combo is the schtuff for me. In the Powercat with my 1350, (50 mph gps) I can't quit smiling ALL DAY:D:thumbsup:

[thewombis]

The only negative of this motor as I read is that part of the skeg is busted off. I have access for repair, so maybe I can use that as a little ammo to knock the price down a little more.. maybe.

Is there anything else I should pay attention to besides compression, and sounds? (knocks, non typical 2 stroke noises, etc..)

This is not necessary, but I really enjoy the "just above water" exhaust outlets just for there sound value, are these capable of that mod? and I'm not talking about the slackers, those are a little to noisy =)

[bearclaw]

In the 'mid-'70's, I had a '70 Checkmate MX18 with the same year 1350. It was basically an MX15 with a thyroid condition, big but not heavy. I straightened the bottom, blocked up the engine about 3-3/4" (that's all I figured the transom would stand), and started playing with props. Best one I had was a 14" X 24" stainless 2-blade elephant-ear, an old OPC racer special. I could hit 62 - but my distinct recollection is that it took half the lake to get there because of the tall gearing. As we all know that inlines do not like being lugged, and elderly inlines like it even less, that gearing becomes even more of an issue. I also remember that engine being the most sensitive one I've ever had to losing power when the weather was hot and humid. I always figured it was trying so hard to spin to breathe (or vice versa), that anything that impeded that was just compounding the problem. Not my favorite engine? I guess you'd have to say that. For economic reason, you can't go wrong for that price, but a 1400, a 1500, or a newer inline 140 or prop-rated 115 wouldn't be much more and yield better results IMO. Those motors would also be even more period-correct for your boat. :)

With a newer inline, you will reach 70 without going to extraordinary measures.

[Raceman]

First of all, I'd NEVER weld a skeg back on and put it on a V bottom/pad boat that you were going to run the transom height high on and try to get into mid to upper 60's. (I don't think you'll EVER get a Vector to run OVER 65 with a 1350. Also, in addition to what L'nBug said on the gear ratio, that gearcase is the earlier design and blount in front, although it may very well NOT blow out at the speeds a 1350 could push a Vector.

I LOVE inlines......... they're my favorite........... BUT if you're wanting to run 70's and more you're probably better off startin' off with a V6. I think you'd have to blueprint the bottom, get the setup near perfect and have a VERY GOOD blade to reach near 70 with that combination. The exhaust can be livened up a little bit (noise wise) with some strategically placed holes in the gearcase above the cavitation plate. Wouldn't recommend a hole anywhere in the mid section on an inline. Been there, done that, cracked housings.

[thewombis]

I appreciate all your help, from everyone. I have so many questions, and enjoy learning from the best. Another topic I was looking into was use of Jack plates, setback etc. I would love to use a jack plate, but am looking to have the minimum amount of setback. Weather I need one or not, I always thought it would be something to play with, and see different cause and effects it would offer. I guess what I would like to ask is, If you had this boat, what would be a great over all setup? for not only speed, but cruises, play, etc. :thumbsup:

Also, I have thought about blueprinting the hull, but i need to rework a section of bottom which I am dreading. It appears that about a 3' section of gel coat, including the chyne and all have ripped off the starboard side bottom. (rear) I am a perfectionist, and and really hoping to match as close to factory as possible. The other problem is, This same thing happened to the previous owner except on the port side. He did his repair, and it came out "so-so" cosmetically. The pad is virgin, and undamaged, so I was hoping that is the more important areas, rather than to each side. I guess I can only do my best at making it close to factory. Will this be a safty issue when I decide to reach higher speeds?

I will post come pictures.

[oldskier]

In the 'mid-'70's, I had a '70 Checkmate MX18 with the same year 1350. It was basically an MX15 with a thyroid condition, big but not heavy. I straightened the bottom, blocked up the engine about 3-3/4" (that's all I figured the transom would stand), and started playing with props. Best one I had was a 14" X 24" stainless 2-blade elephant-ear, an old OPC racer special. I could hit 62 - but my distinct recollection is that it took half the lake to get there because of the tall gearing. As we all know that inlines do not like being lugged, and elderly inlines like it even less, that gearing becomes even more of an issue. I also remember that engine being the most sensitive one I've ever had to losing power when the weather was hot and humid. I always figured it was trying so hard to spin to breathe (or vice versa), that anything that impeded that was just compounding the problem. Not my favorite engine? I guess you'd have to say that. For economic reason, you can't go wrong for that price, but a 1400, a 1500, or a newer inline 140 or prop-rated 115 wouldn't be much more and yield better results IMO. Those motors would also be even more period-correct for your boat. :)

With a newer inline, you will reach 70 without going to extraordinary measures.

What RPM was it spinning at 62? Maybe a smaller wheel would have helped. 2 blades ain't the 'state of the art' now or even then. From what I have read, mid 6k's are very sustainable with these engines.

Wombis,The lower could be replaced, thought I needed one and had a couple offered to me at reasonable prices here on Snf. "Fixed" skegs are a questionalbe subject here, if you do it, make sure the guy welding it didn't just graduate from welding class at the local tech school.

What else to look for? The wiring insulation under the cowl will probably have the insulation deteriorated to the consistency of dried oatmeal. Thats pretty normal for the older Mercs. If you can't handle the rewire, you'll need someone who can. The fuel lines if original, should be replaced with new ones, the ethanol in modern fuel will have started eating them up from the inside, and the carbs will need cleaning, fuel pump diaphragms will need replaced and the impeller replaced.

The exhaust you are talking about is called 'offshore'... probably because you can hear them from WAYYY out there. Never seen one on an inline but I bet others here have.

[bearclaw]

What RPM was it spinning at 62? Maybe a smaller wheel would have helped. 2 blades ain't the 'state of the art' now or even then. From what I have read, mid 6k's are very sustainable with these engines.

We're talking 34-35 years ago - but I believe it was right around 6000-6100. I did squeeze 63 mph out of it when everything was "just right", but then that was on a Keller so who knows :). I know back then I would not have looked to turn it much higher. We generally thought the 6500 range were reserved for the guys we know who raced, or someone only looking to own short-term. Maybe some knew better then, but I didn't. I even started with a 22" Merc Hi-Po bronze, which actually worked pretty darned well. I tried a couple Italian props I got ahold of, then the 24". Remember that in '74, that 2-blade was the weapon of choice for many FJ & SJ guys (check old photos). A friend of mine got a 3-blade "offshore" (prototype for the Choppers) for his Viper in '75, this was the first I remember seeing one on a lake boat.

[Raceman]

.......................................................but i need to rework a section of bottom which I am dreading. It appears that about a 3' section of gel coat, including the chyne and all have ripped off the starboard side bottom. (rear) I am a perfectionist, and and really hoping to match as close to factory as possible. The other problem is, This same thing happened to the previous owner except on the port side. He did his repair, and it came out "so-so" cosmetically. The pad is virgin, and undamaged, so I was hoping that is the more important areas, rather than to each side. I guess I can only do my best at making it close to factory. Will this be a safty issue when I decide to reach higher speeds?

I will post come pictures.

Old Hydrostreams are NOTORIOUS for delaminating BECAUSE the coring they used in the bottoms gets wet. They weren't well sealed in the floors when they were build. Based on the fact that it's delamed twice (and the fact that 90% or more of the older Streams REQUIRE recoring) there's a pretty good chance that's what you're looking at. You can bang around under the boat with a rubber mallet and listen for changes in the "thud".

[thewombis]

Oh, the rotted balsa is 100% confirmed, when i picked up the boat, the guy said he installed a new floor after his repairs to the port side. He also mentioned this was his first fiberglass repair, so at that moment i knew i was planning on ripping out his old floor. Believe it or not, i had pulled chunks of rusted "I" beam out of the stringer. Yes, Rusted steel I beams.. I'm pretty content on re-doing the core using balsa, and plan on taking every precaution to do it properly to seal water out. As well as making my own knees, and stringers for extra support, while keeping it light. Its a project for sure.

[Jeff_G]

Little off subject but get yourself about 5 or 6 2X4's. Cut them to about 6' long. Glue them together. Take the whole deal to a wood shop and have them planed absolutely true.
Put them under the pad in your boat on jack stands.
When you cut out your floor and grind out the coring the bottom will be soft and flexible. The 2X4's will keep the pad flat until you get new stringers and coring in and you will have a lot less work when you turn the bottom over to do the bottom work.