Newbie Engine Questions

About inboard or outboard motors.

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mrintense
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Newbie Engine Questions

Post by mrintense »

I've been researching engine options for my forthcoming Vera Cruise build and trying to find answers has been a challenge. So I am hoping that perhaps some of those answers can be found here. In the meantime, I will keep looking.

Please bear with me.

The Vera Cruise is designed for an outboard but has the option of an I/O drive up to 700lbs. This is my preference as of right now (although I have not made a final decision yet).

From what I have been able to find out, the Mercruiser engine choice for this weight range is the 3.0 Liter Mercruiser 4 cylinder rated at around 135 HP at 4400-4800 rpm. From the material available in the site and from the Glen Witt book on inboards I've determined this means that it should be approx 95 shaft horsepower at around 3200 RPM. The Vera Cruise notes state a range of 32 to 125 SHP for a boat weighing approx 3800 lbs.

This would seem to mean that the 3.0 liter is the correct choice assuming I can keep my boats weight close to the given figures. Am I making the correct assumptions here?


The other question has more to do with building but the question is relevant since it involves mounting the engine.

Basically, the I/O option calls for motor stringers to be included in the structure of the boat.These motor stringers need to be the correct distance apart in order to properly mount the engine. This would seem to indicate that I am going to have to buy the engine early in the building cycle in order to know how far apart to install the stringers. I am sure others have considered this question so I would be interested in hearing thoughts on this.

Since I planned to pay as I go on this build, having to shell out a large chunk of money early on could mean a serious setback for my building plans. I am hoping that perhaps there are some standard measurements available or perhaps templates.

Thanks for any input on this. I am really looking forward to getting started but I need to answer some of these basic questions first.
Carl

Crafting a classically styled Vera Cruise

Clipper Boating

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Caber-Feidh
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Re: Newbie Engine Questions

Post by Caber-Feidh »

If I remember right the 140 is mounted to 2 ears on the transom ring, and a single 2-point pylon in the front. Stringers do not bear the engine.
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slug
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Re: Newbie Engine Questions

Post by slug »

Not sure on this engine, but most marine engine packages will provide technical drawings with measurements for the boat builders and designers. You might try looking for this on the manufacturer's web site.

Doug

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kens
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Re: Newbie Engine Questions

Post by kens »

I think your math is on the right track. You should get the installation drawings from Mercruiser for that engine setup. The smaller mercruisers don't mount to stringers per-se. They have a 2-bolt mount ears on bell housing with a pedestal mount on front.
Remember that the thrust of the outdrive pushes against the transom, and the stringers only support the engine weight. there is a special tool for alignment of the u-joint for correct installation also.
The mercruiser installation drawings will show how you need to build the stringers/mounts/etc. merc should specify the exact weight as well.
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Bill Edmundson
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Re: Newbie Engine Questions

Post by Bill Edmundson »

All this other stuff being accepted. Stringers are usually set 26" apart inside face to inside face.

Bill
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Mr Hot Rod
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Re: Newbie Engine Questions

Post by Mr Hot Rod »

The following links might help :
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Kane Custom Boats Ltd.
Chelsea, Quebec

Building the Glen-L Hot Rod : http://www.kanecustomboats.com

Glen-L Boat Video Directory : http://www.kanecustomboats.com/pages/vi ... ctory.html

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mrintense
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Re: Newbie Engine Questions

Post by mrintense »

Thanks to all who replied. Good answers here. I don't know why I didn't think to check with Mercury for installation docs. I went there straight away and found what I need.

However, a question I neglected to ask in the previous post was whether the 95 SHP is adequate for this design. Having no previous experience with boats puts me at a disadvantage. 95 horses seems low to me but it does fall in the middle of the recommended range for the design. I looked at the 4.3L Merc (6 cylinder) but it appears that it exceeds the weight limit of 700 pounds. I would gain approximately 40 horsepower using that engine.

With the 3.0 I'm concerned that the engine may have to work too hard and it won't hold up.

As for building, well, all I need are the plans! :?
Carl

Crafting a classically styled Vera Cruise

Clipper Boating

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kens
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Re: Newbie Engine Questions

Post by kens »

the boats on this forum don't need as much power as one might expect. if that 3.0L falls in the middle of the power curve, then it will perform fine, that is, if the builder completes the project within the weight and specs of the plans.
My boat is 25 foot and gets up and planes on 80hp.
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

Craig Aho
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Re: Newbie Engine Questions

Post by Craig Aho »

This looks like a good place to ask my engine questions. I will be looking for a used motor for my Sea Knight and would like feedback, should I only consider 4 strock if I want to be able to use the boat on lakes as well as the Puget Sound. Are there any 2 stocks that I should consider. I would like to have a 50-70 HP motor. Cost will be a factor. Thank you for any opinions.

Craig

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Lowka53
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Re: Newbie Engine Questions

Post by Lowka53 »

8) try local paper in classified on line also check ebay. allot of us look and buy downer boat to get motors and other parts. there are other places on web to get new and used rebuilt motors as well :lol: :wink:
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matt167
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Re: Newbie Engine Questions

Post by matt167 »

2 stroke oil is cheap. If your going to be running it where you may need to buy more gas out of a marina, just carry a few bottles of marine/ outboard 2 stroke oil. Evinrude/ Johnson are usually dead reliable, Mercury's are fast, but not the most reliable

Old saying, If you want to get there first, buy a merc, if you want to get there and back, buy an Evinrude

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galamb
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Re: Newbie Engine Questions

Post by galamb »

Be very careful if you are looking at "used" 4 stroke outboards. Unlike their 2 stroke predecessors they don't take kindly to "lack of maintenance". When a 4 stroke is a year or two old it needs a full "going over" which includes valve adjustments etc.

From experience I can tell you that is "seldom" done by the average boat owner. A complete service runs into the many hundreds of dollars and since most boats are simply used the occassional weekend (and the owners are already "tapped" from making the "easy" 120 payments to own the new toy they don't use much), they rarely get the attention they need.

For that reason I would stay away from "private" sales. Pay the premium and get it (used) from a dealer and ONLY if they include at least a 6 month warranty.

On the flip side of that - most 2 strokes can be rehabilitated fairly easily even if they have been sitting for a bit. It will still cost you money, but nowhere near their 4 stroke cousins.

On ANY used outboard figure on the following: complete tune up (new plugs, maybe coils, clean/adjust the carbs or professionally clean the injectors), water pump service, gear case pressure test and new oil. If you can do this yourself you can get away with a couple hundred bucks worth of parts, if not, figure on upwards of 1000 bucks to get a 5+ year old outboard "fit" - it could be less, but often isn't (eg. a carb service is about 200 bucks for the first carb and 150 for all others after in a multi-carb set-up, a water pump kit can run upwards of 100 bucks plus labour) - after all, it's not for sale because it's perfect - if it was it wouldn't be for sale.

So depending what you are looking at, sometimes "new" is not really expensive given the alternative, especially in the mid-range horse motors that you mention - do your homework, ask opinions - there are lots of good used models out there and there are some obsolete "dogs"...
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Craig Aho
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Re: Newbie Engine Questions

Post by Craig Aho »

Thanks for the replys. I have to admit I,m still smitten with the Bearcat 55, it just seems like a nice motor and apparently well liked by those that own them. They are available rebuilt for about 1600 and are reported to be extreamly reliable and easy on gas etc. The 55 hp would be fine for my boat and expected use. Last year I talked with Mr. Witt and I mentioned my desire for about 70-75hp for my Sea Knight and his comment was "It doesnt need that much power". Any comments about the Homelite/Bearcat motor?

Thanks again
Craig

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galamb
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Re: Newbie Engine Questions

Post by galamb »

Bearcats (and Homelites which were their sister model) are nice old - (stopped production in the early 70's I think - originally marketed by Boston Whaler) motors that would look "good" on a classic style wooden hull.

On the positive side:

they are 4 cylinders and they are a fourstroke (built when nobody was making a 4 stroke outboard) - so they will run smooth

they have a displacement of almost 60 cubic inches (motors that have a displacement greater than their horsepower rating will last a very long time)

they had quite a loyal following and parts are still quite readily available for most maint items you might need (waterpump, carbs etc)

The neither good/bad -

they weigh in at about 240 pounds - close to most 50'ish horse 2 strokes which are generally in the 200 lb class and a little less than modern 4 strokes which usually tip the scales in the 250-260 pound range

the early Homelite versions had a corrosion problem in the lower units (caused by exhaust gasses overheating the foot). The Bearcat models changed the waterflow channels a bit and alleviated this problem.

(I'm looking through "notes" here my dad passed along - I don't have a factory manual)

these were rated in Brake Horsepower (BHP) which is about 10% less than Shaft Horsepower, which is how motors are rated today (since about the mid 1980's) - so it put's out about 50 horses by todays standards - but they do look cool (I have a 1963 Gale, 40 horse, and you can't beat that look on the back of a wooden runabout)

The (maybe) bad -

the mfg called for these to burn "premium" gasoline (92 octane minimum), and they would have burned "leaded" gas. I have less than limited experience with these (my father worked on one in his shop quite a number of years ago and I only remember it because he pointed out it was a 4 stroke), so can't give an opinion as to how they perform on unleaded (potential issues) or if a lead substitute is required

the carbs are old Tillotson's. Tillotson no longer makes outboard carbs and parts are getting scarce (Merc kits for old Tillotson's are no longer "complete" because certain needle valves and seats have just plain run out) - so while kits are still currently available for these, they may not be in 5 or 10 years (???)

BUT, back to a positive here, there is an aftermarket company out there (the name escapes me now - make parts for a number of old classics - Gale, McCulloch, etc) that builds electric fuel pumps and electronic ignitions for Bearcats, so they can be modernized to some extent while keeping the classic look (If you don't mind opening the wallet a bit) :)
Graham

Yes, Plywood is "real" wood :)

A "professional" is someone who gets paid for their work - it doesn't necessarily mean they are good at it :)

Craig Aho
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Re: Newbie Engine Questions

Post by Craig Aho »

Thank You Graham for the excellent feedback.

Craig

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