Looking for a Inboard guy

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ryanjames170
Posts: 108
Joined: Tue Aug 01, 2017 12:19 am
Location: Hayward WI

Looking for a Inboard guy

Postby ryanjames170 » Sat Aug 12, 2017 10:27 pm

I am wondering if anyone here is also into inboards? I am trading a guy for a chevy 350 engine for a VW TDI I have and I kinds want to build a old school inboard boat.. nothing fast going to limit the engine down from a 4bbl to a 2bbl and 2500RPM vs 4500 or so..

I'm looking for someone who knows about this stuff to get idea of what I'm in for.
Mercury/OMC guy..

3 Merc's
4 johnson's
1 Hiawatha/Gale

outbdnut2
Posts: 487
Joined: Wed Apr 27, 2016 2:46 pm

Re: Looking for a Inboard guy

Postby outbdnut2 » Sun Aug 13, 2017 4:42 pm

I've worked on a few inboards for friends and neighbors, so I know just enough to be dangerous. I also am on my 2nd inboard/outboard that has a 4.3 liter Chevy V6 built up by Mercury for their MerCruiser system. There is a lot more to an inboard engine than just hooking up a car engine, especially where safety in involved. If the motor is going to be in an enclosed space, you will need water-cooled exhaust manifolds and spark arresting air cleaner (the air cleaner is law in most states and with the coastguard). You will need rubber fuel line approved for marine use. Check out how cooling water gets to these inboards too. Most have an impeller and an automotive type water pump. You also need spark-arresting screens on the alternator vents. Need a blower to purge air from the motor enclosure for a couple minutes before starting in case gas vapor has accumulated. Most inboards and inboard/outboards use a 150 degree thermostat. Best if you find a junk inboard boat to donate the drive system, prop, steering with rudder, and other stuff, some of which is mentioned here. If the motor is not covered up, and you are looking at straight out exhaust pipes used in racing, etc., be advised they are illegal due to the sound level.

A lot of today's name brand inboard boats use engines by Pleasure Craft http://www.pleasurecraft.com They build auto engines up for marine use. My neighbor's Ski-Nautique from the 1970s has a Pleasurecraft Ford V8.

Back in the 1950s/1960s, magazines like Popular Mechanics had plans to build many types of boats. These and other plans are available at Glen-L and Clarkcraft, and probably others too. Many of these were inboards. I recommend you look into some published plans and see what all goes into an "old School" inboard. There are kits available too from some of these companies:

http://www.glen-l.com/designs/inboard/inboards.html

http://www.clarkcraft.com

An old school inboard canbe a very cool, fun boat if done right!
Good Luck!
Dave

amuller
Posts: 591
Joined: Tue Jun 14, 2016 12:04 pm

Re: Looking for a Inboard guy

Postby amuller » Sun Aug 13, 2017 11:04 pm

(In Minnesota, at any rate) people are always essentially giving away 4, 6, and V8 stern drive boats. I assume you are planning a straight inboard or v-drive, but a stern drive boat could give you most or all of the stuff needed for a safe and legal marine installation of an auto engine. Manifolds, marine certified electrics, spark arrestor, manifolds, etc. Most Mercruiser stern drives have the raw water pump in the drive, but Volvo-Pentas have it on the engine.

ryanjames170
Posts: 108
Joined: Tue Aug 01, 2017 12:19 am
Location: Hayward WI

Re: Looking for a Inboard guy

Postby ryanjames170 » Sun Aug 13, 2017 11:39 pm

i was thinking on a mid engined beast but if i found a older stern drive not on a fiberglas boat i would consider it.. basicly i want something to cruse in not really go a break neck speed. why im planning to de tune the engine as much as i can. why 2bbl carb and most likely a throttle stop. perhaps a prop that would give enough RPM but not as much forward speed for it..
Mercury/OMC guy..

3 Merc's
4 johnson's
1 Hiawatha/Gale

User avatar
Garry in Tampa
Posts: 2135
Joined: Mon Mar 09, 2015 2:32 pm
Location: Florida

Re: Looking for a Inboard guy

Postby Garry in Tampa » Sun Aug 13, 2017 11:56 pm

Since marine engine always run under load, a truck cam will give you better bottom end. . . ;)
Image

ryanjames170
Posts: 108
Joined: Tue Aug 01, 2017 12:19 am
Location: Hayward WI

Re: Looking for a Inboard guy

Postby ryanjames170 » Mon Aug 14, 2017 12:02 am

i was refering to not lugging it along at 1200 rpm all day.. more in the range of 1800-2500 rpm
Mercury/OMC guy..

3 Merc's
4 johnson's
1 Hiawatha/Gale

amuller
Posts: 591
Joined: Tue Jun 14, 2016 12:04 pm

Re: Looking for a Inboard guy

Postby amuller » Mon Aug 14, 2017 11:04 am

If you want that sort of engine, maybe look for an old Graymarine, Palmer, Universal, etc flathead engine with a mechanical gearbox. These are usually conversions of of Continental, International, etc industrial/tractor engines and run in the speed range you are talking about.

outbdnut2
Posts: 487
Joined: Wed Apr 27, 2016 2:46 pm

Re: Looking for a Inboard guy

Postby outbdnut2 » Mon Aug 14, 2017 11:29 am

You can get creative and modify the throttle linkage back at the carb to limit speed, but if you limit it too much, you may have trouble planeing it off, but your idea of a low pitch prop helps solve that issue. An old school governor on the throttle would give you full power to plane it off, but still limit RPM to a preset number. As for older stern drives not on fiberglass, there are aluminum stern drives out there - Crestliner made several over the years. I've never seen a stern drive on a wood boat.

You may want to avoid the old Johnson I/O stern drives. Word is that they refused to pay Mercury royalties to use their patents and as a result had more complex and less desirable outdrives and power tilt and trim mechanisms. The only positive I can think of on the old Johnson drives was they tilted up a full 90 degrees, getting the prop way high out of the water.
Dave

Dougs Outboards
Posts: 106
Joined: Fri Mar 20, 2015 1:39 pm

Re: Looking for a Inboard guy

Postby Dougs Outboards » Mon Aug 14, 2017 1:04 pm

Also heard somewhere that a regular car engine cannot be used sucessfully. I have been told they need an extra 4 thousants ring end gap, plus marine parts to survive.

Reason given to me is that a boat motor is always pushing, where a car has effort at the start, but since it rolls on wheels, it cruises easily when it gets going, thus easier on the motor without overheating issues.

I actually installed a A130 4 cyl volvo motor out of an old 1960's auto in a bayliner, didn't last too long... nothing but problems for me. Your experience may be different.

ryanjames170
Posts: 108
Joined: Tue Aug 01, 2017 12:19 am
Location: Hayward WI

Re: Looking for a Inboard guy

Postby ryanjames170 » Mon Aug 14, 2017 6:02 pm

I'm kinda getting the 350 for nothing so I figured I might as well use it for something..

I would plan to marenize it as I'm only getting a long block..

Engine is out of a van from the 80s and I'm told it was a replacement engine for this van
Mercury/OMC guy..

3 Merc's
4 johnson's
1 Hiawatha/Gale


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