Re placement engine opinion

[Arkitorture]

Hello, I recently posted about my 1970 Tri Sonic rebuild project from stern drive to outboard. Overall opinion came back don't do it. As for the boat I am pretty much looking at a total rebuild. Yes, it will be a lot of work. Anyway, I will try and get the project posted so everyone can see it and the progress. But before I can start the build back process what Engine should go back into this boat? I would assume a complete transome is going to happen, but would like to know, I don't want a expensive engine if possible. It had a 150 Mercruiser in it. I am gutting the hull and going to repair any damage to the bottom inside and out. Haven't decided if I should tackle re-doint the paint? But I just don't want to build back the boat only to find out that after market engine x,y,z won't fit? Thanks for the advice in advance, Matt

 

[HT32BSX115]

Re: Re placement engine opinion

Hi Matt,


Well if you're bent on rebuilding the boat "for the fun of it" ......that's different....Because it's for recreation it doesn't matter how "hard" a job it is....

I did a little search of Trisonic boats and there's several sizes. If it's got a 150 Mercruiser in it, it might be a little anemic in power if it's 18ft or larger.

If the drive is needing rebuilding, I would probably get a newer gimbal and new SEI drive and couple it up with a 5.7L carbed V-8.

Just about any (1987+ engine/drive is going to "fit"..... Stay away from OMC. Volvo might be just fine if you can find one. There are Mercruisers everywhere.

If you do a search on EBAY, you'll find more Mercruiser parts, drives, engines, etc than anything, 3:1 over anything else.

Check the transom, floor and stringer wood VERY carefully. Most boats that old have rotten floors, stringers and transoms.


Post a pic!


Cheers,



Rick

 

[Arkitorture]

Re: Re placement engine opinion

Rick, the boat is 16' long. I have no idea if the stern drive is any good or not. Seems less work to not use it, but REALLY concern that any new motor is mounted at a correct angle and that the gear shaft will fit correctly?? This is why I am considering replacing both? Also, just want an engine to get me up to 40 mph, a V-8 on my dads V-hule would do about 65. I think it was a 300 hp. Anyway, just a starter boat so even if it only does 25 mph, I have three kids, 6,7,8 and want to see if the family is up to going out on the lake all summer like I did when I grew up.

 

[HT32BSX115]

Re: Re placement engine opinion

For a 16' I would say the good old 3.0 liter Merc would be more than enough for what you want. If it were me, I would keep my eyes open on eBay and Craigslist for a "donor" boat that I could pull the entire drive package from. Around me I see these boats fairly often in the $1000 or less range.

Yeah, I'll agree. In fact, for a 16' boat the 150 Mercruiser would be just fine. I had a 1966 18' Marktwain (Dad bought it new) and it had a 150 Mercruiser. It ran fine for nearly 40 years before I sold it.

You could probably get a 250 cu-in truck engine from a wrecking yard and it would drop in and run just fine (use the marine starter, alt, dist, carb, manifolds etc) OR you could just rebuild the 230 I-6....that would be my choice..... They're great engines.

but REALLY concern that any new motor is mounted at a correct angle and that the gear shaft will fit correctly??

You'll get to that point when you re-install the engine and drive.....but it is taken care of when you align everything. There's a simple procedure for it so don't worry about it...

At some point you will need an OEM service manual for the Mercruiser.

 

[rbh]

Re: Re placement engine opinion

for a 16 foot boat I would also go with a straight four, not overly heavy or over horesed.
rob

 

[HT32BSX115]

Re: Re placement engine opinion

I'll also add that the 230/250 cu=in 6 is probably the smoothest running engine on the water. FAR smoother than any 4 banger....

 

[rbh]

Re: Re placement engine opinion

morning Rick-
in a 16 foot boat, how much weight do you think the engine and leg should be at most?
I would wonder how big of a fuel tank he would need.
rob

 

[HT32BSX115]

Re: Re placement engine opinion

I don't know that it matters for that boat since it came with 150 Mercruiser (230cu-in 6 + Mercruiser #1 drive) new.

A 3.0L engine would absolutely be lighter for similar HP but it would certainly be a lot less expensive to just rebuild the 230 or put a 250 in it and run it.

My 66 Mark Twain had an 18 gallon tank in it for about 35 years.....We used to ski all day with it...