Thinking of repowering a 1971 Stamas with twin 165's

RichBolduc

Recruit
Joined
Nov 15, 2011
Messages
5
Hi everyone... First post..

I've looked around and haven't found much info on this, but I'm thinking of repowering a 1971 Stamas 26' that has twin 165's in it. I wanted to go with a new motor, but was wondering if there was anything that will drop in without having to do transom work. One person recommended putting in a Mercruiser Magnum with a Bravo 3, but I don't really want to rebuild a transom. Is there any newer 4 or 6 cylinder that I can put in there that will line up with the alpha one's and give me just as much horse power, if not slightly more?


Thanks,
Rich
 

mr 88

Commander
Joined
Nov 3, 2010
Messages
2,126
Re: Thinking of repowering a 1971 Stamas with twin 165's

You might be able to put some V-6 with more hp. I had the same setup on a 73. The hull is rated for 300 or 310[ can't exactly remember what the plate said.] So your at your max hp wise.One V8 350ci would not be enough hp and the gas used would be far greater due to running close to WOT to cruise at 26mphs. Not to mention the transom mess from 2 to 1 NEW out-drive.The 6's sip gas at that speed, two work better than one in this case along with more power with twin drives and the backup factor in case of engine probs while at sea. I would measure the distance from ctr of engine to ctr of other engine.Then I would check measurements of Marine V6 engine.Then do the math to see if they fit.Next thing up is to research the drive ratio on a V6 vs what it is on the 250ci 165hp that you have.You may need new gears or out-drives.I had mine rebuilt and 1 had a cracked block,picked up a replacement at a boneyard. The 250's are great motors in my opinion and unless your craving more speed in a classic cruiser I would rebuild before changing the power plant.I think I got 36mph with a flybridge and early in the season,so the boat was "light" with only me onboard.Had 17" SS Stilletto blades and ran a few hundred under the redline .You may get more response if you post it in the Mercruiser forum.The make of boat does not matter,its all in the dimensions you have to work with including depth of engine on mounting brackets vs distance to floor from oil pan. Just put down for a heading something like,,repowering questions or thinking of swapping out straight 6 vs V6..Good luck
 

RichBolduc

Recruit
Joined
Nov 15, 2011
Messages
5
Re: Thinking of repowering a 1971 Stamas with twin 165's

Thanks for the response. From what you and a bunch of others said, it sounds like rebuilding is the way to go.

I believe the transom is rated for 330hp... How bad would it be if I rebuilt them to 200HP each?

As for the out drives, I plan on replacing the Gen 1's with Gen 2's. What was the model # of your props? I might try them on mine in the meantime.

I plan on using the boat for diving, so I'd like it to do 20-25knots with full gear and 6 people.

Just had an awesome full transom platform built for it and dive ladder too.
 

mr 88

Commander
Joined
Nov 3, 2010
Messages
2,126
Re: Thinking of repowering a 1971 Stamas with twin 165's

I would say rebuilding to a 200h would be okay as quite a bit of the torque should be on the motor mounts and stringers which you should check out.Overly built as well does not hurt the transom factor as well.One way is to check stringers is to check the motor mount Lag bolts holes out after you take the motor out. With the load you talking about 200 and hydraulic trim tabs would be the way to go.But I am no USCG rep so ask around.Need the new power plant and RPM rating in to figure out the prop pitch.Mine were made by Stilleto,17" cupped SS,I would guess you would be around 18-19" with the extra hp and weight, your optimum cruising speed 22kts and around 2mpg or a tad less.
 

ericv26

Seaman Apprentice
Joined
Jun 21, 2013
Messages
43
Re: Thinking of repowering a 1971 Stamas with twin 165's

Any pics of your boat. you are not far from me here in Tampa. we launch up at nicks alot and go out to the sandbar. like seeing other Stamas's whenever possible.just in the middle of rebuilding my 5.7. mine will run 35-36 mph and not too bad on fuel
 
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