Moesly Seacraft 21 repower opinions

[McGillicuddy]

First of all, I hope y'all on the eastern seaboard survived Matthew with minimal damage. My sister is in JAX and faired pretty well. On the other hand, some friends in Lumberton NC took a beating and are about to lose a dam/levee. God Bless you all.

I'm thinking about re-powering my 21 Moesly for Christmas. Unfortunately, like the Kinks, circa 1979, i'm on a low budget, thus I'm looking for your .02. I took the liberty of dragging sme of Fr. Franks quote over from the earlier I-6 discussion to start an opinion gathering thread for repowering a 21.

Ive been looking for a solid I-6 MC 165, but I think I'd like more top end than 165 can offer and also a fairly efficient cruise ant troll. In that earlier thread, FLexpat mentioned the 292/200 hp set up from FirstMate which sounds appealing. Not sure if the extra 35 ponies gets me much but I'd like to get to 35-40 mph in flat water. In fact its 50 more ponies than right now, as i have a 50 year old 150 mercruiser.

Logic says follow IslandTrader's lead and put a small block gm in there, but I like the idea of keeping the layout original an doing little more than painting the engine cover. using something like 3rdDay's choice of a 400 pound 200 hp on a bracket is also a possibility, I guess. Can you say used 2.6 L Etec? Sure...

Originally Posted by Fr. Frank

[B][I]Mercruiser DID make a 250hp version of this motor for racing purposes...I've only seen two boats with this power setup.
Allmand made a 19' back in 1968 for the offshore racing circuit...powered with a single 250hp 250ci motor. I don't think he ever finished a major race...

Formula made the '69-70 23' with twin 250hp 250ci I-6 Mercruisers and they too, were, in fact, rated at 250hp each... I recall one of the mechanics saying he got it up to 58 mph during "testing".

The thought of getting 200 ponies or better from an I-6 is appealing.

I welcome all thoughts se please, feel free to chime in.

[wattaway2]

You asked for our .02--- how about the 292 you mentioned.Clifford research four barrel intake. get with Holley and I'd bet they could set you up with a throttle body fuel injection system then upgrade to a electronic ignition system and I wouldn't think mercury' 250 hp number would be hard to achieve .you could get with Clifford and see if a cam is needed to match what Mercury was using ?

[FLexpat]

Originally Posted by wattaway2

You asked for our .02--- how about the 292 you mentioned.Clifford research four barrel intake. get with Holley and I'd bet they could set you up with a throttle body fuel injection system then upgrade to a electronic ignition system and I wouldn't think mercury' 250 hp number would be hard to achieve .you could get with Clifford and see if a cam is needed to match what Mercury was using ?

The Clifford intake won't fit with a marine exhaust manifold but I think the original intake was set up for a small 4bbl on some of them. That said since a 292 is 4.8l it probably only flows about 350 cfm, a 4bbl is probably a waste of fuel - the more modern marine 2bbl from a 5.0 will flow about the right amount of air and be a bit more efficient - it might fit the existing intake. I would worry about reversion of water if the cam got too 'hi performance' or someone did not understand the difference between a marine cam and a performance cam - maybe work the head to make it higher flow/more efficient instead? Crowley will do custom cam grinds and match it with roller lifters but I don't know if they know what the marine cam is. A rebuilt mercruiser long block with marine cam is 2200 from Perfomance Pro (reselling for FirstMate).

[McGillicuddy]

Originally Posted by wattaway2

You asked for our .02--- how about the 292 you mentioned.Clifford research four barrel intake. get with Holley and I'd bet they could set you up with a throttle body fuel injection system then upgrade
to a electronic ignition system and I wouldn't think mercury' 250 hp number would be hard to achieve .you could get with Clifford and see if a cam is needed to match what Mercury was using ?

Thanks, wattaway. I am very intrigued by the gm 292 idea. What about the sterndrive? Any insight on compatibility? My understanding was Merc only mated it to a Mercruiser II. Do you know of requirements to to make it adaptable to more current drives like Alpha, Bravo, SEI? Simple as a transom plate and gimbal housing? Would it require a particular gear ratio? I'm very excited to learn more.

[Bushwacker]

Hey Gillie,

What sort of WOT are you getting with the 150? Don't know what Bob Reiland's WOT was with the original 150 MC in the Moesly 21 "Unohu", but once he learned about the importance of using a vacuum gage and observing a limit of 5-7" Hg for max continuous/cruise power for decent exhaust valve life, he was limited to cruise speeds of about 18 kts. However Bob's friends said he ALWAYS ran 18 knots back then, regardless of sea conditions, so he kinda liked it when seas got up to around 4-6', when few other boats could stay up with him! The last engine he had in it was a 290 hp/350 Chevy/Volvo outdrive, and he said it was a 50 mph rig, although it was also thirstier than the 260 MC! Too bad he passed away a few months ago, as I'm sure he could give you some good advice on how much power you need to get the speed you want! You might also send a PM to Carla, as I'm sure Carl would know that answer!

There's no substitute for cubic inches, so I'd do some research on that 292 block and the Clifford Research site! Is there any way to install the OHC Pontiac head on the 292? With an aluminum head, you'd have to add FWC, so not sure if it would be worth the extra complexity. It's easy to soup up an engine with a hot cam and bigger carb, but doing that usually trades mid-range torque for high end HP and a rough idle, so not always what you want for marine use. A V-8 would certainly meet your WOT speed goals, but a well built 292 (ported head with a good 3 angle valve job and possibly oversize valves, Stellite valve seats, positive valve rotators, and file-fit rings for min gap/leakdown) might develop a surprising amount of HP while still making for a simple installation and easy maintenance. Only question would be how the cost of that would compare to a stock V-8 + boat mods. I suspect the V-8 might actually be a cheaper and simpler route if you could do the boat mods yourself.

Besides cylinder head airflow capacity, the camshaft is the key item for making power. If they make roller cams for that motor, that allows you to open the valves quicker with more lift for more "area under the curve" and more airflow/power without going too wild on duration that would screw up mid-range torque and idle quality. This would be a marine/RV type cam grind as opposed to a race grind that's often used on roller cams. It might also require solid lifters, so you'd also have to be willing to adjust valve lash occasionally, but that's not too hard once you learn to do it. Fuel injection really won't add any power relative to a properly set up carb. It might improve starting and idle operation, but it will require more sensors and be much harder to set up. I think a mildly "breathed on" I-6 and a more modern Alpha drive would be a unique and easily maintained set-up that could offer surprising performance if done right! Keep us posted on what you find out! Denny

[McGillicuddy]

Thanks Denny, I really appreciate the insight. WOT feels like 30 mph or less at 3900 rpm... Original tach, so sketchy at best. Seafari quickly does 36 mph and that feeling of speed is there. That nimble quickness is not there in the 21. Of course it's a lot heftier and I really haven't spent the time or effort to dial it in. The seafari is dialed in with a solid 115 tower, goes w/o saying. very different animals.

I'm not really wanting to hop it up just seeking I6 reliability and a sense of giddy up if necessary. I'd love to see 40mph or so cuz the hull deserves it, but I don't think I'd be inclined to spend a big wad of cash on a hot cam or carb to gain 2-3 knots on top end. Most of the time I would be cruising 15-20 knots or less searching for fish offshore.

I want consistent and absolute control @ low idle for trolling and docking and the inherent low and midrange torque of the I6 on plane. I want to preserve Carl's balance fore and aft, and to keep the original engine cover. I really like the original layout, although truth is l really lack Brian and Terry's discipline and motivation skills to do fantastic restorations like theirs.

[Bushwacker]

You may be over propped if the tach is accurate (if you could find a strobe light type tach, that would be a good way to check it), as I'd think you should be turning at least 4500, so a larger dia prop with less pitch might spin faster and give you a better hole shot with about the same top end. Bob used to easily cruise at 20 kts at about 9" vacuum with a Bahamas load with the 260 hp MC, which was perfect for following him in my Seafari with the 115 on it, although I had to wind it up to 4500 to stay with him. I'm sure he could have cruised at 25-28 kts if he wanted to. Might touch base with Island Trader to see how much you'd have to mod the deck and engine box to install a V-8. The Chevy V-8's are so common that you can almost buy parts at the corner drug store, so it may actually be cheaper to run a stock V-8 than trying to find an I-6 that's been out of production for years. The weight difference/balance shouldn't be much different.

Data from Carla's website indicates that the 21 would run 40 mph with a 225 hp MC. I'm guessing that was probably a 327 cu. in. V-8.

[wattaway2]

Did a lil research as you got my curiosity up --don think the intake will work do to the wet exhaust manifolds . Looked at Barrs site and looks like the manifold has the intake and exhaust combine dint one unit . It does look like a carb adapter is used that might allow for use of the Holley 2bbl throttle body injection . A buddy used there(small 650 cfm unit ) on a healthy 360 mopar greatly improving his idle speed and fuel economy and overall performance . They make a "lump" to install in the cylinder heads intake ports to improve the air flow redirecting the air for a better angle approaching the valve I found very interesting

[SandlapperGT]

What would you anticipate the performance with a 300hp outboard or twin 200 outboards?

Good luck with the re-power.....

[jtharmo]

Originally Posted by SandlapperGT

or twin 200 outboards?

Since the door was left open a crack on outboards I was thinking how sweet it would be to go old-school Merc twin towers like many of the classic racing 21's. I see from some of the original literature the 21's were offered with twin 100's or 115's. Sorry no tech but it's nice to imagine.