need help 50hp merc

[Arkansas river rat]

I can't remember what year models but i think they came off of a 3cylinder.I'd have to take another look at the information. Think they were in the late 70's 78 or 79 can't remember. Get to late model and the bolt pattern on the carbs are cross staggered

[Arkansas river rat]

the 70 merc if its a 49 cu in one will fit the 40/45/50 tower housing, You just need the adapter thats below the powerhead is all..
the best machinest around the does the merc blocks is James Ruck, he is in Oshkosh, Wi phone/fax 920-233-3833...He done two of my blocks and they where a awsome work..
good luck with your prodjects

Thanks I've had a few people say it wouldn't fit. I told them everything is the same except the adaptor plate which is different from the 35 to the 70.
Is the 49cu merc and pretty reliable motor? I plan on running it with a jet pump on a 1648 jon. that weighs around 350lbs but i'll lose 1/3 of the power running a jet but 49 or 50 should really push the boat.

[Fastjeff57]

You're talkin' my language! Unlike most Mercophiles out there, I actually LIKE the triples and run one on my little boat. And they are a VERY lightweight package if mounted on a Mark 55 type tower--about 145 lbs. Finally, it is an easy swap to do (once you know how) that does not require a machine shop, just simple tools.

On the triple's propensity to torch its top cylinder--and all 5 triples I've messed with had a bad top cylinder--here's the deal: The water pump used on these motors is too damn small! (The Mark 35A up to the thru-hub triple use the SAME impeller.) Compounding that insanity is that they send part of the desperately needed water flow through the fuel pump! Doh and double doh! I channel ALL of that water to the power head, where it's needed. Finally, the top carb jets need to be at least 2 steps richer than the lower one (which is what Merc did eventually).

Finally, the 65 and 70 hp (60 after the re-rating) triples are much different. The 70 has exhaust ports nearly a quarter inch higher and looses that crappy, unreliable distributor system, so go with that one.

Jeff

Here's a video on mine inaction, mounted on a 9 footer (with a terrible hull!)

http://www.youtube.com/watch?v=1oCSXMSWUEU

[Arkansas river rat]

Your little boat really hauls. I didn't know later model motors would bolt to those midsection.I have alot to learn still. I just recently got into boat motors. I wished i could get my motor that light. Lighter is always better in river running. What do you do to direct all the water to the motor. Is it just a hose you plug or is there a port you have to plug.

[Aeroliner]

http://www.boatracingfacts.com/forum...ead.php?t=6393

This thread covers a number of the modifications. Porting is the simplest but then you can go from there.

Alan

[Fastjeff57]

To put all the water through the power head, just plug where it comes out of the power head adapter on the right side.

Jeff

PS: I even make my own sheet metal base and f-glass cowlings, anything to save weight!

[Aeroliner]

Cowl is very nice. A lot of work goes into making somthing of high quality.
Alan

[Fastjeff57]

Thanks! I kinda HATE those decals, however. Might remove them and try again.

Jeff

[Lil' Blue Rude]

If you port the motor don't use a port map from a prop motor. A jet pump motor needs more torque then a prop motor so the port maps from prop motor don't produce the torque needed. Iv'e always heard people say a prop motor is like a sprint car and a jet motor is like a pulling truck. Most jets turn less then 6000rpms so you need your peak power to be below that.

[clough]

I can't remember what year models but i think they came off of a 3cylinder.I'd have to take another look at the information. Think they were in the late 70's 78 or 79 can't remember. Get to late model and the bolt pattern on the carbs are cross staggered

i dunno man i was looking at some 3cyl 65hp carbs and they seem to be 'stuck together' with a plate not seperate check the pic attached....someone shed some light please and weather 65hp carbs that came on the 65hp 4cyl would do any good on a 44ci merc!? sounds like an easy enough 'hop-up' if you can? info please!

got the pics from : http://www.vintageoutboardparts.com/...roducts_id=891