Low budget OMC twin project

[sWaltsu]

Hello

this is my extremely low budget motor / boat project.

I had bought couple broken OMC motors. Old 50hp with BIG electric shifting gearcase. Second motor is 1982 60hp.

First motor (old fifty) was overheating and piston was melted. Gear case is full to water...

Second motor is better.
I will replace just piston rings, seals and gaskets.

Because motor is opened. I might lightly modify it.

change reed valves to fiber model, clean all flow path and increase cylinder compression.

52451
cylinder holes must be modify!

52452
exhaustpipe must be shorten ;)

all bearings is OK. But how fast i can run it, with standard connecting rod, pistons and crankshaft?
6000RPM must be ok, but how it take over 6500RPM?
How much i dare to set ignition timing (degrees)


This just purpose to learn to get more power to propeller.

Two motor, boat and lot of building parts, was cost less than 300 USD.

any ideas what else i must do, to get more power?

Setup:
52453
Gear case (2.4:1 ratio)

52454
four blade "home-made" Cleaver (23")

52455
hull without deck.

--- My other projects---

Bat 22 offshore (http://www.boatracingfacts.com/forums/showthread.php?14930-Project-Bat-22&p=126531#post126531)
and
and homepages: homepages (http://http://vauhtiveneily.fi/)

[Fastjeff57]

Got two complete (but disassembled) 50/ 60 hp OMC power heads if you need any parts. Just pay shipping.

Jeff

[calvin]

Is there any difference between the 50 and 60 hp..or is it just prop shaft vs powerhead hp?

[Fastjeff57]

Porting! The 60 hp has far more aggressive porting.


Jeff

[calvin]

I would love to hace the 60 but need a short shaft with trim and tilt.

[Fastjeff57]

Sorry, the FREE lower unit I have for you is a long shaft.

Jeff

[sWaltsu]

Thank´s, Jeff your offer. But shipping is too difficulty.

My short shaft works only with electric gear case. that´s why i must use long shaft.

Can anybody say, how much i can take off that cylinder head.
We use 98 octane gasoline (Now it might says E10 gasoline. 10% ethanol and 90% gasoline).

And how much i can take RPM, with original crankshaft etc?

Today i get new piston rings. Tomorrow starts cylinder porting (Port and polish)

[LakeRacer99]

Thank´s, Jeff your offer. But shipping is too difficulty.

My short shaft works only with electric gear case. that´s why i must use long shaft.


I'm 98% sure you can make that short mid work with a shifting lower unit. I have both, but have not converted one, but I plan to one day if needed.

Kinda hard to jump out of the gate modifing the motor. how do you learn if you helped it or not? My favorite reply is to get it running, dialed in with available power, then start your mods-especially porting.

[sWaltsu]

52482

Problem to use short shaft. is in the picture. part number 29.

Short shaft model is not hole to gear shaft.
Because electric gear case have only two wires.

[LakeRacer99]

52482

Problem to use short shaft. is in the picture. part number 29.

Short shaft model is not hole to gear shaft.
Because electric gear case have only two wires.

I can't see your attachments...I remember thinking it would not be hard to add the hole. much easier than finding a short mid.

[sWaltsu]

problem is way to get gear shifting rod.

Long shaft model. the way is like pipe. Old, short shaft was only a bolt.
it is very hard to drill hole in the middle on the bolt.

52493
short shaft model this part no hole ;)

52494


But we dont take a problem for it...
Ai will use that longshaft ;)

Today i get piston rings. ;)

next week starts block porting and other boat cockpit project.
52495

[Bill Gohr]

What hes trying to say is the vertical steering tube is solid on the electric shift and the mechanical shift is hollow because the shift rod goes through it, just take the pivot shaft of the short shaft and drill it, or take the pivot shaft out of the long shaft shorten it and install it in the shorty.

[Fastjeff57]

Could someone explain to me how that OMC electric shift worked? I've eyeballed diagrams of it but don't see what's going on.


Thanks,

Merc man Jeff

[LittleCharger]

Porting! The 60 hp has far more aggressive porting.


Jeff

I believe the porting is the same for the 50hp and 60hp blocks for 81 through say 85, this is essentially the same porting as the sst45.

[LittleCharger]

And how much i can take RPM, with original crankshaft etc?



sst45 guys turn over 7k, you might want to put fresh bearings in while you have it apart.

[LakeRacer99]

What hes trying to say is the vertical steering tube is solid on the electric shift and the mechanical shift is hollow because the shift rod goes through it, just take the pivot shaft of the short shaft and drill it, or take the pivot shaft out of the long shaft shorten it and install it in the shorty.

correct, thanks bill...i don't think I have any apart or I would post pics. To me its easier to do that than find or pay what people want for a short Stinger mid.

[LittleCharger]

correct, thanks bill...i don't think I have any apart or I would post pics. To me its easier to do that than find or pay what people want for a short Stinger mid.

The short mid for the two banger is not the same as the short stinger mid, they are usually easier to find and cheaper.

[LakeRacer99]

The short mid for the two banger is not the same as the short stinger mid, they are usually easier to find and cheaper.

Sorry, I thought we were talking about 3cyl. But the info works for them also.