OutBoard performace?

[adam98]

I have 115 1969 johnson and was woundering if there are and mods like porting, reeds, jetting, milled heads, or anything worth pointing out besides raising the motor or adding a transform spacer jack plate or different props. I understand people just want there boats to run but everything can run better right? what are most these motors looking for or lacking

i might tear it apart this winter and take it to my engine builder to see what he thinks. or is it a waste of effort?

 

[Solittle]

Re: OutBoard performace?

You said "is it a waste of effort?" Yes if you are concerned about the bucks. No if you want to do it for the hell of it.

 

[Silvertip]

Re: OutBoard performace?

Trying to hot rod a 1969 outboard is a terrible waste of money. Spend it on a newer motor of the same HP and get better performance and fuel economy in the process. Outboards are typically tuned near the upper limits of their capability for reliable operation. If you look at displacement only, most manufacturers have two, three and even four engine horsepower ratings using the same basic displacement. So the lower horsepower engines in that group can, with a fair amount of money be brought to the next HP up. However, the highest HP engine in that displacement group is pretty well at the top of its capability. Can y0u get more out of it? Certainly -- how much money do you have? Can you deal with reduced reliability? How much performance increase do you think you can achieve? For the money spent, not much but all of that depends on the boat that engine is mounted on.

 

[adam98]

Re: OutBoard performace?

Thanks for the input and that makes sense.
I come from motorcycle Performance and old models generally have lots of room for easy porting or milling... But I will leave this motor alone and take your word for it, thanks again

 

[boat2fast]

Re: OutBoard performace?

Power trim is necessary for operating a performance oriented boat/motor. 1969 through 1972 OMC outboards did not have a power trim option. Power 'tilt' was available but this is only for beaching, trailing, and shallow water idling. Starting in 1973 you had the twin cylinder trim for these motors. These are getting hard to find in good condition(expensive). Starting in 1978 you had the units used all the way up to 1990. These are easier and cheaper to find and these later engines probably already have them. Later engines are a better choice for powerhead options as well.
Why modify a good engine? No reason I can see, unless you are seriously racing. John/Evin V4 engines run great just like they are.
* prop to allow full rated rpms. Don't over-prop and lug a V4, get's em hot & makes them ping.
* Run carbon guard at regular intervals and run engine tuner(removes carbon)once in a while.
* Keep fuel system clean. A partly plugged jet can fry a piston. Change fuel lines, keep them fresh.
If you get your hands on a good V4, forget modifying the thing and go boating instead. Use lots of throttle. My2cWorth