1956 15HP Evinrude performance

[rjezuit]

I need some opinions on what shape its in /what performance I should expect from my 15HP Evinrude. It has 102# compression on one cylinder 100# on the other, new ignition top to bottom, good blue spark on both, correct plugs,rebuilt carb, water pump etc. It is on a 14' plywood composite boat, 1000" total load for the boat, motor fuel, gear and people. Starts on one pull, seems to run strong and smooth, but I can't get over around 11-12 MPH. I want to check RPM, but need to get a tach. Thanks, Rick

 

[wbeaton]

Re: 1956 15HP Evinrude performance

I get about 36 kmh or 23 mph on my 12.3' aluminum boat. Your compression seems fine.

 

[tashasdaddy]

Re: 1956 15HP Evinrude performance

i think your boat is heavy for it. i got around the same as Wayne. on a 600lb, boat and load. but was a very efficient hull.

 

[rjezuit]

Re: 1956 15HP Evinrude performance

What HP motor would you suggest? 20? 25? Or maybe a Doelfin or other hydrofoil? Thanks, Rick

 

[wbeaton]

Re: 1956 15HP Evinrude performance

Just got back from the lake.

33.6 kmh or 21 mph on a 1959 (Princecraft) 14' aluminum. Just me (200lbs) and a full 3 gal tank in the bow.

I too, think you are asking too much from that motor. I just re-read your post. I thought its max load rating was a 1000lbs not that the load was a 1000lbs. I'd step up to a 25 hp if the boat can take it. Do you know the the max hp?

 

[rjezuit]

Re: 1956 15HP Evinrude performance

It is a boat I built myself from plans, with some modifications. Weight wise I could hang a 20 or small 25. I see the Johnson 20's from the 50's and 60's look to be th same weight as the 15, 18 HP from that era. Ratings wise 25 is max. I will try this weekend witha smaller load, and maybe try a doelfin. I do not think I am getting on plane, and if the doelfin lets me do that, maybe it will make a difference. Rick

 

[wbeaton]

Re: 1956 15HP Evinrude performance

Johnson didn't make a 20 hp in the 1950's. The 60-70's 20 hp is basically the same as the 18 hp. I get 43 kmh or 26 mph with an 18 hp. I wouldn't add the fin since it will always be underpowered even when on plane. Try an 18 hp or (pre-1978) 25 hp.

Also try adjusting your setup a little more. Try raising/lowering your motor on the transom and try all the different trim settings.

Do you have any photos of this boat? I'd love to see it.

 

[rjezuit]

Re: 1956 15HP Evinrude performance

None under power, but a few standing still. I raised the motor 1 1/2" to get the cav plate even with the bottom, and will try again this weekend. It's been to windy to take out this week in the evening on Lake Erie, and the small lakes are 30-45 minutes away, plus the price of gas. Rick

 

[wbeaton]

Re: 1956 15HP Evinrude performance

Nice vessel. The motor certainly doesn't look too small for that boat. You might try adjusting the trim too. Looks to me like it could come out a bit.

I didn't realise how close you are to me. The weather has been rather unsettled lately. I watch the wind speed and direction and as soon as it hits something favourable I run down to the harbour and put the boat in. I've even commuted to the office with my boat in tow a few times in the last couple weeks. Of course, my office is also on the water so I get a good look before I head out.

 

[rjezuit]

Re: 1956 15HP Evinrude performance

I'm about 15 minutes from the lake, but being shallow it kick up pretty good and fast with a wind. We have had a lot of thunder storms moving through lately and I never know when the weathr will cooperate. Rick

 

[rjezuit]

Re: 1956 15HP Evinrude performance

I know that they changed the powerhead, and increased CID when they went from 15HP to 18HP, but what was changed to get the same displacement motor to go from 18HP to 20HP? Did they just rate it different (differents RPM or rating rules) or was there an actual change to the engine? Rick

 

[rjezuit]

Re: 1956 15HP Evinrude performance

Any Thought from the experts? Thanks, Rick