It’s alive! Motor passed the test on the lake!

[nj-boatbuilder57]

I’ve posted a lot about this motor (35HP mashup ’57 Javelin / ’59 Sovereign), and I’ve got it running with all of the demons exorcised. That said, there’s only so much that can be determined in a bucket, so I figured it was time to put it in the lake.

I had planned this all week: "Saturday is lake day!" But Friday night the weatherman predicted a rainy, lousy weekend so we scrubbed the test. However, around noon on Saturday, it had stopped raining. The weather was gloomy & grey for sure, but no rain so we decided to go for it!

With my boat (about 900 pounds), everything ran great. Speed topped out at about 28 MPH with me & my buddy (each about 180 pounds). There were moments at certain speeds / RPMs that the motor seemed a bit "unhappy", but once speed picked up, the engine smoothed out nicely. I *think* it was due to a prop with too high pitch as it felt & sounded a bit like cavitation. My prop has no markings on it, but it came with the Javelin and looks to be stock. The Javelin parts book shows this to be OMC #376917 which I believe is a 10-1/2 x 13…..and I suspect that 13" is just too tall for getting this boat moving.

I’m going to buy a prop with a 11-1/2" or 12" pitch, and I suspect that will make things better, and much easier to get a skier up. Thoughts?

Anyway, we ran pretty much wide open for about an hour, and the engine seemed pretty happy to oblige. We didn’t take any pics….but promise to take some next time!

[davesko]

Glad you got it going! I’m sure it looks right at home on your boat. Enjoy it!

[nj-boatbuilder57]

Hey Dave…

I’m glad we made the trade!

There were a few moments over the past few months that I thought this day would never happen….but I’m pretty thrilled to be where I am right now!

[crosbyman]

if possible try to consider a tachometer to keep rpms in range with a low pitch prop for skiers…when not pulling skiers

Joining AOMCI has priviledges 🙂

[fleetwin]

Well, I would certainly try to confirm the pitch of the prop….If it is a 13" prop, that may indeed to "too much" for the engine, depending on you hull and load…

[nj-boatbuilder57]

I measured the prop (2 heights over distance, then calculate the arc as a % of the circle)…..13.263". Owing for any slop in my measuring technique, I’m pretty sure it’s a 10-3/8 x 13.

[fleetwin]

Well, I would certainly "try" a lower pitch prop…Hopefully someone has one you can try without spending money for a new one…

[garry-in-michigan]

The standard factory prop for the 25 horse RD-Big Twin was/is 10 3/8" by 12 1/2" – the 35 was 10 3/8′ by 13 1/4" and the 40 was 10 3/8" by 14". Michigan Wheel made a 10 1/2" by 11" for barges and deck boats. There was also a four bladed Michigan Wheel that was 10 1/2" by 10". . . 😎

[nj-boatbuilder57]

So 13-1/4 was stock? Looks like my manual measuring technique was pretty darn close!!

Michigan makes a 10-1/2 x 12….I think that’s what I’ll try.

[Author]

Posts