Gearing Up a 1961 40 HP Evinrude

[sharpsburg]

A friend and I assessed the speed of my 14' Crestliner Commodore and 1961 Evinrude Big Twin 40 HP the other day. I was less than satisfied to learn that the engine propels this craft at a measly 27 MPH (according to his GPS). Is there any gear combination or special gearcase (like the hi-speed Cornaire lower unit systems that were used in the 50's) that are out there for this model? If so can someone reply with an e-mail link or an address? The 1951 25 HP Big Twin tht I also own propels the same boat along at 20 MPH-I'm more than a little embarassed at the comparison! Does anyone have a similar boat/engine combination of a similar vintage with which to compare?<br /><br />Thanks in advance!

 

[steelespike]

Re: Gearing Up a 1961 40 HP Evinrude

RV,<br />I think both your motors should be faster.<br /> Unless your boat is loaded with junk or<br />has some sort of hull deformity.<br /> Carefully check weight distribution,motor trim and height.<br /> Virtical height alone can effect speed as much as 3 mph.<br />Shouldnt change gearing etc. without knowing<br /> engine rpm and prop size.<br /> Have you adjusted your high speed jet for highest speed?

 

[sharpsburg]

Re: Gearing Up a 1961 40 HP Evinrude

Thanks for the reply Steelespike. The transom height etc. is alright for the boat (the anti-cavitation plate is level with the bottom of the stern) and I've worked with the trim as well for optimum performance. The carb has a fixed high speed jet which eliminates adjustment (unless I find a new bowl which seems unessessary). The only junk that I have in the boat is it's operator (and I suppose a little weight loss wouldn't hurt)! I think a propeller with some more "bite" might help me quite a bit though. I haven't gotten too scientific about what I have for pitch etc. Even so...I'd love to do about 37 MPH with it. Too bad the early OMC outboards' horsepower were rated off the crank and not the prop!

 

[Lark40]

Re: Gearing Up a 1961 40 HP Evinrude

I have a 1959 Crestliner JetStreak 14' aluminum runabout with an Evinrude 40. Very similar to your boat. GPS speed is 27.5 mph at 4200 rpm.<br /><br />Engine powerhead was brand new two years ago. Running a 10 3/8 X 14" factory prop. <br /><br />If you can find one - there were 15", 16" and even 17" pitch 2-blade props made for racing by Michigan. These would be your best bet. Of course, you could pay a prop shop to modify a stock prop to higher pitch.<br /><br />So, that's about it - our engines can pull skiiers all day long - but they can't rev up like Mercurys can.

 

[sharpsburg]

Re: Gearing Up a 1961 40 HP Evinrude

It would be nice to find a huge Michigan prop for my '61 Rude, but it seems she is acting up one me. In an effort to avoid electrical probs. I just replaced the points and condensers, along with one new coil. The other day the 40 conked out on one cylinder- Now what I'm getting is one cylinder and the second joins in every now and then. I have a few ideas. 1) I have a worn flywheel key (I know...I'm cheap I gotta replace it) 2) spark plug wire(s) might be a replacement, 3)perhaps some problems with my cutout switch or the momentary contact switch on the engine to ground the coils-both of which are jerry rigged (electrical tape over connections etc. Any other ideas would be much appreciated. It'd be fun to race you Lark40, but I'm kinda dead in the water! (Smile)

 

[Lark40]

Re: Gearing Up a 1961 40 HP Evinrude

Did you use a "locator ring" tool when working with the coils? If not, the coils will hit the inside of the flywheel and damage the magnet.<br /><br />Spark wires are easy to replace. <br /><br />To test the cutout switch, just disconnect the wire going to the outer stud.<br /><br />If it makes you feel better, my engine bogs down at 4200 rpm, when I know it should go to at least 4500. Still haven't found the cause....

 

[sharpsburg]

Re: Gearing Up a 1961 40 HP Evinrude

Thanks for the thoughts Lark. I had the boat out tonight and I've narrowed my problems down to the fuel pump. The engine idles alright and works well at 1/4 and 1/2-3/4 throttle. When I shove the throttle lever wide open the engine progresses like normal and finally dies slowly after maintaining wot for a short time. I'm guessing something isn't right with that pump. Did I mention that I like the old pressurized systems better? Anyhow...I aligned the coils with the boss's on the plate and rotated the flywheel by hand to check if there were any "rubs." Before I left tonight for the river, I disconnected the cut-out completely. When that didn't alter much I got to thinking about the fuel. It's funny though, my engine doesn't lurch like it did when the problem first occurred. Perhaps the new points, condensers etc. fixed another problem. Thanks again for the help everyone!