Power head swap is it doable?

[Ross72]

Here is the problem, I have a '63 75 hp speedifour manual shift with a good lower unit and a '66 85 hp electric shift johnson with a good power head. Is it possible to swap the 85 hp onto the 75 hp?

From what I have read they are the same block (cu in) just different carb set ups.

Also, The Speedifour has a magneto and the Johnson doesn't. So can I swap the mag from the 75 to the 85 or will it work as is?

Sorry for all the questions, just really like the style of the speedifour and would like to get it going. If this isn't possible, I'll just start looking for a parts motor.

 

[Joe Reeves]

Re: Power head swap is it doable?

Relying on memory, that powerhead transfer should work out fine for you. If you decide to keep the automotive ignition setup, DO NOT use your present ignition switch wiring setup though.

The magneto ignition switch simply shorts out the points via the two "M" switch terminals to kill the engine.

The automotive ignition switch eliminates battery voltage to the coil via the "A" switch terminal.

 

[Ross72]

Re: Power head swap is it doable?

Joe thanks for the tip on the ignition, I was unaware of that. I figured the powerhead swap would work, I picked up the donor for $25. Looks like I will have to wait until after the first off the year to start the swap, but I think I will be very happy with the end result.

One other question. Can I swap power heads as is, just changing the ignition? Also,will this give me the extra 10 ponies?

Thanx,
Ross

 

[Joe Reeves]

Re: Power head swap is it doable?

Right off the top of my head, I can't think of any problems you'll encounter, and yes, you'll have a little extra hp there.