TOPIC: 1969 Evinrude 115hp ignition conversion?

I just bought a '69 Aerocraft with a '69 115hp Evinrude that needs a pulse pack I have seen on different forums that people have replaced the pulse pack with a MSD ignition box but I was going to attempt to use a 4 pin GM HEI module instead has anyone ever tried this before?

I just used the GM hei on my ezgo golf cart very generic hei used the stock exgo trigger coil works fine wound up useing a ford hei coil

This will be an interesting thread for me. I have a '73 Rude 135 with pulse pack that runs fine but am always interested in archiving info on replacements.
I did convert my '67 100hp Johnson from a gen1 CDI to conventional ign with help from Bruce on this site. The info is all here for what you want.

Charles,

Does the GM system require the use of points to switch the pulse pack, or is it using a sensor and a trigger wheel?

Also, for anyone considering a MSD type ignition, keep in mind that a 2 cycle engine of this kind does not use automatic timing adjustments like an automotive engine does. All timing is adjusted by the throttle setting only. Idle is maximum retard and full throttle is maximum advance as per the manufacturers specification.

It has a censer and trigger wheel and the advance is in the hei they used it on a lot of different motors you can buy the hei for about 20$ I used a ford coil. I have wounded if you could run just the carb to speed the motor with the advance done automatic?

All advance and retard on these type 2 cycles must be from the throttle control. The system is completely different than that of a 4 cycle engine, or a modern 2 cycle engine. The timing at idle is often as much as 20 degrees AFTER TDC (late) in order to make the engine operate at low speeds.

If you look at the throttle plate(s) in the carburetor you will see that they either have a hole(s) punched in them, and / or a notch cut out of the plate where it meets the throttle body. This means that the carbs can never be fully closed,no matter how far the idle stop screw is backed out.

This is done to lubricate the engine at low speeds, and consequently, why these old motors load up and waste tons of fuel at low speeds. Most people don't realize that the carb on these 2 cycle outboards doesen't even start to open for the first 1/4 travel of the speed control / throttle lever. All the low speed operation is ignition advance or retard. Usually When the throttle is set 1/3 or more the timing has been advanced to full and the carburetor(s)is opened up gradually to feed the needed fuel. At 3/4 throttle, most outboard carbs are at half throttle - the last 1/4 (or less) of the travel of the throttle quickly opens the plates to full. This is to give a top boost for holeshot, but backs the carbs off for cruise. It is VERY different than a car or motorcycle.

If you use an automatic timing feature, the engine will not be controllable.

I wounder if that is a hold over from the days of pore 2 cycle oil.
I have always ran my motors at 50to1 or less but the golf car people run them at 128to1 and they really get hot. I run mine at 60to1.

Listen to Bruce, he knows what he's talking about. That's sorta why when you open up you carbs full throttle there really isn't much of a increase in speed from a comfortable sounding cruise.

Charles, I should also say that the constant induction of fresh fuel into the engine also cools the bearings and piston. Think of how little oil there is in one gallon or liter of gasoline. It's a miracle to me that any lubrication is possible from this at all! The internal parts of the engine only have that tiny percentage of oil in the fuel to keep them from burning up.


If the engine kept the fuel charge on the top side of the piston, like a 4 cycle engine or other modern 2 cycle, (with a separate oiling system) then the lubrication / cooling aspect wouldn't be an issue. But in these old guys, the fuel is being pumped through the entire engine and it serves 3 purposes, lubrication, cooling, and power.

If you have a motor to try with one of these systems, it might be fun to see what happens. But please do it with an engine that is disposable, because it could be damaged by the experiment.

50:1 is a good ratio for most outboard motors that have hard bearings. Marine motors work far harder than motors in land vehicles. An analogy of the job a boat motor does compared to a golf cart - If you can imagine a fully loaded a golf cart that is always on a steep hill - never any flat ground - never a downhill - always a steep hill - It's not an easy job.

I agree with you a boat motor runs under load all the time. I like to run my old 650 merk a about 40 to 1. I grew up on commercial fishing boats my dad ran a 210hp 318 for 10 years with out touching the bottom end and 3 valve jobs. It would be interesting to try the system on a motor that is expendable. Still don't know how the golf carts get by with 128 to 1 they are air cooled and run hot. It is a piston port motor also with read valves.