I am converting a McCulloch engine 40003206 (21cc?) and want to put EI on it. I have been reading posts but cant really understand it fully. What all do i need to put EI on my engine? Thanks Joe.

www.ch-ignitions.com

Good chance you are over you head already if you asking these questions.

But you need to machine a prop hub /adapter to house magnet for EI, unless you have the ability to machine a hub and broach a key slot in the correct spot, you are barking up the wrong tree.

Not to mention these small Macs have about .8 hp at best, you are wasting you time with this one...

I have seen conversion engines run with the magnet taped to the prop. Not nice to look at, but they did run.
So here is what is needed:
Ignition with battery and power switch.
Hall sensor (part of ignition), mounted to crankcase in proper position over/near the magnet to spark at 28° before top dead center.
magnet on prop drive.
The more tools you have, the neater your job can be. Having said that, a good craftsman does not complain about his tools.

thanks for the responses. i have a lathe and made the prop hub for my homelite 25cc so i will give this a try. idk if ill even put it on a plane i just like tinkering.

Does that engine have roller, or ball main bearings??

AV8TOR

if you have room to do it, make a timing ring to go over the prop adapter to hold the magnet and clamp the sensor to the crankcase snout with a hose clamp, that's about the simplest, other option is to take a hole saw to the stock flywheel and put the magnet in that then move the sensor to where it needs to be

If its the small 22.5cc trimmer or blower engine known as Eager Beaver it has ball bearings, some are full suppport crank and some are cantilever type.
It would be interesting to see what size airplane prop it would spin, one of the boat guys here did one for a boat and compared to a 25 homelite it was way down on power.

The reason I mentioned it to him, is because I have a 21cc Eager Beaver Mac engine that has roller main bearings. At first I was going to "chuck it", but then I realized that was partly why the engine was so light. I am going to make up some bronze thrust washers, and give it a try. It will definitely need some agressive porting work to make any power. I will get back to it one of these days...

AV8TOR

Made a few calls,heres what I found

40003206 EAGER BEAVER III-SX 02/88 to 01/89

Crankshaft bearing in this model are roller bearings.


40003206 III-S 11/86 to 01/88

ball bearings on 11 level model

roller bearings on 12 and 13 models

my engine has roller bearings and it also did come off of a McCulloch Eager Beaver III-SX. Both ends of the crankshaft are supported by roller bearings and i'm seeing how much extra material can be removed from the engine when you convert it to EI. Is 2024-T3 aluminum ok for the prop hub? Also, could one of the XYZ electonic ignitions work on this engine?

6061 aluminum would be better if you have a choice

I converted some 32cc Macs and bought the CH ignition conversions. It was bolt on and fly deal. No bother out of the box with timing or anything.

2024 machines better, has higher tensile strength than 6061 and has better fatigue resistance, overall its a better choice than 6061 in this application.

As far as grades of aluminum go you may be limited as to what you have on hand. It will be OK which ever.