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IHC E4A Questions

Mike McKnight

Active member
Disassembled an E4A a couple of nights ago to clean up and try to get working again, and have a couple of questions about reassembly-

1) I see there is a timing mark on the big gear that turns off the rotor. Is there a timing mark on the rotor also to line up both gears and time them? I am assuming/hoping so, as I didn’t think to mark the two pieces before I took them apart! :bonk:

2) on the main driven shaft for the rotor, after I got it apart I noticed there are TWO keyways cut into the shaft where the impulse slides on-how do I know which is the correct one??? This one I also didn’t mark!!!:rant:

Forgive my ignorant questions, but this is the first one I have taken apart....I consider it part of the learning curve!

This is the earlier style E4A, with the manual trip on the impulse.



Mike, I have the factory repair manual. I’m away from home at moment. I just rebuilt one a few months back but I don’t remember how I timed it. I’m sure it’s in the manual. I will be home tomorrow night. If you don’t get an answer by then I will get the answer for you.


I haven't worked on an E4A in a year probably. I do not remember if the drive gear is punched. I want to say it is but my memory may be wrong. They put a couple of different point cams on those mags and the keyway to coupling placement is based off that if I'm remembering correctly. Basically the cam is at a different angle thus requiring the drive to be in a different position. If Turbo doesn't get you an answer from his manual, I'll try to find mine or look at an actual mag and respond.


Active member
At least you are gaining knowledge all the time with this project and once back together you will have a nice running engine.
Hind sight is a wonderful thing so a good habbit to get into is to use the camera on your phone and take way too many pics of what you are taking apart for reassembly purposes.
Years ago I rebuilt an engine in a David Brown Cropmaster. I don't know why I did maybe its a habbit but I walways put the engine on TDC before taking it apart. When I took the timing cover off I notice that the 2 timing marks did not align so I made 2 new ones a a referrence. Fortunately I did, as I found out later that the cam gear was replaced and although the correct size and number of teeth came off a diesel model engine and hence the different marks.
So now I always take a heap of pics regardless of what it is I am taking apart, even if I have done dozens of them.
Keep us informed of your progress.