MH44 EFI Update

David G

Well-known Member
I am hoping to have the MH44 EFI back together by Christmas as it was. The governor threw a weight, it had an oil leak on rear of the pan, oil leaking down the valves and a head bolt leaking issue. I pulled the engine so I could work on it easily. I ended up putting perfect circle valve seals on the head, so that should take care of the oil down the valve issue. I am going to pull the head studs out of my spare block and ditch the ARP studs that I bought. I ended up with 2 spare governors when I got the spare engine/parts, so that is changed.

I have decided NOT to pursue port injection on this engine. I think it is just too hard to get the injection timing to balance on the siamese manifolds. This problem exists on any engine that shares an intake runner between cylinders (Siamese). Injection is best if it starts and finishes while the intake valve is closed, there is no way I can do that on siamese due to valve overlap. This would be easy if the engine had flow through heads where the intake is on one side and the exhaust is on the other. I think the JD 20 and 30 series would work fine with port injection due to each cylinder having its own intake runner.

I am planning to focus my efforts on an electronic governor and updated hydraulics.

The electronic governor plan would use an off the shelf throttle body from a GM auto. I would use an Arduino controller that looks at the RPM pulse coming out of the ECM, a throttle position sensor mounted on the steering column, and a servo output to run the throttle body. This would be a totally drive by wire system. I can set the ECM to limit RPM, so there is no chance of a runaway. I would like to make the governor autotune so it can react quickly without hunting.

I bought an upgraded hydraulic pump this summer. The pump needs an adapter plate to fit up to the MH flange, and to have a place for a thrust bearing to prevent thrust on the pump. I have 2 spare pumps, so I would bore one of the existing gears and install an adapter to fit the new shaft size. I do have a concern with the amount of force the cam gear and existing 3 point cylinder can handle, so I would put an adjustable relief on the discharge of the pump. The reserve tank is only 2 gallons, so I would like to see if I can fit a larger tank behind the grille where this one fit. I would like to use this tractor to rake and tedder. We got a lot bigger rake this year with small lift cylinders, so the existing hydraulics do not cut the mustard.
 
Was the oil leak at the rear of the pan, or was it a rear main seal? If it's due to a rear main seal, check the main bearings, if worn they'll ruin a seal quickly. I enjoy your posts, just can't remember if the engine was overhauled before you started on the electronics. Keep us posted.
 
"Injection is best if it starts and finishes while the intake valve is closed,"

David, I know you've been studying this, so what is the advantage here? Seems you would want the fuel to go in while the valve is open?

Thanks!
 
I had originally thought so, but it seems the warmth around the intake valve creates better vaporization.

Welcome for other comments, I am learning as I go.
 
That make sense. Got to thinking it could also be a timing thing. At higher speed need to get things started happening early to have them in place at the right time.
 
Good luck with the governor. If it can respond in the same category as a cruse control on a car, it will be wonderful. I agree on the injection, with divided in the head ports, timing would not be optimal. Jim
 
Jim,

I have beat my head on this one, it is just not worth it trying to get the siamese injection working
 
I'd put it back to stock. That's a continental engine isn't it ? Hard to beat them. Nothing better than a simple carb. and ignition system !
 

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