Priming my oil pump

[ocwd]

Ken,

That's a nice looking Jeep. Looks like you put some hard work into it.

I checked the ring gear and bell housing that was bolted to my GPW engine. The ring gear is 129 teeth and the bell housing is the late style with the 6-bolt top cover. Are there any issues with running a late bell housing on the early style engine? I guess the obvious issue would be the mounting issue with an early vs. late starter. So, I have a late bell housing and fly wheel/ring gear and an early starter. If I found a late starter, would the combo of early RMC engine, late bell housing, and late fly wheel work? The starter that was mounted was a 12 volt civy job. Obveously that combo worked with civy equipment.

Dave

[Ryan_Miller]

It would depend on your crankshaft. If you have an RMC engine, chances are you should have the later style crank shaft.

[wesk]

Dave,
RMC engines were delivered several times during the many M38 production contracts. Some were the early (1st & 2nd series) 641087 casting, some were the late (3rd series) 641087 casting and some were the 804380 casting.

The first two castings have only the large 3/8" dia bolts holes in the bell and block ( four of them) and used a timing mark on the flywheel with a small window above the starter on the rear engine adapter plate.

The last two castings had the four 3/8" diameter mount bolt holes in the bell and block and additionally 3 extra 5/16" holes in the left and right rear engine flanges for a total of 10 holes in the rear of the block for attaching the bell and adapter plate.

Since the bell housing determined which starter you must use then it also dictates which flywheel ring gear you must use. So early bell gets small frame early starter which mounts with two 3/8" bolts and who's shaft is supported in a small bushing in the rear face of the bell and must be used with the 124 tooth flywheel for the early MBP4301UT 24 volt starter.

Note that this early combo also accepts the 97 tooth WWII and CJ2A ring gear and the WWII / CJ2A 6 volt MZ4113 and 12 volt Mz4124 starters.

The late bell gets the large frame closed nose starter MCZ4001UT which mounts with two 1/2" dia bolts and there is no bushing in the rear face of the bell. This starter uses the 129 tooth ring gear.

Yes you can use the early setup on a late block and the late setup on the early bl;ock. The limiting issues are:

1-you must use them as sets early starter, bell, ring gear
2-When using late engine with early bell the casting reinforcement on the right flange of the block covers part of the timing window and if you wish to continue to use the flywheel timing marks you will have to grind some material from the flange.
3-some early bells will not accept the larger diameter 129 tooth ring gear.

[ocwd]

Thanks Wes. Excellent description. Looks like I need to find a late style starter. I have:

early RMC engine
129 tooth flywheel/ring gear
late bell housing

Thank you everyone for the comments.

Dave