Posted: Wed Jul 29, 2015 9:32 pm Post subject: Need engine advice
Hello, my jeep is a 1952 M38 but the engine is a chain drive L 134 from a 1943 Willys MB. The motor was rebuilt in 1979 but never run. I have removed everything from the motor to check things over and install fresh gaskets except for the crank and cam.
The motor had an MB front engine plate with a tab welded to it to accommodate the M38 motor mounts. I found an M38 front engine mounting plate that fits with no issues. My question is related to the rear engine mounting plate. I don't have one. The flywheel is the late 129 tooth M38 version. The bell housing is also the late M38 style. So my question is, which rear engine mounting plate do I need? Do I go with an MB plate or an M38 plate? Are there any issues I need to be aware of or will either one work?
The starter and generator are not military versions. They were six volt items that I had upgraded to 12 volt. They will be mounted like the original items were on an MB. Any advice or suggestions are appreciated.
Joined: Apr 23, 2008 Posts: 92 Location: Kansas City
Posted: Thu Jul 30, 2015 6:52 am Post subject:
I believe timing marks are going to be an issue. Timing marks on the MB/GPW are on the flywheel. Don't think there are timing marks on the M38 flywheel, nor is there a hole in the rear plate to view the timing marks if they were on the flywheel, those marks were on the crankshaft pulley and front timing gear cover. If you are running a chain drive cover there are no timing marks on it. I'm sure there are other issues. Those are the ones that jump out at me first. _________________ Bill
GP, GPA, GPW, M38, M38A1
Bantam T-3, M100
MVPA #1196
I will assume if you have a 129 tooth flywheel you have a large frame starter (mounts with two 5/8" bolts). The rear adapter plate must match the bell and starter. Using the late plate (5/8" dia starter bolt holes) will leave you with 6 unused 5/16" bolt holes (3 on each side) but will not be an issue.
Front plates vary so you will need to do more research on exactly which front plate with both ears forward you have. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
I believe timing marks are going to be an issue. Timing marks on the MB/GPW are on the flywheel. Don't think there are timing marks on the M38 flywheel, nor is there a hole in the rear plate to view the timing marks if they were on the flywheel, those marks were on the crankshaft pulley and front timing gear cover. If you are running a chain drive cover there are no timing marks on it. I'm sure there are other issues. Those are the ones that jump out at me first.
bbloom, I think you are correct. I'm not sure how I am going to tackle that issue but I am thinking about it.
Joined: Jun 15, 2014 Posts: 268 Location: Cambridge, Ontario, Canada
Posted: Thu Jul 30, 2015 8:01 pm Post subject:
I am in similar situation. Wes had just given me some good info last week. ...http://www.willysmjeeps.com/v2/modules.php?name=Forums&file=viewtopic&t=9046 _________________ 1952 M38 project
Brad
I will assume if you have a 129 tooth flywheel you have a large frame starter (mounts with two 5/8" bolts). The rear adapter plate must match the bell and starter. Using the late plate (5/8" dia starter bolt holes) will leave you with 6 unused 5/16" bolt holes (3 on each side) but will not be an issue.
Front plates vary so you will need to do more research on exactly which front plate with both ears forward you have.
Wes, I do have a large frame starter. It is an AC deco unit. Based on your input I'll be getting the late M38 rear mounting plate. The original front plate that came on the motor was an early Willys MB front plate that was modified by welding on a tab to accommodate the M38 motor mounts. The one I am using now is a standard M38 front plate. A trial fitting revealed no issues.
If your front timing chain cover has no timing marks or pointer and your crank pulley has no marks, notches or holes then you will have to locate TDC accurately with # 1 piston coming up on compression. Then mark the cover vs pulley. Then back the crank up 5 degrees and make a 5 deg BTDC mark. On the F-134 you can find TDC accurately with a dial indicator but with the L-134 the spark plug hole is over the valves, not the piston. So you must devise a wigler that will have the needed bends to go over to the piston yet still indicate visibly the piston movement.
No matter how you mechanically determine TDC keep in mind that there is a small flat spot of several degrees that allows the crank to turn without moving the piston up or down. So when using the home made wigler method you must slowly come up towards TDC with #1 on compression and carefully watch the wigler movement. The instant the wigler stops showing a rise make a temp mark on the pulley with a corresponding mark on the timing cover. Now continue rotating the crank in it's normal direction carefully observing the lack of wigler movement. The instant the wigler starts to move down stop and make a new mark on the pulley. Now back the crank pulley backwards and split the reference mark on the cover equally between the two marks on the pulley. This is the actual TDC. Now you can add a pointer or a permanent mark on the cover for TDC and a notch or hole in the pulley matching it for the pulley's timing mark. Now rotate the crack backwards 5 degrees and make you permanent mark on the cover for the 5 degrees BTDC adjacent to the pulley notch or hole. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Thanks Wes! That will solve my dilemma. I'll print that out and follow your instructions. It should be easy to determine TDC because the head is off which will allow me to watch the rise and fall of the piston.
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