Joined: Jan 27, 2014 Posts: 151 Location: West Palm Beach FL area
Posted: Sun Aug 16, 2015 10:26 pm Post subject: Converting back to M38 sealed Bellhousing from CJ style...
A PO of my 1951 M38 swapped in a CJ style bellhousing and what appears to be a 6V MZ4137 starter (foot pedal style used on early CJ3A). It is attached to the block with a CJ style back plate with a timing port hole. The electrics were converted to 12 volt. I can't tell for sure what engine I have as it appears the s/n were shaved off when the engine was decked, but all the M38 accessories would indicate it was an M38 era engine ( dual belt pulleys, crossover tube with fording vent plumbing, Transfercase vent plumbing, etc).
I have found that the CJ style bell housing is broken and a critical lug is missing. Wanting to replace the broken CJ BH, I acquired a correct M38 waterproof bell housing and backing plate.
Now I have determined this is not a straight forward swap back to original, as the starter configuration is different for the waterproof bell housing. Not having a rare and expensive 24v starter, or 24 volts for that matter, is there a way to adapt or use another 12v or 6v Jeep starter with the M38 BH?
Any advice appreciated... I would like to make it as original as possible, but can't afford to make the jump backwards to all 24v electrics at this time.
Thanks, Jeff _________________ 1951 M38 restoration project - Flightline Jeep MC 23923 DoD 6-51
1954 M-100 Trailer USMC Dunbar Kapple s/n M-750759 DoD 1-54
1947 Willys CJ2A - Harvest Green
1954 Ford F-100 Parts chaser - blueprinted Y-Block
Southeast Florida
Your 51 M38 would have left Willys with the old unsealed CJ3A type bellhousing (two screw inspection plate, timing window & small frame starter hole). The sealed bellhousing is a 1952 thing.
The absolute, only way to ID from what chassis an engine came from is the serial number. Anyone can bolt on any accessory to any Willys engine. Without the serial number on your block you will never be able to establish what chassis Willys originally installed that engine in.
The early unsealed bellhousings were installed on the early engine blocks. The late sealed bellhousings went on the late reinforced rear flange blocks.
Early block uses unsealed early bellhousing
Late block uses the late sealed type bellhousing. Not the six additional 5/16" bolt holes (3 on each side)
You can easily install the late bell on the early block by omitting the six 5/16" bolts. But to install the early bell on the late block requires grinding material off the right rear flange to clear the timing window. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Joined: Jan 27, 2014 Posts: 151 Location: West Palm Beach FL area
Posted: Mon Aug 17, 2015 8:52 am Post subject:
Thanks Wes. I believe I have the early block, as the timing hole is usable. I will get down to the shop later today to compare against the photos.
Did the early ('51) M38 have the vent lines on the gas tank and transfer case, rather then a local breather, or is my t/c likely from a later M38?
My complete casting number on the block is:
CC
10-24 641087-L-W5 AN1-CR-N2
Does this narrow down what it came from?
Jeff _________________ 1951 M38 restoration project - Flightline Jeep MC 23923 DoD 6-51
1954 M-100 Trailer USMC Dunbar Kapple s/n M-750759 DoD 1-54
1947 Willys CJ2A - Harvest Green
1954 Ford F-100 Parts chaser - blueprinted Y-Block
Southeast Florida
Joined: Jan 27, 2014 Posts: 151 Location: West Palm Beach FL area
Posted: Mon Aug 17, 2015 8:55 am Post subject:
Is there a specific bell housing casting number or style I should look for to replace my broken unit on the '51 M38??
Thanks, Jeff _________________ 1951 M38 restoration project - Flightline Jeep MC 23923 DoD 6-51
1954 M-100 Trailer USMC Dunbar Kapple s/n M-750759 DoD 1-54
1947 Willys CJ2A - Harvest Green
1954 Ford F-100 Parts chaser - blueprinted Y-Block
Southeast Florida
Then use the M38 ORD 9 SNL G-740 parts manual in section:
Group 03, 0304 & 0305 sections have the majority of the needed info on vent system parts vs serial number of the jeep.
Group 0103 will answer the flywheel housing questions.
The engine manual TM 9-1804A only discusses the early vent system.
The casting number does not offer any help in pinning down what chassis the engine was installed in. That casting number was used in the CJ2A, CJ3A, M38, Willys trucks & Willys wagons. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Then both your M38 and your existing block came originally with the early unsealed bellhousing. Your attempt to upgrade to the late sealed bellhousing may get a bit expensive for you. Particularly in starter selection. Early bells use the small frame starters mounted with 3/8" dia bolts. Late bells use the large frame (closed nose) starter which mounts with 1/2" dia bolts. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Joined: Jan 27, 2014 Posts: 151 Location: West Palm Beach FL area
Posted: Mon Aug 17, 2015 9:53 pm Post subject:
Thanks for all the help, Wes.
I am going to stay with the '51 model year set-up, as that matches my data plates, and probably most of the other parts.
That's not to mention the savings on the Starter!
All the best,
Jeff _________________ 1951 M38 restoration project - Flightline Jeep MC 23923 DoD 6-51
1954 M-100 Trailer USMC Dunbar Kapple s/n M-750759 DoD 1-54
1947 Willys CJ2A - Harvest Green
1954 Ford F-100 Parts chaser - blueprinted Y-Block
Southeast Florida
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