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MC engine in CJ2A/3A
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Joined: 16 Nov. 2016
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    Posted: 08 Dec. 2016 at 2:45am
Anyone using a MC engine in a CJ2A/3A?  If so what changes have to made?  I'm aware of the 24v system but just wondering what else other than the starter is going to be a problem, dist? anything internally in the engine? The charging system, (genny VR, etc.) will be replaced.  Thanks for any tips and experiences.
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Bruce W View Drop Down
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Points: 9651 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Bruce W Quote  Post ReplyReply Direct Link To This Post Posted: 08 Dec. 2016 at 3:19am
 Everything internal is the same. Everything external is interchangeable. You can use a CJ2-A starter as long as you use the correct flywheel/ringgear and the 2A bellhousing. If you wish to use the MC flywheel and bellhousing, use a CJ3A starter, maybe 3B/5, I'm not sure on that.  Generator & Voltage regulator from 2A will bolt right up. The biggest problem is the engine front mount plate - on the CJ2-A, both mount pads point rearward, on the MC, the left pad points forward.  Piece of cake!   BW
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Out of curiosity what is the s/n of your MC engine? Around MC74419 in Jan 1952 there was a change of the block to bellhousing mounting. The earlier had an identical block as the CJ2a with the open neck starter. Post 74419 the block had extra bolts on the bellhousing (10 instead of 4) the bellhousing was a closed (non vented) style and the starter went to a closed nose where there was no longer a bushing in the bellhousing.

So as mentioned just be sure you get the right bellhousing, starter and flywheel to mate with youe early style or late style block.

Early block casting numbers are confusing because the foundry did not immediately change from casting identification 4-bolt 640187 to the 10-bolt 804380.

Differences between CJ2A and MC engines were external. Different head and water pump with water bypass hose, dual fan belts, slightly different attachments on the M38 intake for venting, pressurizing and vacuum, different carb, different crossover tube, fuel pump electrical, etc. but everything can be changed or adapted.





Edited by Tom in RI - 11 Dec. 2016 at 12:53pm
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Originally posted by Tom in RI Tom in RI wrote:

Out of curiosity what is the s/n of your MC engine? Around MC74419 in Jan 1952 there was a change of the block to bellhousing mounting. The earlier had an identical block as the CJ2a with the open neck starter. Post 74419 the block had extra bolts on the bellhousing (10 instead of 4) the bellhousing was a closed (non vented) style and the starter went to a closed nose where there was no longer a bushing in the bellhousing.




 
That was a 102 unit M38 production run, my Jan 1952 M38 is #99 of that run, engine SN 74754. For what it's worth the engines as described above employ the 12-1/2" flywheel and 124T ring gear. 
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Tom in RI View Drop Down
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Points: 1126 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom in RI Quote  Post ReplyReply Direct Link To This Post Posted: 11 Dec. 2016 at 9:38pm
Mine is #11 of the 102 pilot run. But the original engine is MIA - replaced sometime before 1962 with an RMC block.   A holy grail would be to find a MC 744xx engine ....
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Points: 95 		Post Options Post Options   Thanks (0) Thanks(0)   Quote old stuff Quote  Post ReplyReply Direct Link To This Post Posted: 12 Dec. 2016 at 1:23am
Picked up the engine today.  SN is supposed to be 68749 but I'll have to check tomorrow.  TKS

EDIT:  Decided to check by flashlight, it is RMC68749.


Edited by old stuff - 12 Dec. 2016 at 1:54am
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