M38/M38A1 carb kit

mike470 · Posted: Sat Apr 01, 2006 10:16 pm Post subject: M38/M38A1 carb kit

I need advice Embarassed

I flooded my M38A1 While starting it this morning,After getting it running I headed off to Ma's & Pa's for a visit 150 mile round trip, it backfired often around 45mph out the exhaust, above 50mph under load it did not backfire. I have a carb rebuild kit but it is marked M38 on the box, did they use the same carb? I know that the carb was not done when the engine was last overhauled 20000 miles ago. I have suspected the carb all winter but it started to good to mess with. it burned a tank of gold today so maybe I should lay it up and do the carb. ANY ADVICE WELCOME. Confused

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Getting Dirty with my 1953 m38a1 or my 1955 m37

Galen · Posted: Sun Apr 02, 2006 12:35 pm Post subject:

No, an M38 & M38A1 do not share the same carb, & the rebuild parts kits do not interchange. While I am definitely not an expert on the carbs, it sounds like a diaphragm on the A1 carb could be going bad, as they are want to do. Wes K can probably answer this one with his eyes close.
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Galen
1947 CJ2
1953 M38A1

wesk · Posted: Sun Apr 02, 2006 12:51 pm Post subject:

The old NOS kits and foreign manufacture kits are not good for todays rebuilds using todays fuels.

The only quality kit out there are the Carb Shop's and The kit that john at Midwest Mil and AJP sell. These contain modern rubeer materials that are compatible with the modern fuels. The kit that Midwest and AJP sell are $55.00 and apply to both carbs. This means they put all the parts fro both carbs in one kit. It does mean the carbs are a lot alike. They are very similar but the porting and barrel sizes are very different.

A carb that suddenly floods or suddenly runs too lean generally can be repaired by overhauliong it but I'd try a little troubleshooting first.

1-Check the two diaphrams by removing the two diaphram covers. If one or both have failed replace them. This can be done without removing the carb. So can an inspection of the float and it's valve be done without removing the carb. These sudden malfunctions can gemerally be corrected without a complete overhaul. If the problem dictates complete removal and disassembly then by all means get a quality kit and overhaul.

The directions for overhauling either carb are on the web site and the kits can be had at these sites:
http://www.midwestmil.com/
http://www.armyjeepparts.com/
http://www.thecarburetorshop.com/index.htm
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Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php

mike470 · Posted: Sun Apr 02, 2006 6:13 pm Post subject:

Thanks for the info I'll check the diaphrams tomorrow. Embarassed

I cleaned the kit box, it is marked M38AL NAPCO I got it from Niagara Military Parts. I have the phone # if any one wants.
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Getting Dirty with my 1953 m38a1 or my 1955 m37

wesk · Posted: Sun Apr 02, 2006 6:23 pm Post subject:

If the kit is 20 to 30 years old the rubber won't hold up to todays gas.
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Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php

mike470 · Posted: Mon Apr 03, 2006 12:32 am Post subject:

whitch liquid gold is best for an f head regular or high test. Should a person run a gas additive? Afriend of mine did the engine 15 years ago when he owned it so it should have compatible valves & seats. A recient compression test showed no issues Cool

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Getting Dirty with my 1953 m38a1 or my 1955 m37

wesk · Posted: Mon Apr 03, 2006 10:34 am Post subject:

You don't need anymore than 80/87 octane mogas. A little leaded fuel mixed in or some lead substitute would be a nice tough. You can buy leaded fuel at your local airport. Pick up 2 or 3 five gallon cans of 100 Low Lead (which has a lot of lead in it) and mix it in at say 2.5 gals 100LL with each full tank. The two improvements needed to deal with the hotter running unleaded gas today is the hardened valve seats and steelite exhaust valves. Also make sure all your rubber diaphrams in the carb and fuel pump are modern materials. With the 100LL added you can bump the timing up to about 8 BTDC.
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Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php

mike470 · Posted: Mon Apr 03, 2006 1:41 pm Post subject:

I'll have to mix a brew and try it out,might be just the edge needed. Thanks as the WAR dept. and I tip the scales close to 500lbs. and we want to run some trails this summer with the local jeep club. Cool

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Getting Dirty with my 1953 m38a1 or my 1955 m37

mike470 · Posted: Tue Apr 04, 2006 2:54 pm Post subject:

Still can't find an exploded view of the carb. I think that the throttle shaft may be a little loose in the housing. ARE there bushings in the housing? Idea

This may require a trip to Dads to use his machine tools.
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Getting Dirty with my 1953 m38a1 or my 1955 m37

wesk · Posted: Tue Apr 04, 2006 4:59 pm Post subject:

The Overhaul instructions are still on our M38 Yahoo Group mjeeps group.
http://autos.groups.yahoo.com/group/mjeeps/files/M38%20YS637S%20Carb%20Service/

The correct blowup for the YS950S M38A1 carb is in the A1's ORD 9 parts manual.
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Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php

mike470 · Posted: Wed Apr 05, 2006 3:30 am Post subject:

Just didn't look hard enough Embarassed

My better half tells me all the time. Thanks Wes this is the info I needed.
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Getting Dirty with my 1953 m38a1 or my 1955 m37

wesk · Posted: Wed Apr 05, 2006 1:06 pm Post subject:

I got the YS950S blowup and parts list up on the Yahoo group today.

http://autos.groups.yahoo.com/group/mjeeps/files/M38%20YS637S%20Carb%20Service/

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Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php

mike470 · Posted: Thu Apr 06, 2006 4:06 pm Post subject:

Thats great Wes. Really ups my comfort level to have a diagram. I got the M37 cranked up today almost ready for Provincal saftey inspection. Should soon bolt the top on and put the M37 out Razz

and the jeep in for a carb overhaul and lube inspection.
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Getting Dirty with my 1953 m38a1 or my 1955 m37


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