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Another Carburator Problem
Posted: Sun Feb 25, 2007 7:06 am
by steveh
I have gotten mm M-38 jeep running and it starts and runs very well, however, it will only run smoothly on about 1/4 to 1/2 choke. As I would expect it needs a bit more choke when the engine is cold and the amount of choke required is reduced when it gets hot, however, it never gets to the point of not needing to be choked.
Assuming that I have a vacuum leak, I have disconnected and plugged all of the vacume ports and that doesn't make any difference. \
Thanks for the help.
Steve H
m-38 52-61702
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Posted: Sun Feb 25, 2007 8:55 am
by oreo3156
make sure you have your float height set correctly.
Posted: Sun Feb 25, 2007 4:05 pm
by wesk
Needing the choke partially closed when the engine is hot to ensure a smooth idle means you are short fuel and long on air. Do the propane check for induction leaks first. If no induction (Vacuum) leaks then it looks like you're short on fuel. This could be a plugged idle circuit or a low float setting.
M38's need the proper carb base insulator gasket with the metal V device which improves low speed fuel atomization. I noticed the new kits from AJP and MWM only have the 1A65 thick base gasket (plain).
The insulator is WO# A923, ORD # 7372543
When this is installed (goes in Metal V down) do not use the thick 1A65 gasket but use the 121-137 thin gasket between the carb flange and the insulator.
Posted: Mon Feb 26, 2007 3:19 am
by usma41
Same thing with mine. I have found that this is very normal. We have a member that has about 40 different vehicles (14 which are jeeps) and he always pulls the choke out a bit on whichever one he's driving and we'er in Florida.
Posted: Mon Feb 26, 2007 6:18 am
by steveh
Wow. I would have never found the gasket problem. The gasket that came with the kit did not have the metal flange. I will get one. Thanks.
I am not familiar with the propane test. I am interested in trying it. Could give me some info on it or where I can find the info?
I really appreciate all of your help.
Steve H
M-38 52-61702
Posted: Mon Feb 26, 2007 7:52 am
by wesk
Using a pressurized flammable gas like propane or ether or even spray oil like WD40 you spray it while the engine is idling at areas known to be prone to vacuum leaks like the carb base area, the intake manifold, vacuum plumbing and etc. If you notice a sudden rise in engine RPM that indicates a vacuum leak in that area.
Be very careful with this procedure.