Setting carb and idle

lee12 · Post by **lee12** » Fri Dec 11, 2015 9:23 pm

I just started m38 rebuild. New carb and fuel pump, rebuilds. Start jeep and all seems well, but it idles great for about 30 seconds then goes through a lug down stage with coughing, then levels back out. What is that? No matter the mixture it does the same thing. Never dies just lugs down and sputters for about 5 to 10 sec then levels out and idles perfect, over and over.

oilleaker1 · Post by **oilleaker1** » Sat Dec 12, 2015 5:31 am

One of mine chugged like that. A test is to spray some carb clean into the cross over tube while running at the moment it chuggs. If it smooths out, It's starving for fuel. The slow speed circuit in the waterproof 637S carb has a long supply tube that drops into a round well when you put the top of the carb on. The tube has a small hole in the end, and two small holes in the side. One of my 2 small side holes had a brass shaving stuck in it. That's all it took to cause the chugg.

. John

scoutpilot · Post by **scoutpilot** » Sat Dec 12, 2015 6:55 am

It could also be that the carb was not thoroughly cleaned in the rebuild process. If the carb does this continually, that is what I would suspect. What is the idle RPM you have it set at?

lee12 · Post by **lee12** » Sat Dec 12, 2015 7:50 am

Set at 600 per manual. I'll try spraying the crossover today. Thanks for the advice.

lee12 · Post by **lee12** » Sun Dec 13, 2015 7:21 pm

Up and down idle fixed. But now the points have become corroded in just the short time that I've run it. Any thoughts? I plumbed the vent lines to it and made the special fitting on the vacuum at .04. Condensation?
Build up was greenish on the points. Scrapped off with file.

scoutpilot · Post by **scoutpilot** » Sun Dec 13, 2015 7:45 pm

Greenish is pure corrosion. Clean them if you can, reset and try again.