M37 revving problem !!!

[justinv]

Hi,

Have an M37 which to a cetain extent was working fine. My friend decided oto fiddle with the mixture screew and all went bust.

It still starts and runs but not very well, at low revs it works fine but when acc pedal is pressed more than half way through it starts revving up and down.
This is done on all gears

Any ideas ???

 

[DLJ]

Break his fingers !!

 

[jluv1185]

 

[justinv]

any ideas guys ? as I am going to burn this thing soon

 

[jluv1185]

I'd find out the original setting, put it back and start from scratch. Sorry dont know much about the m37.

 

[m376x6]

He may of broke a bit of sludge or other debris lose from inside the carb and it's now drifting around inside your carb or lodged in the jet opening. If you're careful you can take the cover off without breaking the gasket and look inside to make sure it is clean and remove any sediment and junk from inside the bowl. There are some suppliers who have both NOS and new gasket and rebuild sets for sale. NOS are a bit iffy as some of the parts may have turned brittle or shrank over the years. A little compressed air with all the fuel removed first from the carb can blow a lot of stuff that is lodged in the ports and jets free. If you're not comfortable with playing around with the carb a carb shop or someone who will do it for you will be the next step. See if you can find an exploded view of your carb somewhere on line and remove the carb completely and give a disassemble effort a try for yourself. At the worst you'll end up with a carb that has some problems and requires you to give it to someone who can fix it for you. Much like what you have now.

 

[rosco]

A fundamental setting can be had by screwing a vacuum guage into the intake manifold and using that screw to adjust it until you have maximum vacuum. There should be an 1/8th NPT plug on one side of the manifold that you can use. Some intake manifolds had extra ports for cold weather starting aids. Use a port closest to the carb. This will give you manifold pressure, and not venturi pressure, which is best for adjustment, but will be close. If other problems exist, as described above, your milage goes from bad to worse, but can be minimized with max vacuum setting.

Lee in Alaska

 

[Eric's hifim37]

If the truck is idling fine then you need to adjust the governor. If the gov is not set correctly your truck will surge like your pumping the throttle up & down while your trying to drive it. If that is the problem PM me and I'll give you my phone number and walk you through it.

Eric..