620 Carb rebuild

The carb had been worked on before. The slots on one of the nozzles was really buggered up. I finally did get it out and think I can salvage it. They are a bit pricey ($28). The fuel inlet strainer was crushed. Don't know how that could have happend. I will have to get a new one of those ($25). There was no gasket under it either.

We'll see how it goes. Finally to the question. I will need to adjust the idle needles when I get it back together. You are supposed to set the engine speed to 600 rpm then adjust needles to max rpm one cylinder at a time. The tach on the tractor is not operational. I have been looking at a combination digital tach/timing light. I have wanted a timing light for a long time. One of these should work on JD two cylinders shouldn't it? My other idea was to attach something to the belt pulley then read it with an optical tach. I have one of those for use on my radio control airplanes.

They say to short the spark plug wires (one at a time) to run on one cylinder. Must you actually short it to the frame or is it ok to just pull it off the plug?

Thanks for your help. I will post back on the outcome (hopefully successful). I figure I can put it all in a box and send to Roberts if I fail. Just need to get it back together before a big snow hits, which can be anytime around here.

For RPM/idle mixture adjustments I like to stick a piece of wire welder wire in with my plug wires usually at the cap. Then I use a ground wire with clips on the end to short out one side then the other. I don't like the idea of spark flying around plus if it doesn't go to ground it's harder on the coil and maybe condenser, cap and rotor as it has to go somewhere.