New Here! Idling problems.....Arrggh

[ihaveissues]

Just bought a '77 620 a few months ago, Generally in great shape, ran perfectly until yesterday! Normally , after the engine warms up, (been cold here in NM lately) I'll come to a stoplight and shift into neutral, the idle speed drops appropraitely, actually a little too low I always thought. but it never died, just a little "cammy" if you take my meaning... yesterday after running some errands, neutral was revving scarily fast. Made me nervous so I cut my day short. Ive adjusted the idle speed screw, the mix screw, nothing. It still idles really fast. Not sure how fast, as there is no tach. a friend suggested the accelerator cable needed to be lubed, so squirted some wd40 down the tube from both ends, no change. Any idea what might be going on? Thanks for any suggestions.

[pedrotheconejo]

I have a 1976 620 that my Father bought new and now it is mine.

I have experienced a wide variety of different problems with the carb.

Many of them have been with the linkages of not only the throttle but also the choke.

Throughly inspect the carb on the vehicle looking for broken and missing springs, malaligned springs, detached linkages, distorted linkages, etc.

I frequently find that the spring on the throttle cable cam is too weak, or detached, and needs to be replaced. This is not the spiral spring on the shaft. You need a real spring from the cable cam to the engine block. This will insure that that throttle gets pulled back.

Then remove the carb and inspect it again on a table and look again for the above things again.

One problem that I had recently was that a steel fulcrum shaft, that was pressed into the cast carb body, that was used as a pivot point for the linkege, had actually started comming loose from its attachment to the carb body.

This fulcrum shaft was changing position, not only its rotation but it was also actually beginning to come out of the carb body.

I fixed it by completly removing it. I ground a small groove around the end of the shaft that would be repressed into the carb body. Clean the hole it cam out of throughly. Drill a small 1/16" vent hole into the base of the hole that the shaft came out of. I then used JB Weld and put it into the hole, and repressed the shaft back into it.

(The small 1/16" drilled hole allowed the JB material to vent out properly thus allowing the shaft to be pressed into the hole. The groove that I ground around the shaft allowed it to be locked in better with the JB material. )

I hope this helps.

My 620 is now dead for a lack of king pin kits.

Roy

[ihaveissues]

Thanks for the advice Roy! Turns out there was a small piece of metal stuck down in the body of the carb... looks like it may have been a feeler gauge at one point. Glad it didn't fall all the way down! Good luck with the kingpin assembly...