Before you take it all apart again, it sounds like the idle fuel adjustment is too rich. Try turning the idle mixture screw in a little (leaner) to see if the loping condition improves. If you have a vacuum gauge, set the mixture screw to obtain the highest and most steady vacuum level. You might also raise the idle speed slightly. If the idle speed is much too slow, the fuel metering can get upset and the loping will start. You should get a pretty stable idle condition at 500 RPM or a little higher. Much slower will get you a poor idle condition, although I have seen the Chev 6-cyl engines go down to around 400 RPM, but they get unstable at that level.
If you adjust the idle speed, you may need to reset the mixture screw.
Harvester
Harvester
