Here is a real find!
I knew it was time to adjust my carb synch as well as adjusting the idle mixture on my 40 Dells. They had been popping some on deceleration and my usual 26-29 mpg average was going down to 23-24. And my idle had gotten a bit too high.
Sooo-I gathered all the directions I could find including the Dellorto and Weber Carb manuals by C.B. Performance, Aircooled.net , the Circo directions and results from few searches on random sites like The Samba and here. All were confusing. None were clear (that is, not clear enough for my pea brain). I assembled all the tools, tach, carb wrench set, and began to work. First thing was to warm the engine then check the carb draws with the snail. I opened the snail
from it's box for the first time since buying it and found some instructions from EMPI, the snail distributor and man, are they easy-peasy! Simple step one, then step two, then step three fron start to finish. Even I could follow the steps and the carb synch and idle adjustments went smoothly with sensational results.
Great idle, zero popping , actually backfiring ( more like a "blub blub blub") at any time, wonderful power and fine AFR according to my PLX Air-Fuel Ratio meter. I am a happy guy. I wanted to share these instructions and will attach them to this post.
My notes; I used a nice tach hooked to the coil and ground to have a convenient way to see what my idle adjustments were doing. Too easy! John at Aircooled says that for Dells, find the strongest idle then turn the screws out an additional 1/2 turn but I did 1/4 turn. (He also says that for Webers, turn the screws out another 1 full turn after finding the best and strongest idle.) I could have never done that by ear as some directions recommend. #3 took extra patience because it's real snug back in there. I used a mirror to locatethe screw but not to turn the screw. That was by feel as I watched the results on the tach.. Also on both carbs I had to remove the rain hats and air filters to see the adj screws The other thing I did different was to start by seating the screws carefully---just mildly seating them as they are delicate. I turned them all out 3 turns to begin turning them back in.
And don't get confused by which way is turning them in vs turning them out. (In is leaner until you cut the gas completely off and richer is by turning them out. In is to the right and out is to the left (lefty loosie, righty tighty--right?) And be mindful that the rotation will seem different on each carb because the carbs are facing each other, be mindful which way you should be turning each screw! Always to the right for in and to the left for out. I know this sounds very elementary but I am sharing what would have beeen helpful to me when I stared.
Other than that, just follow these EMPI instructions along with the notes and you will be golden.