Ubetcha! Don't want to raise any hackles on the folks who swear by the Rochesters, but I consider the C/W's and H/W's to be a great upgrade. Simple to install, not that tough to get synchronized and once you've got them tuned you can just enjoy the drive.
One thing I found that makes the tuning a whole lot easier, are some "hats" that fit on top of the C/W's that allow you to use a uni-syn to get the carbs equalized. I made a pair out of scrap sheet metal, some duct tape and use a little dum-dum sealer around the base to insure an airtight fit. The Uni-syn seals to the flat top of the hat. I made two so I can just move the uni-syn back and forth while I adjust my linkage. I've checked them a couple times and they haven't needed any tweaking. The key is to get your linkage nice and tight and to be sure to snug down the lock nuts once you get them in sync.
The actual idle mixture was very close right out of the box...a minor tweak with the vacuum gauge and tach dialed them in. Once you get both your c/w electric chokes wired you'll eliminate your problem. I used the "hose in ear" old standby initially for synchronizing before I made my "hats" and didn't really have to make any major adjustments. Since we've be limited to the E10 blended fuel, I've had to richen my idle mixture a tad....noticed that I was popping when off-throttle and decelerating. Of course, fuel mileage has dropped off a bit. Some friends have had issues with "phase separation" or vapor lock in their water heated intakes after shutting down their engines for a short time. Adding a few clothes pins to the fuel line, where it snakes around the front of the valve cover close to the thermostat housing, has eliminated this issue.
The fast-idle circuit cuts off in my exhaust heated intake in about 15-20 seconds....a water heated system will undoubtedly take longer. You can release the circuit early with a tap on the gas pedal before your electric chokes cut off.
The beauty of the Langdon setup is that you can fine tune them. As long as I'm getting 18 mpg I'm happy. Probably could do a little extra fine-tuning and squeeze another mile/gallon out but the truck runs so strong that I just want to be driving. I know I could improve on my mpg with a taller R&P to get me a little further into the upper regions of the torque band. Might add that if you are running a filter between the regulator and the carb, to add another pound of fuel pressure if your regulator has a numbered dial. Keep us posted on your progress.
Dave
