RE: Norvel 074 vs Novel 061
The Norvel .074 idles and accelerates exceptionally well despite not having an adjustable airbleed. The .06, however, needs that feature. There were two versions of the .06 (and .049). The AME had three transfer ports and the Big Mig had five. The .074 has five ports as well and the .06 Big Mig with the five ports idles and throttles better than the AME's three port. But it's not perfect. However, if you maintain the same fuel, all the time, you CAN adjust the airbleed with a small three point file. All three engines have an air bleed SLOT that you can open up VERY SLIGHTLY with the file. A tiny bit at a time, you can't go back if you over do it. Well, you can but then it gets REALLY complicated.
Another method of getting a better idle is to adjust the compression. If you find your idle to be rich and if you don't want to start hacking at the throttle, try this. Adding copper gaskets/washers results in the need to close the main needle a bit. This serves to lean out the idle at the same time. Sometimes that's all it takes. But remember, if you change nitro content, you'll have to start all over again. Best fuel for these engines is 25% nitro for power and throttling.