Frank-
You've got quite a Fish collection going there- I'd like to score an M3. One of the things you'll want to check is throttle shaft endplay- mine had about 5 thou, which caused the fuel pickup arm to stick. I had a machinist make 2 new bushings, and sleeve the linkage end of the throttle shaft with a stainless tube- he did a really good job on a tricky little project. He had at least 10 hrs into it, but only charged me for 8. However, now we have the process down, so if you need to know how it's done, let me know, and I'll email you. I also modified the high-speed adjusting screw to work like the later Fish- just remove a screw in the throttle shaft housing, advance the fuel pickup arm to full throttle, and run a setscrew in/out. We modified a standard 8/32 allen setscrew to take a deformable plastic plug in the side so it's self-locking and will not move under vibration- works quite well. Much better than removing the float bowl on the side of the road, along with a nonmagnetic brass screw to change 5 tiny, easily lost little .003/.010 shim washers! I've posted photos of the Fish teardown over on the Power Wagon Advertiser site (www.powerwagonadvertiser.com) under "Conversions & Modifications" - someday I'll try posting them here. With respect to your engine airflow requirements- what depression is the 390/420 cfm at? The "enrichment device" doesn't look factory to me- more like an owner's modification. The bronze arm looks like the original throttle lever arm for the carb- mine has one exactly like it. The tube appears to enter the float bowl above the fuel level, and end in the throttle shaft bushing- it doesn't make any sense to me. Is there a hole in the carb bore I'm not seeing? Have you removed the float bowl cover & divider plate to see if the other end actually penetrates the fuel arm cavity? The early Fish carbs had a slightly different arm that was relieved on the top to allow fuel to be pumped through a hole where the bowl vent tube later went. When the vent tube was added, two extra sets of holes were added to the throttle shaft (5 sets instead of 3). Maybe you have some one-off experimental factory version- that would be really rare!
