Quote:
Originally Posted by KULTULZ
JC, when you have the time, did the choke kit manufacturer suggest setting the carb up this way?
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Hey Mr K,
No. In fact when they rebuilt the 4100, they (supposedly) tested it on a 390 FE, Test Engine, and (again supposedly) did a bunch of adjustments.
And the Screw that is in the threaded Nub on the Port Side of the Carburetor, that is adjusted to keep the Secondary Throttle Plates from sticking in the Secondary Venturis, was ground off flush with the Bottom of the Threaded Nub in which it is screwed.
Used a Craftsman RotoTool, and a small Cutting Wheel to put a small Screwdriver Slot in the Screw's under-end, and removed it so that an Air/Fuel Mixture Screw (with the Needle Point ground down flat) could be put up into the threaded Nub Hole.
That AFM Screw is able to be turned Righty Tighty to increase the opening of the Secondary Throttle Plates, or turned Lefty Loosey to decrease the opening of the Secondary Throttle Plates. And because they are opened to allow Air through them, the Throttle Plates NEVER go completely closed and so NEVER stick in the Venturi Bore.
Some years ago, it occurred to me that if there was a Screw in that threaded Nub Hole, that it would be possible to make the 3.14 idle on the Secondaries. So I have it a try, and sure enough it worked. Reported that on the FMF, and one of the guys there berated me for doing it saying it WOULDN'T work. I responded with it WOULD work, and in fact it was already being done.
It was some time later that Ross (remember Ross with the 429 Mustang?) was kind of mentoring me, and he just hinted at doing what I had already been doing with a temporary Bolt, which had to be turned with a Wrench.
But it wasn't until the 4100 was gotten back from Champion Carburetors that it was found that the AFM Screw was of the same size and thread as the Screw in the threaded Nub Hole. THAT made it possible to turn the Knurled AFM Screw with one's Fingers, while the Engine is running.
The MAIN thing about this is that since the 3.14 is starting and idling on the Secondaries, and the Primaries are COMPLETELY CLOSED, there is NO Vacuum Advance taking place in the Distributor. That makes the 3.14 start easier because it keeps the Initial Timing from advancing when cranking.
Also, since the Curb Idle Screw on the Primaries is Completely off the Adjusting Pad when the Accelerator is off, the Secondaries, which don't change maintains the Pre-Set Idle. One can come to a stop without any Vacuum, AND the Idle never changes.
Look at the LARGE JPG of the Manual Choke Setup. At the LEFT end of the Bolt that the Manual Choke Cam pushes, you can see (pretty clearly) the AFM Screw, and how it is up against the Secondary Throttle Plate Shaft Lever.
I don't think that whomever designed the 4100 intended for this to be done to it, but there it is!
Anyway, have already this morning cleaned and stripped one of Lorrie Van Haul's Door Latches. Am just taking a break before doing the other one.
Have a GREAT Sunday.
JC