[JCAllison]

Originally Posted by rotorwrench

A lot of those electric pumps allow fuel to pass through when they are shut down. It just depends on what design of pump is used. That set up will work very well although somewhat complex.

Hey Mr. RW,
Don't know what could be eliminated to make it simpler without it not being able to function.

On your carb set up I'll add this info but if it's working it doesn't mean you should change anything. The secondaries don't really start to draw much of any fuel until the plates are opened far enough for the venturis to start their magic. The only idle circuitry is on the primary side and it only works when the throttle plates are open enough to allow a draw due to the low pressure there. With the secondaries open, it's allowing ambient air pressure to go through there causing a lean condition.

Have to say that the condition of the Idle is VERY responsive to the FAM Screw with which the Secondaries are opened/closed. The Idle is VERY consistent.

You have some sort of balance going on there but it's not the way it was designed to work.

YES. BUT it does work.

The secondary fuel circuit is all up in the secondary feed horn area in the venturi where the idle circuit is down near the primary plates when they are in the slightly open condition. The vacuum advance just has to be relaxed in a retarded position to get a start. That's why timing is set at idle with the vacuum can disconnected & line plugged.

The 3.14 has initial timing of 12 degrees BTDC. At 80 years old, my vision isn't what it used to be. So I did some custom work on the Damper to make it easier to see. This is what was done:

AND

The left side of the Blue Mark is 16 Degrees BTDC. Was going to use that as the Primary Timing, but it made starting HOT difficult, so dialed it back TWO Color Marks to 12 Degrees BTDC, and it is good to go.

This gives you the start condition. It takes a while with throttle plates near closed to get enough low pressure draw to get the advance diaphragm completely pulled tight.

Yes.

You also need the vacuum to draw the warm air for the automatic choke stove. Your problem with the choke stove may have been due to the high performance cast iron headers if that's what you have.

Well, there is an interesting anecdote about THAT... Though I was never told about it, apparently my Mother was in a Right Front End Fender Bender at some time before Ms. American came to live with me. In working on the old Gal's Brakes, I found the Left Front, and BOTH Rear Brake Back Plates were BLACK. The Right Front Brake was MAROON. Then when working on the Heater, I found that the Pleated Rubber Connector between the Air Inlet of the Heater, and where the Air comes in wasn't right. It had had a piece of Sheet Metal made into an oval Tube, and was sealed up with DumDum. Quite BOTCHED, to say the least. Then when rebuilding the Front Suspension, found that the Right Front PI Parts were marked as C3A, instead of C4A like the Left Front Parts. Also, it is apparent that the Right front Fender has been repaired, and the Outside Headlight Bezel doesn't fit as well as the Left Front Bezel. With all that said, there is one OTHER thing to note. The PLACE in the Passenger Side Cast Iron Shorty Header where the Choke Stove should fit, has a DELETE welded into it, but the Driver's Side is OPEN! This is an indication that the Right Front Fender Bender took out the Passenger Side Cast Iron Shorty Header, and so they got replaced with a pair of Headers for a Three Two Barrel Set! And when the old Gal came to live with me, it had an ELECTRIC CHOKE CAP, and not the Hot Air Choke setup. So the Hot Air Choke setup had nothing to do with the 4100's Choke difficulties.

I'm not sure how the warm air line connects up to that set up since I have no experience with them.

I had intended to attempt to put the Hot Air Choke setup back on the 4100. Bought the Choke Stove that goes into the Exhaust Header from Greg Donahue. It was a little more than $50.00. But then I found the DELETE welded into the Passenger Side Header and that scotched the deal. Nonetheless, the Stock Choke System on the 4100 was a Rube Goldberg Device. Talk about complex. One would have had to be a magician to make it work properly. Deep sixing it was the best thing to happen to the 4100.

Manual choke is damn sure more reliable in any case so I don't see a thing wrong with that.

It was a MIRACULOUS transformation.

My avatar is a photo of my Pop at the Celone Airfield near Foggia, Italy in late 1944. He was a copilot in the crew of that plane at the time.

It appears to be a B17.

My military time was US Army helicopter engine repairman but that was a long time after that photo was taken. I have a helicopter customer up on the south end of lake Conroe so that's getting closer to your neck of the woods.

Speaking of Helicopters, my Mother's kid brother (Christian Fink), was a dive bomber pilot on the USS Enterprise during WWII, and then later was a Chopper Pilot on the Admiral Byrd Antarctic Expedition. He was the 23rd Helicopter Pilot licensed by US Navy. See Here:
https://cdnc.ucr.edu/?a=d&d=CJ199910...-txIN--------1

It's hotter than hades here too.

Know what you mean. But YOU guys don't have the humidity that we have here in the Sam Houston National Forest. I go through five T-Shirts a day. They just get wringing wet from sweat, and it's so humid that it doesn't evaporate. The condition is called "clammy". Uncomfortable.

Anyway, thanks for the informative response. Hope you're having a GREAT Sunday. Take care.

JC