MikeC5

Interesting stuff Carl!

I said it was crude... I wouldn't try and calibrate it to height of pop... Putting thumb over hole will work too if you have a helper to crank.

You could try doing a crude compression test where you get a tapered rubber stopper to plug up the spark plug hole (with all other plugs removed) and hand crank. I would think any gross differences would be apparent in the relative force the cork gets popped out.

Advancing the spark in gasoline engines means the spark will happen in advance of the piston reaching TDC (top dead center) of the compression stroke on a 4 stroke engine. This improves engine performance in general (up to a point), depending on engine compression ratio, fuel quality, etc. Too much advance can cause engine damage via pre-ignition. Pretty much all gas engines up through the 20's did not have automatic spark advance which is why the lever is there. When starting the engine, particularly if using a crank, advanced spark timing is not wanted as it can result in a kickback of engine in opposite rotation to cranking direction; this can cause severe injury to arm/shoulder of person cranking. The lever allows the operator to manually decrease advance for starting. On the Dodge, the lever can be treated pretty much as an on-off switch since some of the advance taking place is done automatically via centrifugal weights in the distributor drive mechanism. When the lever is moved up the linkage actually rotates the distributor relative to the rotor inside which results in the spark being advanced by some number of degrees (of crankshaft rotation). Further advance occurs at higher engine rpm via the centrifugal weights. Automakers eventually got rid of the lever when vacuum advance was added (centrifugal advance still used also) and electric starters completely took over the starting duties. The other lever is basically just a fast idle adjustment which eventually became part of the more common manual choke mechanism for starting a cold engine.

I took an old spark plug, removed the insulator and welded on a pipe with threads to accept a modern compression gage adapter. I don't remember the actual thread sizes involved. You might be able to find one of the older compression gages that used a tapered rubber tip (a one size fits all).

Do you need to pre-mix the 1500 and grease?

Thank you Gents. Nice diagram CAH!

Does the coil case need to be grounded? I have my aftermarket coil sort of loosely sitting in the spot where the original once lived (with original top removed) and it seems to work O.K. It sounds like I should make an effort to properly ground it. I do plan to eventually get a proper repro.

It would depend on what I saw in the dumpster....

Good progress Gary. You'll get 'er going.

You have to remove the rear housing from the generator (which holds the rear bearing). Remove the brushes first by removing the 2 little screws holding the tab for each one. These screws also hold the tabs that go to field windings. You will need a short screw driver, a mirror and some patience to get to some of them. Then pull back the brush pusher arm (the spring loaded arm) and carefully pull brush out. Remove the rear bearing cover screws and bearing cover. Squirt some penetrating oil around the bearing OD to help it slide out of the housing in next step. Remove the screws holding the rear housing to the generator (my GA had 4). Some will require a long screw driver to get to (without removing carb). You may need to rap on the housing a bit with a plastic hammer to loosen it. Carefully pry on alternating sides and it should come off and leave the bearing in place (good time to check condition of bearing). Some careful maneuvering will get it by the carb. Remove the brush spring base plates by removing the bolts holding them to rear housing. You can now disassemble the arms/springs by removing the bolt that goes down through each spring (you may want to do this one at a time in case you forget how they go back together, take photos, etc.). Clean everything up good. Assemble arms with new brush springs. In can be a little tricky to get the spring to wrap around so you have proper spring force on the arm. Study the one you haven't disassembled yet carefully (ask how I know this). Re-install the brush spring base plates onto rear housing. Re-install cover on generator, install new brushes (optional) and re-install the brush connection screws. Make sure the field wire connection tabs are in place before tightening down these screws. I was able to do this without removing the generator but a mirror was needed on some and it took time/patience (your mileage may vary). It would be far easier to do if the generator is removed from the car. Your choice. Sorry I was too lazy to take photos but it would have been difficult with generator still in car.

That is a problem. If you can get someone brave enough to hold the brush down with finger pressure while you try the jumpers, it should work. Be careful...

Yes, just make sure your car is in fact connected with plus side of battery to ground. Over the years many were converted to negative ground (so I've read).

Did you try pulling back on the brush spring arm? The spring may still be working.

Try the jumper cables. It will bypass the foot switch, cables etc. and tell you if starter is the culprit or upstream.

Brushes basically allow electrical contact to be maintained between something spinning around to something stationary. In the case of a starter motor, the part that spins is called an armature. It has insulated copper wire wound around a shaped rotor with each end of the wire terminating at what is called a commutator. The commutators are spaced at equal intervals around the armature such that at any given time as the armature rotates the two brushes will be in contact with each end of one of the wire loop on the armature (there are several separate loops/commutators). The brushes carry current from the battery and energize the wire. A coiled wire with a current applied becomes an electromagnet. Remember opposites attract; like poles of magnet repel each other. In addition, there are coils of wire strategically placed and shaped in the generator case close to, but not touching the armature. When battery voltage is applied to these, a magnetic field is created (another electromagnet). The motor is designed so that the electromagnet created by the armature wire coils attact/repel the 'field' coil magnets with the result that the force makes the armature turn (since it is confined by bearings). As it turns, an adjacent pair of commutators make contact with the brushes and the process continues until the current is stopped. I'm sure there are some web sites with gee wiz graphics that may help explain but in a nutshell the brushes allow a rotating electromagnet to react to a stationary one.

Yup, those are the critters. The spring looks a bit mis-shapen but not necessarily broken. My guess is that whomever replaced them had some difficulty getting the spring to fit properly over the stepped spacer (on right side of spring in photo). You can pull back on the little tab that extends past the brush and feel the spring force. Compare this one to the other starter brush. If it feels noticeably weaker then the spring is a problem. Those springs look to clean to be very old (mine were quite rusty)...

I'm not sure what the conversion is for psi to inches HG... Automotive vacuum gages are usually in inches HG (in the U.S.).

I would open up the starter foot switch and take a look at the condition of the contacts first. If you suspect the contacts you can try starting it with a pair of jumper cables. If positive ground connect generator output directly to negative terminal on battery and the connect positive terminal to ground. If starter operates then you know the problem is 'upstream' (Cable condition, connections, starter switch). If it won't crank with jumpers then problem is in starter - check brushes, brush springs. I don't know why my text has a line through it....

With engine timing set properly, at idle, I believe you should get a steady reading between 17 and 21 inches HG.

Thanks Tom & Pete. I will try the IR thermometer on the connections. I'll check the grounding of the box too.

Are you sure the battery is sufficiently charged?

An update on my generator; I installed new brushes and brush springs, sanded the commutator, checked mica, cleaned things up, oiled the rear bearing (which seemed fine). Put it all back together and... it does the same thing. I'm not surprised really since the brushes and springs I replaced didn't really look that bad. I also sprung for a new battery. So it starts great. I did some more testing with a volt meter on the generator output terminal. After start from cold the output is up to around 16 V (idle) and over the next few minutes it drops down slowly to around 14. When I put the lights on it drops to around 13.5 V. After idling for 15 minutes or so, I blip the throttle a few times and it drops down to roughly 2 V. Turned off the lights and it stays at around 2 and slowly drops to about 1 V. I shut the car off, wait a minute or 2 and re-start. It's charging again to 14 V (no lights) and 13.5 with lights. Run for several minutes, blip throttle and same thing happens again. I was able to repeat the sequence again before quitting for the night. Pretty strange eh? The throttle blipping was to simulate driving. I'm starting to wonder if it isn't some armature mechanical issue that only happens at higher RPM. I guess I could let it idle for a half hour and see what happens. Any ideas? I should also mention that I have upgraded the starter box to use a large diode instead of the cut-out points.

Excellent description of what goes on in there.

Cold engine mixture enrichment is the slightly more technical phrase. The fuel/air ratio needs to be larger for cold starting. This can be done by adding more fuel and/or taking in less air for a given amount of fuel.... The Detroit Lubricator uses the former method. When you close the choke on a more conventional carb (with a choke butterfly valve) it decreases the air entering (and the higher vacuum condition in the carb pulls more fuel through the fuel jet. At least that's how I understand it.