Bloo

Beware cheapo pressure regulators. There are some out there that do not do what they claim.

Someone mentioned the vacuum advance. Definitely check that. Also, though I can't say for sure without seeing it, the vacuum advance probably moves a plate inside the distributor while the distributor body is bolted stationary to the engine. If that is the case, there is a ground wire from the moving plate to the distributor case. It is made of some special wire meant to bend all the time when the vacuum advance moves without breaking. It is probably mixed strands of copper and spring steel. Make sure it is in there and not broken. A bad one causes the symptoms you describe, usually accompanied by popping in the exhaust. While you are in there, it would be a good idea to make sure the centrifugal advance mechanism is free. A drop of oil down the center of the shaft (under the rotor) can't hurt. Check your spark plug wires and coil wire with an ohmmeter. It can be hard to get a good connection on the spark plug end. If that is the case, use a non-resistor spark plug as an adapter. Touch the center terminal. End to end they should be a few ohms if copper, and maybe 2000-4000 ohms (2k-4k) if resistor type. The exact number doesn't matter much. On resistor wires the resistance is distributed evenly along the wire, so longer ones should be higher in resistance. That does matter. If you find an outlier, it is probably bad. Look inside your distributor cap with a bright light for cracks. There is a carbon button in the center that must touch the rotor. Make sure it does. In a 1948 car, the button is probably spring loaded. Another possibility is that the carbon button is crimped in, and in that case a piece of bendy spring steel on the rotor reaches up to touch it. Either way, make sure the carbon is going to touch in the center. If you found a problem with a bad (high resistance) coil wire or spark plug wire, or a problem with the carbon button, replace the rotor with a new one after you fix the problem. Inspect your ignition coil's tower under a bright light for a crack leading from the tower down to one of the small terminals. If/when using points (definitely a good idea until you get it sorted out), always try a new condenser.

Nothing should leak on a refrigeration system. Oil visibly coming out is a sure sign of a leak. "Topping up" is a backyard cure that eventually ends in disaster because nobody knows how much oil is still in the system. Non condensable gases (typically air) in a refrigeration system ruin performance. The air shouldn't get in as long as there is some refrigerant still in the system at all times. That is usually not the case with a leaky system, despite what the owner of the car probably thinks. If you leave a system connected to a vacuum pump for 4 hours (or whatever the shop manual says) before recharging, the system will get cold. If you leave the pump connected overnight, the system will get colder.

I am on the fence about this. I like electronic ignition but it is important to keep in mind that it's chief advantage is it's ability to remain stable over time, not "run better" despite what 50+ years of advertising copy says. There are some technical reasons I don't expect electronic ignition to work out well on a 6 volt car. I won't rehash all that again here, but I will say that anyone who really wants to do it should get the car running right first. Then try the electronic ignition. I agree with others. It is time to get back to basics, starting with a compression test.

Yes it is the spring that sets the pressure. To be clear, this is the coil spring behind the diaphragm, not any other spring like one you might see pushing on the arm. The laws of nature make the pressure what it is. "Pounds per Square Inch" in this case boils down to the area of the diaphragm in square inches, and the force the spring provides in pounds at it's installed height.

It sounds like too much to me.

That's #1.

I considered suggesting that. It is definitely what I would do if I absolutely had to have a 12v accessory, although I have not done it so I am not sure what the pitfalls would be. If I were doing it, I would use one of the smallest frame internally regulated ND alternators, from a Kubota tractor or a Geo Metro or similar, and a small compact battery, like a big motorcycle battery, a lawn tractor battery, or I would highly prefer something sealed, like an Odyssey. The 12v system could be negative ground and completely separate. There would be about 22v between a hot 6v wire and a hot 12v wire, but as long as you are aware of that it is no big deal. Contrast that with a typical 12v conversion, which might be easy and might be tough depending on the car. Going from positive to negative ground introduces more problems. Each accessory or gauge requires it's own solution. Radios can usually be converted, clocks vary, a heater might need a different motor adapted. Electric wipers might also. Some gauges might never work. A Chrysler M6 transmission will probably never work, but you won't run into that on a Packard. Anyone who converts inherits some or all of these issues, no matter what their reasons are for doing so. Most guys don't have the will to see it through and never finish it. They wind up hanging some cheap aftermarket gauges under the dash and leaving some other things broken. Some of the guys at the local cruise in seem fine with this, but I like everything to work as intended. I had a lot of converted cars pass through my service bay over the years and I have never seen one yet that had everything working. Unless there is some pitfall I have not thought of, a small separate system would sidestep all of that.

As far as I know, Permatex #1 will say Permatex #1 on the squeeze tube. It is a hardening shellac-based sealer similar to Indian Head, but it has a thicker paste-like consistency more like Permatex #2 instead of being a brush-on liquid.

Well that's news to me. I own a 1936 Pontiac and have been watching 1935 and 1936 Pontiacs for years and I have never seen even one with an oval tail light. You might be thinking of Chevrolet(?). 1935 and early 1936 Pontiacs all have the teardrop shaped light. Late 1936 Pontiacs have a round light, the lens and ring of which will interchange with 1936 Buick 40.

A soldered on terminal preferably, or at least one crimped very well, better if insulated or sealed somehow. The battery shops have heatshrink tubing with goo inside that can seal up the connection. The trouble with those ones in the picture is the clamp connection is subject to all the same corrosion that the terminal itself is, but the clamp to the wire typically never gets cleaned out when the terminal does. That's two points of failure instead of one. Worse, the corrosion develops around a bunch of little strands, and even if someone realizes it needs cleaning, it gets harder and harder to clean every time. After a while you just have to cut it off. The corrosion continues to wick up the wire, and it isn't too long before you can't cut off enough to fix it anymore. They are literally designed to fail. EDIT: Something like this would be a good choice:

This thread is about replacing a 6v battery with two 6volt batteries in parallel. Voltage does not add when the batteries are in parallel. The larger cables are still needed.

Gravity would make the pressure the same in both boxes. The smaller pipe has more resistance to flow, and it will take longer to get the same amount of water through it. If you raised the pressure in the box with the smaller pipe, so there was more "push" than just gravity, you could make it flow like the other one. These water pipe analogies fall apart pretty quick, but it is a start.

Think of voltage as pressure in a water pipe and current (Amps) as flow. To get more flow at a lower pressure, you need a bigger pipe. If the water in that pipe were feeding a water wheel grinding grain or something like that, to do the same amount of work you would need move the same amount of water up to the water wheel.

If I do this enough, maybe I can afford some more Evaporust.

I was trying Ed's method (running it full strength). The reason it wound up diluted was I only had distilled water with me and had to add it to get home.

While that is technically true, it is a bit misleading. If one compares a properly designed whole 6v system with a 6v battery to a properly designed whole 12v system with 12v battery, the 6v system will require twice the current (Amps) to do the same work. That is why the cables are always bigger on 6 volt cars, and why only a very few people get away with using cables that were intended for 12v systems on 6v cars without trouble. They are typically 4 gauge, and that is just too small for most 6 volt cars.

The biggest problem is that the pressure that develops inside from heat will blow a hole in your solder as you attempt to repair. Most floats have a tiny hole somewhere independent of the seams with a small dot of solder over it. Open that hole while you do your repair. Then, solder it back shut last. You will need to do something to reverse the flow of air while you solder that little hole shut. Dunking the opposite end of the float, the end away from the hole, in ice water as you are taking the soldering heat away might work. Electronic "freeze mist" might also work, but you would probably need a second person to spray it at the far side. You don't want to overdo the cooling and get the air flowing the other way. To test a repaired float, sink it in hot water and look for bubbles.

Ed: That was my plan but the trouble is it can't seem to get 10 miles without boiling over with Evaporust in it. It does fine on water or G-05 coolant. I'll probably try again after I change the water tube. That will mean taking the water pump off so I will have an opportunity to check the impeller clearance. I'll probably have questions about that when the time comes.

Do you mean this kind? They are a guarantee of constant trouble.

Some of you have probably heard of forum member @Grimy's trick of using a ladies stocking or pantyhose as a coolant filter to catch any particles of rust coming out of the block and head that would otherwise wind up clogging the radiator. It is the same thing a Gano filter does more or less, except the stocking catches smaller particles. @EmTee did this trick on his 1938 Buick and posted a picture of what he caught here. https://forums.aaca.org/topic/375456-weepy-stocking-filter/ I did this trick before taking off on my trip from Washington to Wisconsin in the 1936 Pontiac, and the other day I took it out. That represents almost 4700 miles, plus some driving around this spring. Here is what I caught. And, I don't believe my system is full of rust like a lot of them are. In my opinion this is definitely worth doing. The next thing was going to be @edinmass' trick of running evaporust as coolant for a while. Not because I think it is particularly full of rust (I don't), but after talking in a thread with @Rusty_OToole some time back, and a little checking with a temperature gun, I have become convinced my water tube is bad. The engine runs 185-190 degrees all the time, with or without a thermostat, and the gauge sender is at the very back of the engine. Rusty was talking about Chrysler water tubes as I recall, but Pontiac's "Gusher Cooling" is basically identical to a Chrysler water tube. I didn't dare do the evaporust thing last year before the trip because I figured if the tube is bad, removing rust is going to make it worse. It also might open up a hole in some inaccessible core plug. Anyhow I thought getting rid of the rust beforehand would make getting the water tube out an easier job. In case anyone does not know what the "water tube" I am talking about is, here is @1964carlito's picture from this thread about his 1939 Pontiac: No such constraints now, so I drained the system and rinsed it out with distilled water. Then I pulled the old sock out (first picture above) and put a new one in in and filled it the system up with evaporust. It really didn't like it. In fact, it boiled over and lost about a gallon the first time out. I topped it with distilled water. It pushed a little more out twice on the way back home, and by the time I got there I had 2 gallons of distilled water in the system. I don't know if diluted Evaporust does anything, but it did turn a little darker. Over the next few days I only drove it a few blocks to and from the store, and started it occasionally and let it get to 170 degrees or so before shutting it off. After about a week of that, there was an event I wanted to go to so I drained the evaporust and pulled the new sock out. It caught more crud. It is the one on the left. It didn't really come through in the pictures but the color of this trash is green. Additionally, there seemed to be an evenly deposited coating of dark olive green colored crud inside the head, maybe .030-.050" thick. You could easily wipe it off with a finger, it was watery and not solid at all. Weird. The antifreeze I have been using lately is yellow, not green. I refilled the system with distilled water and a new sock, and drove the car for a couple of days. It ran cool again. I drained it again and pulled the sock. It is the one on the right above. More crud. After running with distilled water the green crud was gone, but the dark green (when wet) color remains on the cast iron inside the head. I put in yet another sock, still in there, and refilled the system with G-05 coolant mixed 50-50 with distilled water. I drove it about 80 miles on a hot day yesterday to an event and back and it did fine. My main motivation for doing the evaporust now was that I thought it would potenitally make a rusted out water tube come out easier. I'll probably still do it, but after the water tube is changed.

All 1935 Pontiac, and early 1936 Pontiac. My 1937 Pontiac master parts book says: A second tail light was an extra cost option.

Yes. Since there is twice the capacity, it takes longer go dead, but also longer to charge. You're much less likely to run out of power. If for some reason you do run them down, just put the charger on when you get home. The car isn't going to take care of it on it's own in a reasonable amount of time. It depends. It would give you a truly awesome amount of cranking reserve. One Optima is electrically larger than a typical group 1 6v battery of the 20s-50s. Some forum members have done it. If by some chance the car is having trouble chugging down while cranking and not starting easily I would fix that first. It should have started fine on a battery available in the 20s. More battery capacity won't compensate for undersize cables, dragging starter, etc., at least not for very long.

I used smaller. I was having trouble getting cord that big through the spark plug hole, despite Fords having bigger spark plug holes.

Indian head is hard setting, but will need overnight to fully harden. I saw some for sale recently, no longer called indian head, but still the same stuff in a brown plastic bottle. It was labeled Permatex gasket shellac. The important thing to note is that the maker is PERMATEX. Beware similar looking brown bottles from other makers. They are usually not hard setting.