If such a resistor was originally present in your radio, though, it is always good to have a little extra protection, so you may want to replace with the same type. You may also use a fuse. Select a fuse which is just large enough to not blow when the radio is turned on and off rapidly about 5 times after warming up.
Thomas
Thanks,
Ross
:I cannot find your model number on this site. If you radio is an AC-DC type (35W4 or 35Z5 or solid state rectifier), the resistor prior to the rectifier is a sort of fuse/cushion for the rectifier. It will burn out if the radio shorts. In many radios it is spec'd at 1/2 watt, and often discolors after use. It may need replacing. If you wish to retain the fuse characteristic of this resistor, replace with the same wattage, and expect it to discolor with time. If you eliminate the resistor or replace it with a higher wattage resistor, expect the cathode connection strip within the rectifier to blow if the power supply is shorted out. Some radios do not have this protective resistor, and normally AC-DC radios do not short out, especially if all condensers are fresh. The low voltages within such sets tend to be easier on components. Normally it is the AC type radio in which the electrolytics short.
:
:If such a resistor was originally present in your radio, though, it is always good to have a little extra protection, so you may want to replace with the same type. You may also use a fuse. Select a fuse which is just large enough to not blow when the radio is turned on and off rapidly about 5 times after warming up.
:
:Thomas
Of course your troubles are not limited to the problems listed above. There are more, but we'll start here.
Thomas
Bill VA
:Your rectifier sounds fine. Warble in audio may be due to failing condensers, either electrolytic or non-electrolytic. It may also be due to poor connections at the volume control, or due to components in the 1st audio section being too close to those in the output section. If a condenser or wire in the 1st section is not well shielded from the output, a squeel or warble will form (motorboating). Also, if the speaker wires are too close to the 1st audio section, squeeling or motorboating will occur.
:
:Of course your troubles are not limited to the problems listed above. There are more, but we'll start here.
:
:Thomas
I think that a re-cap would be a good idea.
Thomas
Bill VA
:I guess. Do you think that the selenium rectifier is failing? I have several radios with these that work fine. I had one that would arc over and smell really bad, so I replaced it. Generally, though, if they have infinity resistance in one direction, and good current passage in the other, then they are working fine.
:
:I think that a re-cap would be a good idea.
:
:Thomas
Also, regarding selenium rectifiers, I find that the painted ones tend to last longer than the bare metal ones. I had one go and it stunk like something nasty. Is selenium actually poisonous? I have a General Electric photometer from 1942 which uses a selenium photo cell. It still worked until I washed it. I wish I knew how it was constructed. I think I washed the silvering layer off of it, because it still smells like selenium. For now I'm going to use a modern silicon wafer, found at Radio Shack, which fits perfectly. All I need to do now is find someone with an accurate foot candle meter so that I can calibrate my meter with a resistor. The silicon wafer puts out a bit more juice than the selenium one.
Thomas
Neverheless, I recall a (fictional) movie or TV program where a wife poisioned her husband by scraping selenium off of old selenium rectifiers and somwhow getting it into his system (so to speak)... Hi Hon... Would you like some Silenium Tea? I also recall that an antique radio website (darn! I wish I could recall which one!) was used for some of the antique radio advice and "scenes/props" in the show.
regards,
Mark K.
::Yep. Liability is a funny thing when giving advice on fixing radios. The way I see it, though, is that I'm giving assistance. If people get into trouble, then they should read a book and find out for themselves. I generally don't give bad advice--at least nothing that manufacturers didn't do originally (like make the chassis hot), but I guess I could. I wouldn't worry about that, though, if I were you.
::
::Also, regarding selenium rectifiers, I find that the painted ones tend to last longer than the bare metal ones. I had one go and it stunk like something nasty. Is selenium actually poisonous? I have a General Electric photometer from 1942 which uses a selenium photo cell. It still worked until I washed it. I wish I knew how it was constructed. I think I washed the silvering layer off of it, because it still smells like selenium. For now I'm going to use a modern silicon wafer, found at Radio Shack, which fits perfectly. All I need to do now is find someone with an accurate foot candle meter so that I can calibrate my meter with a resistor. The silicon wafer puts out a bit more juice than the selenium one.
::
::Thomas
:Thomas, the resistor is a 150 ohm 2.5 watt. I sent Ross the schematic. His radio is a three power portable with 1R5, 1U5, 1U4, and 3V4. It's from 1957. He needs to recap and replace that selenium rectifier with a silicone. That's what I would do first.
:
:Bill VA
:
::Your rectifier sounds fine. Warble in audio may be due to failing condensers, either electrolytic or non-electrolytic. It may also be due to poor connections at the volume control, or due to components in the 1st audio section being too close to those in the output section. If a condenser or wire in the 1st section is not well shielded from the output, a squeel or warble will form (motorboating). Also, if the speaker wires are too close to the 1st audio section, squeeling or motorboating will occur.
::
::Of course your troubles are not limited to the problems listed above. There are more, but we'll start here.
::
::Thomas
You should replace them. I should conform too. With little playing of mine and always unpluging I just kinda expect them to go on and on. Mine aren't used in the house but reading again about them is a good reminder to change them out. For all I've done I used a 1N4007 and never used the additional resistor.
Bill VA
:Bill,
:Since most of what I am used to is silicone and have several radios with "selenium" rectifiers, should I replace these rectifiers or wait for them to fail?? Just curious......could easily replace these rectifiers but do they have a high failure rate?? I know NOTHING about selenium (didn't teach that in tech school in the 80's). Most of the units I have with these are from the 50's and like to keep original (if still working). There are either incased in flat metal OR in a can.
:Joe (the other cousin).
:
::Thomas, the resistor is a 150 ohm 2.5 watt. I sent Ross the schematic. His radio is a three power portable with 1R5, 1U5, 1U4, and 3V4. It's from 1957. He needs to recap and replace that selenium rectifier with a silicone. That's what I would do first.
::
::Bill VA
::
:::Your rectifier sounds fine. Warble in audio may be due to failing condensers, either electrolytic or non-electrolytic. It may also be due to poor connections at the volume control, or due to components in the 1st audio section being too close to those in the output section. If a condenser or wire in the 1st section is not well shielded from the output, a squeel or warble will form (motorboating). Also, if the speaker wires are too close to the 1st audio section, squeeling or motorboating will occur.
:::
:::Of course your troubles are not limited to the problems listed above. There are more, but we'll start here.
:::
:::Thomas
Dave
With my equipment I leave them in. As long as condensers are fresh, they aren't likely to short out anytime soon. I'm also one who doesn't rewire AC-DC sets and then polarize the plugs, though. I like to keep things original. I guess it's all up to you.
Thomas
Bill VA
:Bill,
:Since most of what I am used to is silicone and have several radios with "selenium" rectifiers, should I replace these rectifiers or wait for them to fail?? Just curious......could easily replace these rectifiers but do they have a high failure rate?? I know NOTHING about selenium (didn't teach that in tech school in the 80's). Most of the units I have with these are from the 50's and like to keep original (if still working). There are either incased in flat metal OR in a can.
:Joe (the other cousin).
:
::Thomas, the resistor is a 150 ohm 2.5 watt. I sent Ross the schematic. His radio is a three power portable with 1R5, 1U5, 1U4, and 3V4. It's from 1957. He needs to recap and replace that selenium rectifier with a silicone. That's what I would do first.
::
::Bill VA
::
:::Your rectifier sounds fine. Warble in audio may be due to failing condensers, either electrolytic or non-electrolytic. It may also be due to poor connections at the volume control, or due to components in the 1st audio section being too close to those in the output section. If a condenser or wire in the 1st section is not well shielded from the output, a squeel or warble will form (motorboating). Also, if the speaker wires are too close to the 1st audio section, squeeling or motorboating will occur.
:::
:::Of course your troubles are not limited to the problems listed above. There are more, but we'll start here.
:::
:::Thomas
:Hi Joe & Dave,
:Well there you have it. I figured someone would come in and defend the selenium rectifier. And Dave is a good one and very adamant about it. I don't remember when I first heard about replacing them, a long time back. I think it mainly started over the toxic thing. It is a foul smell but just about anything burning in electronic equipment is probably toxic to some degree. You can tell Joe I'm kinda a flip-flop person on it. I know you can read about anything you want to on the net vaild or not. I'm always telling my wife that. I probably should have directed you Joe to some of the opposing views. You can find more info on the Antique Radio site. Dave has good credentials. You can always do a research yourself and make you own decision.
:
:Bill VA
:
::Bill,
::Since most of what I am used to is silicone and have several radios with "selenium" rectifiers, should I replace these rectifiers or wait for them to fail?? Just curious......could easily replace these rectifiers but do they have a high failure rate?? I know NOTHING about selenium (didn't teach that in tech school in the 80's). Most of the units I have with these are from the 50's and like to keep original (if still working). There are either incased in flat metal OR in a can.
::Joe (the other cousin).
::
:::Thomas, the resistor is a 150 ohm 2.5 watt. I sent Ross the schematic. His radio is a three power portable with 1R5, 1U5, 1U4, and 3V4. It's from 1957. He needs to recap and replace that selenium rectifier with a silicone. That's what I would do first.
:::
:::Bill VA
:::
::::Your rectifier sounds fine. Warble in audio may be due to failing condensers, either electrolytic or non-electrolytic. It may also be due to poor connections at the volume control, or due to components in the 1st audio section being too close to those in the output section. If a condenser or wire in the 1st section is not well shielded from the output, a squeel or warble will form (motorboating). Also, if the speaker wires are too close to the 1st audio section, squeeling or motorboating will occur.
::::
::::Of course your troubles are not limited to the problems listed above. There are more, but we'll start here.
::::
::::Thomas
Well, I have some spare Rochester model B carburetors in the garage for my Chevrolet. I'm going to get one out this summer and reroute the main discharge passage so that it goes out to a small heater box (and then back into the carburetor) which has a coil of tubing fed with exhaust gasses. We'll see if superheating the fuel, so that it is a vapor, gets you any better mileage. The same thing happens in a Coleman stove, so who knows! Sounds like an idea! We can see whether this is all a scam or if I have the only 1951 Chevrolet (or car for that matter) in the world that gets over 60 MPG. If I get 40 MPG, though, I'm not going to complain. There was a time when 20 MPG was considered excellent. 20 MPG isn't enough for me with modern gas prices. With cold weather, the car only gets 16.
Thomas
Hey Ross, did you find your schematic??
Joe
Well Thomas, I will tell you not to believe the stuff you have heard and read on the subject of fantastic gas mileage, but then you probably won’t know whether to believe me or not. To put it bluntly, you cannot expect to get much more than 16 miles per gallon from your 1951 Chevrolet. It has mostly to do with energy, and there is simply not enough energy in a gallon of gas to move that much mass 200 miles down a level highway. Even a modern full sized car weighing considerably less can’t do much better than about 30 miles per gallon, and that’s with a double overhead cam fuel injected engine, which is a lot more efficient than a stock ’51 Chevy engine. Also, a modern vehicle has a good bit less air drag and mechanical friction at highway speeds, and this is an important factor too. There are other factors involved, but even without discussing them, you can bet your bottom dollar that there is no great conspiracy out there somewhere covering up the laws of physics.
The gimmicks for unheard of gas mileage have been around for many years. I have seen ads in magazines of the 1920’s that claimed 75 miles per gallon, and also read the same thing in later publications while I was growing up. The most popular one was an idle adjustment screw with a small hole drilled through the center. This was supposed to make your engine run on more air and less gas, or some such nonsense.
About heating the fuel prior to combustion. It is ok to heat the fuel once it gets past the venturi in the carburetor, but not before then. The heat riser in the manifold already does this, so I don’t know if you could improve it. Supposedly, the fuel air mixture is right at the point of combustion just prior to reaching the combustion chamber, and any more heat may pre ignite. I imagine there is a safety margin there, so maybe you could fudge some.
You would probably do better by cooling both the fuel and air before it reaches the carburetor, but the gain would not be very practical. The hot roders do this for more power, but if you don’t put your foot into it too much, you will get better fuel economy instead. Once this denser mixture gets pulled past the venturi, then it is heated and expanded as much as possible before reaching the combustion chamber. In other words, superheated fuel prior to the venturi is less fuel or a leaner mixture, which is not desirable. You can easily do the same thing by changing the size of the main jet. When all is said and done about the heat of fuel, a more practical gain in fuel economy would be to remove your spare tire and jack from the trunk.
Another way for better performance or fuel economy is better distribution. Multiple carburetors or fuel injection can do this, but that would not be practical in your case. I had a 1953 Chevrolet with dual carburetors that got a little better fuel mileage. That is, if I kept my foot out of them. They were mounted on an Edmonds aluminum manifold with a water jacket that used engine coolant for a heat riser. It was polished to a high luster, and I thought it was a beautiful piece of equipment. It also had two oil bath air cleaners that were smaller versions of the original. Painted gold. By the way, this setup was originally installed on my uncle’s ’51 Chevy.
Man, I’d love to hear a pair of steel packs from the split exhaust manifold of a 6 cylinder engine one more time before I die. Especially on a still night in a quiet town from a few blocks away. Not raising Cain, but the mellow sounds of just cruising the town. But then, I am a hopeless case when it comes to the sounds of yesteryear, and there are a lot of other unforgotten sounds that I will never hear again.
Regarding the engine, I have tried the dual intake set-up. There was no improvement, and the feeling of more power was an illusion simply because with two carburetors opening for a given throttle movement that would normally open one carburetor, more is let in sooner. This makes you feel as though there's more power because the throttle is more sensitive. Still, only so much can go through that engine, and only so much does. No power increase there. I'm back to a single carb, and am enjoying good acceleration from that cast iron oceanliner anchor.
Regarding the heat riser, great idea, but in order to vaporize the fuel extremely efficiently, you have to heat it beyond normal standards. The problem with this, as explained in the Chevrolet manual, is that you super heat the air, which super expands it. Not enough air gets into the engine, and so you lose power. It would be better to heat the air very little if at all. With the heat riser system, though, you must heat the air in order to heat the gas. A compromize is made, yielding somewhat better efficiency, but also a lack of power. Pre-heating the gas prior to discharge allows you to vaporize it without overheating the air. I do not recommend vaporizing the gas in a bowl or something like that. I am saying that it should be vaporized in the passage between the main metering jet and the discharge nozzle.
I have not tried this yet, and I do not believe that my car will ever get 200 m.p.g., much less anything over 30 m.p.g., if that is even possible. I do think, though, that it is a wonderful idea. Fuel injectors accomplish something like this. With fuel under pressure, you can atomize it so that it is at least in fine droplet form like from out of a spray bottle. Once it hits the hot intake manifold and the valves, it is much easier to convert to gas form. The problem with most carburetors is that they atomize the gas into a very coarse spray. This leaves a lot of work for the hot intake manifold to do. Another plus to fuel injection, of course, is computer control via oxygen sensors. It'd be great to improvise a system which would operate a varying valve on the main metering jet of the carburetor, which would allow fine tuning via computer. At this point, though, you might as well switch to fuel injection. Playing such games with a carburetor is a waste of time.
I'm going to try the gas heating idea, though, to see what I come up with. Take a look at your Coleman stove sometime. When you first turn it on, that spray is kind of what goes on in your carburetor (not really that coarse, because the main discharge nozzle has a rush of air flying past it). After the tube is heated by the flame, that is what would happen if you superheated the fuel. Notice how there's no spray anymore. There's an invisible gas. Perfect combustion occurs.
Thomas
This system was used in the 80's it was called a feedback system.
Low 20's is good mileage for your vehicle, I don't think there is any way to get it much better.
Dave
I think that if my car was a Honda, it'd easily get better mileage. Honda knows how to do just about anything. They could take a Rochester model B to the moon and back. I used to hate foreign cars just because everyone else told me to do so. They sure beat the 90,000 mile oil burners of the U.S.
Thomas
3,150 lbs does not sound unreasonable for the weight of your car. My memory tells me that is about right, but what surprises me is that the newer cars must be heavier than I was led to believe. I don’t keep track of that kind of thing anymore, so should not have made a comparison based on hearsay. Maybe it is even worse to make a comparison based on my memory.
If you have gotten as high as 22 m.p.g. with your car, then so much the better. I used 16 m.p.g. as an example in my post because that is what you said you were getting. I still doubt if you can improve on that very much by modifying the action of carburetor, but some people said that an airplane would never fly, and thankfully they were wrong.
I am also surprised that you did not get better results from your dual intake setup. Mine definitely did. I am not naive enough to be fooled by a throttle movement giving the illusion of more power any more than you are, and proved the performance difference in more ways than one. Actual street performance competing with the other wild kids before and after was naturally one of the ways. I wasn’t exactly what some people would consider a kid back then, but I still thought of myself as one, even when I was your age. At your age, I still didn’t know what I was going to be when I grew up.
You are right about only so much can go through an engine, and that does not change. What can change is how it is distributed through the engine. A single carburetor on most 6 cylinder engines supplies too much to #3 and #4 cylinders, and not enough to all the others simply because they are further away. Therefore, they cannot do an equal amount of work. Chrysler’s slant 6 did a better job. Not only were the longer ramps closer to the same length, but there was one for each cylinder.
As for gas mileage, mine did do a little better, and that is why I wound up with the setup in the first place. My uncle kept complaining about how much gas his 51 Chevy used because it had dual carbs. I knew he would not be any better off, but gladly offered to trade his system with mine. Sure enough, I had a smile on my face and he was disappointed afterwards, regarding fuel economy. He stuck with the trade though, and never mentioned the gas thing to me again.
Since then, I have owned two other cars with dual carburetors. One of them was a ’57 Thunderbird with a factory dual quad setup. Before I restored the car, I ran the setup on a ’56 T’Bird with overdrive. I drove it in numerous caravans of about 30 to 50 T’Birds and always got better gas mileage than any of the other club members. Even better than the ’55 models with the smaller 292 engine and overdrive. Some of these trips were long enough to require fuel stops, and we usually compared pump readings.
Hey man, be happy with your cast-iron boat anchor carb. They don’t give near the problem as a cabbage head carb on a T’Bird. The only thing worse than a cabbage head is two of them on the same engine.
The other car with a dual setup doesn’t count for fuel economy. I restored a ’57 Chevy ragtop to 100% outward appearance, but went wild with a hopped up 350 ’69 Corvette engine. I got lucky and found a 1957 dual quad setup and installed it. The engine didn’t perform quite as well as it could have, but it sure looked cool. The best I ever got out of that thing was 11 m.p.g.
I studied your explanation for the heat riser and its related hot air, loss of power, etc. and haven’t understood it yet, so I’ll ask a few questions. How can the amount of air become less after it passes the venturi of the carburetor? How can heating it after that be a compromise? Where else can every bit of it go except through the engine, so how could this be a loss of power? If the fuel is heated almost to the point of ignition while it is still in the valve chamber, would it not be a vapor? Since the manifold pressure is a partial vacuum, I’d think that a vapor could be formed at a lower temperature than that required for a Coleman stove at atmospheric pressure.
If I misunderstood you, and your explanation was about heated air and fuel before it gets to the venturi, then I understand most of the problems involved. According to what I have been taught, any amount of intentional heat at atmospheric pressure, be it air or fuel, is a compromise, and will reduce engine power. Where air only is involved, this can easily be demonstrated by the use of carburetor heat when it is applied to an aircraft engine to prevent or eliminate carburetor ice in the venturi. If the aircraft has a fixed pitch propeller, this added heat can reduce engine speed by a few hundred revolutions. As for what happens when fuel is heated in the passage between the main jet and nozzle, I’ll have to give that some more thought.
Although fuel injection has several advantages including some that you mentioned, the main advantage for it is the same as multiple carburetors, only better. Fuel injectors can precisely measure the correct amount of fuel required for each cylinder, thus allowing them all to do an equal amount of work. In other words, stronger cylinders are not having to drag along weaker ones. Almost all of my experience with injection has been aircraft related, both piston and gas turbine engines, so I can’t say much about cars, other than owning a few. The injectors that I am familiar with are installed in a hot environment, so the fuel is fairly hot before it leaves the orifice. Maybe even what you would call super heated, becoming more or less a vapor immediately after exit. An actual spray is cool by comparison, and should not be allowed to hit a hot intake valve. I doubt if anything less than a vapor would hurt much in a piston engine right away, but any raw fuel in the form of a spray or a streamer will soon burn through the thin combustion can in a turbine. Scheduled inspections are required to prevent this kind of thing from happening.
I just gave some more thought about heating fuel in the passage between the main jet and the nozzle, but this causes me to ask a question. Your statement was, “I am saying that it should be vaporized in the passage between the main metering jet and the discharge nozzle.” My question is how can the fuel become a vapor while it is in this passage? Put another way, what separates the fuel molecules so they can become a vapor?
But then, I can easily understand how it can immediately become a vapor upon entering an atmosphere, especially in the venturi. I believe this should work better than a Coleman stove for at least a couple of reasons. One of them has already been mentioned. Another is that an external pressure is not required to get it there.
Now that the vaporized fuel is in the venturi, I’ll have to think out loud here for a bit. I was born and raised around things that used a modified version of the Lindsay Light invention. This included lamps, lanterns, clothes irons, cook stoves, room heaters, or anything else that used fuel regeneration for light or heat. Never had much use for a Coleman camp stove, but restored one for my dad about 35 or 40 years ago. Of all the ones I am thinking about, every one of them made use of the process right there on the spot, not somewhere else down the line.
Since your experiment does not burn the fuel at this point, conditions will be different. So let’s see. You have converted a liquid to a vapor using heat, then rapidly cooled it in almost a freezing environment. Seems to me that should be a perfect condition for super distillation. If so, how long would it take before the particles began to drop out? Would the additives drop out before or after the gas? Would the drop out be an appreciable amount before it reached the heat riser? I don’t know. Would the hot fuel vapor be enough to reduce the air flow in the venturi? It would seem so to me, but who am I to say? Would the increase in distance from the main jet to the nozzle have enough added resistance to lean the mixture? I don’t know that either, so maybe I should quit thinking out loud and go back to working on radio stuff. I thought I was going to finish my current radio project before a contest coming up right after the first of February, but have just about given up on that thought.
Regarding superheating the air, you must conceptualize this in your mind. The air coming in is heated and is expanded. This doesn't force anything out or change vacuum or anything. All that happens is that since the air is expanding on the way in, less is drawn in through the carburetor. It is a continuous occurance, not something that happens in cycles or something. It's kind of late now, so it's hard for me to explain. It's kind of like when you try to think about infinity or something. Your brain can't do that easily. At any rate, super heating the air doesn't change the pressure inside of the manifold or anything. I wish I could explain this better. Maybe I can to-morrow. I really should start a 1951 Chevy forum or something, because this is bad that I'm talking about it on here.
Regarding dual carbs, perhaps the reason why my carbs didn't improve anything was because I wasn't using dual exhausts. I guess the acceleration improved a bit. I guess I gained about 10 h.p. It was impressive. It just wasn't much, and gas mileage was the same. Furthermore, the instructions said that I'd only nead 3/4 turn on each idle jet, but in fact all adjustments were the same. The engine wouldn't run on 3/4 turn. I figured that this was because the intake was now divided between two carburetors, and so would draw only half as much from each, making original adjustments acceptable.
Regarding a single carb on a 6, the middle and rear cylinders do draw more when the engine is cold due to the liquid fuel (unvaporized) wanting to go towards the middle (easy path) and rear (slanted that way). When my engine is warm, all plugs have equal color, and I assume that all get about the same fuel mixture. Again, this is a concept similar to the heat riser super heating thing. It's hard for me and most others to get. Initially the middle cylinders do receive a charge of fuel first, and probably get more than the others. Once the intake is filled with the fuel vapor/air mixture, though, all cylinders receive equal mixture amounts (fairly equal), since they must all draw from this same mixture. Due to resistance in the passages, the end cylinders probably do receive a slightly thinner charge, especially at high speeds. If resistance is low, though, they all do receive a fairly equal charge.
I'll think about that super heating thing for a while and see what I come up with. Regarding unequal distribution, I added a PCV valve to my engine because I was getting gravvel in the engine thorough the ventillator louvers in the valve cover. I found that with the dual intake, I could not put the PCV system through the central windshield wiper port. The center cylinders would run lean. I had to tap two ports, one under each carburetor. Then all was balanced.
Thomas
You are right by using the word resistance when discussing manifold distribution, and you are also right that there is not a whole lot of difference in it due to the length of the passage. However, the small differences you speak of are exactly why multiple carbs can increase the performance on a stock engine, even if it was not but about 10 hp on yours, which I don’t consider all that bad Unless something else is done to increase the engine revolutions a good bit more, a single carb can supply enough air and fuel, so where else would the increased performance come from except by a better distribution?
Perhaps there is more resistance due to speed inside the passage than some people would think. This comes about because the air is accelerated very rapidly between pulses, which occur every other revolution in the manifold. If an engine only has one cylinder, the pulses are fairly straight forward and they move roughly the speed of the piston on the down stroke. This is fast enough to be affected by the resistance of a longer passage. If these pulses could be smoothed out over the period of two revolutions somewhat like a condenser can do in a radio circuit, then the resistance would be less. (We’re talking electronics here guys, ok?)
With 6 cylinders, things get a little more complicated. Each port is doing its thing at a different time, and each one can mess up the movement of another. Sort of like signals being slightly out of phase in a radio circuit and nulling each other to some extent. This extra activity adds resistance, and dual carbs can help to break some of this stuff up a wee bit, in addition to shortening the effective length of the passage.
An air plenum with enough capacity can smooth these unequal pressures out considerably, and is used on a lot of high performance engines. A plenum does the same thing as a condenser in a radio circuit, which is the main reason why I am mentioning it on this forum.
The air flow can be smoothed out even more by using the same methods that are used in radio. Anything that is tuned to resonance, be it a radio or anything else, is in a state of it’s least resistance. If the intake and exhaust ports are on opposite sides of the cylinder head, then the complete air flow system can be tuned to resonate at a specific frequency. If the length of the intake pipes are cut to a resistance that corresponds with the capacity of the plenum for a specific rpm, then the primary side of the engine will be tuned to resonate at that frequency. When the exhaust stacks are cut and trimmed to a resistance that matches the same rpm, then the secondary will be aligned with the primary, and the complete system will be in resonance. When the engine begins to generate power, an air current will begin to move through the system and gain momentum as the rpm or frequency increases. When the rpm reaches resonance, the air will be moving at it’s least resistance through the entire system in one continuous column. The momentum of this column will be enough to do most of the work, and all the engine will have to do is get it started, then keep it maintained. Of course, this is not free energy any more that of a crystal radio, since it requires a broadcast station to keep the resonance maintained. Who says we are not discussing radio on this thread?
Getting gravel in the engine through the louvers in the valve cover? That’s a new one on me. Did you block the louvers and draft tube with the modification, or what? Since you changed the manifold pressure somewhat with a PCV valve, was it enough to change the idle jet adjustment? If so, was it enough to change those of the dual setup? Just curious about these things, since I never did them on that engine. On your dual setup, how did it handle the heat riser?
Now, I’ll say something more related to radio. Before I do though Thomas, I’ll say that I have rather enjoyed our discussions on various subjects, even though we don’t always see things eye to eye on some of them. So, out of appreciation, I’d like to do a little bit of something for you. If you will email your postal address to me, I will send you a handful of NOS brown Bakelite AC line plugs. Mind you, my hand is much smaller than most men, so there will only be about ten.
I bought a bunch of these things way back when, but was not able to find them in my junk for the past 10 years or so. They weren’t lost. Just temporarily misplaced. Anyhow, I found them in the attic a few days ago, so now have more than I will ever need.
Now for you other radio guys who have taken the time to read this thread. I can sell these things at a decent price almost anywhere, but before I do, would any of you be interested in some of them for a good bit less? I hope an offer like this does not go against the rules of this forum, because I am absolutely not trying to sell them here. Just trying to give some of you folks an opportunity if you can benefit from it.
I don’t know what would be considered fair, but how does something like 25 bucks sound for ten of them, postage included? Is that too much for this kind of offer? Let me know your opinion about it on this thread. I will not let any of them go until I find out if this is in poor taste or goes against the rules of this forum. If it does, then I apologize in advance for attempting such a thing.
I took a quick shot of a few of these plugs and they can be viewed at:
http://www.imswebs.com/br/plugs.jpg
As you can see, there is nothing fancy about them. The hole for the line cord is not quite round. More of an oval shape. Clean brass on most of them and no corrosion that I have seen yet. But then I am blind in one eye with a cataract on the other, so don’t see all that well anymore.
Oh, one more thing. I may be a bit slow responding to any opinions or whatever. My blood pressure drops so low at times that my vision is grayed out too much to see what I write, and at other times it swings so high that my head almost explodes, so I am spending a lot of time in the bed. Almost everything I write on this forum is in bits and pieces until it is done. Perhaps the radiation treatments have aggravated this situation to some degree. Some days I fell pretty good and can get more done, but I never know when that will be.
Now if I could just figure out how and why those line plugs got in the attic..............br
Regarding the engine, I was thinking about that resistance thing for a moment and realized that you can discuss it just like in radio terms. AMAZING! I soldered the louvers shut and put a radiator hose on the ventillator tube. On this I put a small air filter. Looks stupid, but it's hidden in the fender. The idle adjustments are standard even with the PCV valve. The idle throttle setting is less since air is coming in through the PCV valve. The idle mixture remains the same as long as I compensate one air opening for another.
I have the carburetor set a bit richer now, due to another problem which I only recently discovered. Originally I did not have to do this with the PCV set-up. Supposedly the PCV valve which I am using is correct for my engine, and other than the following problem, has always performed normally. It isn't sticking, either. My engine has been getting poor mileage for several months now, and the plugs have been white. Recently I couldn't even get it rich enough to keep it running. The final shift in performance was so sudden, and yet I could find no manifold leaks (or faulty windshield wiper motor), and compression is fine in all cylinders (some are about 5 p.s.i. low). Well, now all plugs are light brown except for #5. I don't think that the rear intake passage is leaking, or else #6 would be white, too (maybe not...who knows). At any rate, my original theory about perhaps the gas stations increasing the alcohol amount must be false. I have to remove the head and inspect everything. Compression is fairly normal, but I still want to look for burned valves, etc. I don't know what's going on here. It's ticking me off.
Anyway, we seem to see eye-to eye now on all of this. Understanding engines is almost worse than understanding radio. I know what you are talking about with not heating the air and fuel at all--this causes a denser mixture--more fuel and air--more power. We'll see how my vaporizing the fuel works if I get around to doing it. It'd be a thrill if it worked and got exceptional mileage (even 30 m.p.g. would be fine by me), though I have strong doubts. For now I just have to get that darn thing working correctly.
Good luck with your blood pressure. I feel bad about that. Modern medicine has come such a long way, and yet we have so much more to discover. I'm not sure if Paxil is an accomplishment or not. I worry for anyone who has to take it. Before I start too many non-radio related subjects perhaps I should stop while I'm good.
Thomas
Yeah, I threw that resistance and resonance stuff in there on my prior post because you were concerned about discussing engines and cars on a radio forum. Some of the same laws of physics that apply to electronics also apply to hydraulics or whatever, and that is why electron flow is often compared with water or air. I can just as easily compare the theory of flight with that of radio.
The problem you described with your engine sounds almost like one that happened on rare occasions with some of the older engines, not just Chevys. This would happen all of a sudden, and the engine would not idle. If it did, it was extremely rough and no amount of adjustments would correct it. Sometimes it would correct itself later on, but if it did, it was not likely to be a complete fix. However, I do not know if this occurrence caused poor gas mileage or if it changed the color of the plugs, so you may be having a completely different problem.
You may have heard of the old fix that we used to do, but if not, I will explain it to you, even though it may not be your problem. What we did was cross two spark plug wires and force the engine to flash back through the carburetor several times. Seems to me like I remember this was done best on #3 and #4 for a 6 cylinder engine. The air cleaner has to be removed, and the idle stop screw will probably have to be screwed in far enough to keep the engine running. A fairly rapid throttle opening followed by an immediate release will cause a flash on some attempts, but not all. The right amount of gas has to be in the intake for a flash, so it is a matter of timing and amount of throttle opening to get it happening with any regularity. A few flashes may be enough, but 6 or 8 would probably be better before finding out if it did any good after putting the ignition wires back in place.
I always did these movements by hand with the throttle linkage, but if the flash is too close for comfort, I suppose you could do it with the foot feed. I don’t know why you young whippersnappers call that thing an accelerator pedal. Back when I was still driving, most of it was at a steady speed, and I did not do much accelerating by comparison. For my way of thinking, a throttle is on the dashboard and a foot feed is on the floor.
But then, when it comes to speaking politically correct, an aerial is the thing in the air from the radio in a car, the radio in a house, or for that matter, the TV thing on top of a house. When the lead-in and ground wire or ground plane is added to the aerial, then it becomes a system called an antenna. Whew! Boy, I had a hard time linking cars and radios on this particular post so it could be accepted on a radio forum....br
I've had that sudden no-idle thing, though, on other occasions. It usually happens when I'm on my way to work. Then I pull the choke out and keep going. About 90% of the time it's been a piece of microscopic crap in the main metering jet. I don't know how it gets in there, but it has happened to me about 15 times. My air cleaner is oil bath, too, so it's pretty thorough.
I'm interested in those plugs. I'll go for it. E-mail me if you wish.
Thomas
Back when I was a kid living at home, I tore apart a carb on the front porch looking for the reason this happens. Didn’t find it, and it still did the same thing after installing it back on the engine. I went ahead and blasted it out and don’t remember having to do it again on that particular car. I never investigated it further and chalked it up as one of the great mysteries of life.
Yeah! Marvel Mystery oil is great stuff. Love the way it smells in the can and also in the smoke. Used to keep some in a squirt can for light duty lubrication because of the way it smells.
OK then, hardhead. If you won’t send me your mailing address by email, then I will send you an email to get it. I may even do it today if the notion strikes me. …br
P.S. If any of you radio guys are reading this, the email is about AC power plugs which are used on radios, thus making this post suitable on a radio forum.
Thomas
Thomas
Thomas
See, now...I got some electrical in there.
Thomas
Could also be pinging excessively, then, because I enrichened the carburetor just a touch (slightly larger metering jet) due to my lean cylinder issue. I guess that would explain things.....seeing as it pings a lot when I pull out the choke. Making the mixture richer by other means would probably do the same thing.
Maybe I should start a car forum on Yahoo Groups or something. That'd be appropriate.
Thomas
Anyway, it was hillarious when the oil flew out of the air cleaner. The car runs well. Still needs more work. These old engines need CONSTANT attention. Most modern people never change their spark plugs and would never think to pour tune-up oil down the air intake for freeing up the valves. Modern valves don't usually stick. Modern plugs don't usually foul up. Maybe occasionally someone puts fuel injector cleaner in the gas tank. Back in 1951, though, you had to disect and disassemble the car once a year just to keep it running. Amazing. I love my car, though...otherwise I wouldn't have driven it for 7 years now. Last year I even almost chopped my finger off in the crank shaft. Don't ask about that one. It's a strange story. The engine wasn't exactly running, but the whole thing was stupid, never-the-less. I'm not about going under cars anymore (though I still do due to necessity). My bold fearless attitude has subsided quite a bit.
I built something interesting a few years ago. I built a transistorized control for the ignition coil. Basically I took 3 PNP output transistors and wired them in parallel. The points controlled the base. No other components were used. I got a perfect spark always, and the points no longer pitted. Then I shorted the thing out accidently and blew the transistors. I never did get around to rebuilding it. Seems someone else came out with the exact same thing right around when I was born (1979), so I guess I'm not such an inventor after all. To-day they sell conversion kits for my distributor, which are completely breakerless (didn't want to say pointless). I get by with the points, though.
See, I mentioned transistors and stuff like that. That's forum related, right?
T.
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I already told you why you don’t like big sparks and explosions kid, but you are like all the others your age, and just don’t pay attention. You have been protected from the cradle and do not know what hot really is. That’s why I told you to use the foot feed. Geeze, no wonder ya’ll need instructions beginning with 10 pages of safety warnings printed in several different languages. 8^) I know how close to stand next to a flame without getting burned, but had to learn it the hard way.
Seriously though, I can’t really say if leaving the air cleaner on changes the way the fix works. I’ve never tried it that way, and do not know anyone else who has either. However, I can say that the pressure had to be considerably more in the venturi, whereas velocity may be what is needed. I think it would be best to try and pull something out of the carb and burn it instead of pushing it back in further. But then, us old folks don’t know what this world is all about, so maybe you should not pay any attention to my guesses.
Transistor conversion kits for ignition were available way before 1979, but may have been different than the kind you are talking about. I never installed a kit, so really don’t know. I didn’t believe their claims back then, but now that I know better, I would probably try one on an old car. Not because of point life, but because of spark plug life, which can be about 10 times longer.
I can say that I don't have seatbelts in my car, so that's kind of risky. I think that it's foolish, though. I'd rather have the belts, especially with the metal instrument panel. You'd think that someone out there would make seat belts which have styling like an old car. They make just about everything else for old cars. Why not have a streamlined chrome handle with a cream plastic insert or something....styling like the old cars of the 1930s and 1940s....I'd have to draw you what I mean. But no, all they sell are generic black belts which look like they're from the 1980s. You could even have a stylish shoulder belt clip for the door pillar. I guess if I wanted to trash my car and put in one of those ugly race steering wheels or digital gauges (yuck), the new belts wouldn't look so bad. It'd keep with the trashy theme.
Thomas