Looking for someone that can rebuild a distributor or replacement for my 1949 Plymouth. It's an IAP distributor. Iv installed three sets of points and it keeps burning them in only a few miles. Here's what Iv done so far to correct the problem. Iv replaced the Coil, Cap, Rotor, Wires and Sparkplugs, I sent out the generator and regulator to have and checked and adjusted. Iv checked the voltage coming both in and out of the coil and its 6 volts just like it should be. Each set of points I installed I installed the matching condenser. My last shot is to replace the entire distributor with the thought that maybe something is going to ground. Am I missing anything? Any suggestions?
If they make a Pertronix for 6v, that would fix it, I bet. It makes up for any wobble in the shaft, too. Does the shaft have any side play?
The condition of the distributor, worn bushing etc. will not cause the points to burn. What will is one or all of the following: Wrong capacitor. 2: Coil without a resistor built in. 3: No resistor in line with the power wire going to the coil. The coil and condenser are supposed to be a match with each other. On a '49 they've been switched around a bit I'll bet. The in-line resistor, (used with a coil that doesn't have a resistor built in) sends full voltage to the coil & points when starting cold and cuts it back as the resistor heats up prolonging point life. If your coil has a built in resistor it should say so somewhere on the coil body but I'm betting it doesn't have one.
If the points are getting contaminated, that could cause them to burn. For instance grease from the cam or even excessive blow-by getting past the distributor shaft.
get a coil for a '65 VW and your problems will be over.
It is 6 volt and has a built-in resistor.
You should not have 6 volts at the coil after the coil has had power to it for about 30 seconds. There is a ballast resistor in the circuit. It allows a full 6 volts to the coil for starting then as the element heats in the resistor, the voltage drops to a range of 2.5 to 3.5 volts so the points do not burn out. It is usually a small white porcelain bar mounted on the firewall but on your 49 it may be mounted on the bottom side of the wire router above the distributor or somewhere else in the line. You may also need a "resistor coil." If you have the service manual for the car it will tell you or any competent auto parts store can find the correct coil or resistor, whatever you need. If you bought a generic 6 volt coil and installed it you probably need a coil with an internal resistor. Chrysler products of this vintage were notorious for burning points and coils. It's a 20 minute, 20 dollar fix.
A lot of Chrysler products of this vintage are hard to start even with a good battery, new starter, good cables, etc. The resistor is almost always part of the problem. As it ages, it doesn't allow the full 6 volts to pass through for starting. Or if it doesn't drop the voltage it burns out the points and the coil and the new points don't last for more than a few starts. Many of the coils with internal resistors will over heat once the coil is in use for awhile and the engine will either die or run rough because the points are arcing instead of firing evenly. I bought a beautiful 50 Dodge Coronet coupe at an auction years ago because they could get it to run but it would die soon after and absolutely would not start until it cooled off. It had a new carb, fuel pump, hoses, points, etc., etc. but the old resistor coil. I bought it and put a new $20 coil on it and drove it 250 miles home without a miss.
Where would I find a Ballast Resistor for a 6 volt system? The coil I have on the car has a internal resistor but theres no way to know if it is working. it would be easy to install an external one. I guess I would just tie it in to the wire that goes between the distributor and the coil? Would the ballast resistor be the same for 12 volts or 6? I could order one for a 60's mopar.
Update> I just checked the coil again, With the points open I got 6 volts on the battery side of the coil. On the points side of the coil I got the very same 6 volts. I left the tester on for about a minuet and no change in voltage. So with last test I'm to assume that the resistor inside of the coil is at fault and a new coil will solve the problem. The car never came with an external resistor. If there is no difference in 12 or 6 volt as to the resistor would it make sense to install a external resistor or try my luck with another coil?. Now that said there's another question. The car is positive ground, I have the coil right now hooked up with the positive side of the coil going to battery and the negative side to the points. Should I swap it around and put the positive side to the points because of the positive ground of the car? Have I hook it up backwards. I don't remember looking at the old coil wiring when I took it off.
Aaron gave you an easy and likely inexpensive solution.
If it is positive ground you need to have the wire from the points connected to the positive terminal on the coil.
The only way to determine if the resistor is working is to check the voltage after it has been opening and closing the points, either while turning the engine over with the points opening and closing or after it has been running for awhile. The current has to flow through the resistor to make it work.
The correct coil for your car is an Autolite CR4001. Any parts store should be able to supply that coil or a direct interchange.
Here is a link to a wiring diagram for your car.
UPdate> with points open there is no current flow, hence no drop. You need to stick an ammeter between the coil (-) and the closed points or other ground. I think the cheapie Harbor Fright DVM has a 10A range. 10A will burn probably burn up the test leads if left in the circuit too long, so make sure they don't get too warm.
I switched the wires on the coil. This time when I checked it I did get a lower voltage on the points side but it still runs very rough. I may have cooked the new points already. I have a new set on the way so when they come in I will install and try it. I will keep everyone informed. I'm starting to feel like the guys Stan got his 1950 Mopar from, all these new parts and still not right. To date, New Carb,Fuel Pump,Points x3,Condenser x3, New plug wires, New Sparkplugs,New Rotor and Cap, New Master cylinder, Rebuilt wheel cylinders, New brake lines, and a extra set of keys. I try to not let mechanical things beat me but this is getting close. Stan, I may have a 49 Plymouth for sale soon!
Ther is no such thing as a 6 volt coil with built in resistor. External resistors are not used on 6 volt systems either.
I suspect you have a bad coil. One other thing to consider, you will burn out points quickly if the key is left on for any length of time with the engine not running. It's one of the things we don't have to think about in modern cars with electronic ignition.
Correct me if I'm (probably) wrong but if it's a positive ground wouldn't the coil be hooked up "backwards", that is the feed wire going to the neg. terminal on the coil and the pos on the coil going to the points?
I don't know where I got that from. Some thing out of the deep, dark past. Also: would leaving the points open and hooking a test lamp to the point terminal cause the resistor, if it's there, to heat up & drop the voltage?
I'll bet a little money on this one. EVERY Ford 6 volt tractor system uses a ballast resistor in the circuit to the coil to reduce it to 3.5 volts.
"The Original Equipment Mfg (OEM) 6 volt frontmount coil is designed from the get-go to work with 3.5 volts, ok?. Except there is NO 3.5 volt battery, ok? So you have to reduce what ever the battery voltage is, by an electronic trick called a resistor. This trick is governed by Ohms Law and Kerchoffs Law."
"This resistor is carefully chosen to operate with the coil and the battery so that the coil always gets its designed voltage of 3.5 volts. Whether that is the OEM 6 volt battery or the 12 volt conversion battery, that OEM 6 volt coil needs to see about 3.5 volts for long life and easy starting."
""In fact, Ford chose a very special resistor that automatically changes resistance with temperature, and it has a special name, "ballast resistor". The colder the resistor, the less resistance. The less the resistance, the more power is available for the coil to make hotter sparks."
Come on over Royce, I'll show you where the ballast resistor is on all 5 of my 6 volt Ford tractors and on my 1940 Dodge pickup.
Stan, I'm a little confused. Does the resistor go between the hot wire and the coil or between the coil and the points?
Delco 6-volt internal GM # 1115380
Delco 12-volt internal GM # 1115238
Delco 12-volt external GM# 1115202
Ford 6-volt external Ford # 8BA-12029
"Ford products had their own series of coil designs that did not interchange with any other vehicles from 1928-'48. Ford then began using a conventional 6-volt, externally resisted unit from 1949-'55 and then converted to a 12-volt, externally resisted unit from 1956 to '74."
Ford 12-volt external Ford #D0RY-12029A
Ford "blue top" internal for electronic ignition Ford # D5AZ-12029A
Chrysler 6-volt firewall-mounted Chrysler # 862576
Chrysler 6-volt internal Chrysler #1300667
Chrysler 12-volt external Chrysler #2495531
Chrysler "tan top" external for electronic ignition Chrysler # 4176009
These numbers are listed as a quick reference only. Original manufacturers will show as many as 10 different part numbers for the same coil.
Here's your OEM part number for the Chrysler internal resistanct 6 volt coil.
Chrysler 6-volt internal Chrysler #1300667
Back it with facts, not bull crap.
Will, it goes in the power feed line to the hot side of the coil.
Stan that's a new one on me - my 6 volt experience is with stuff like Model A Fords and Pierce Arrows and other 1930's equipment. I didn't realize there were such things on 6 volt systems. None of those cars had them.
Are you sure a 1949 Plymouth has an ignition ballast resistor? That's the question isn't it?
I guess the ultimate responsibility when working with anything electrical or electronic is to know what you are trying to achieve, then go about it armed with the knowledge of what works.
The OEM coil would have been an internal resistor 6 V coil. In today's world those coils are probably unavailable so most Chrysler products running 6 V will have a positive ground coil with an external resistor wired into the feed line.
Kerchoff's Law; haven't seen that mentioned in many, many years. Where's the Left Hand Rule, (or is it the Right Hand Rule?)
Kirchhoff's current law (KCL)
The current entering any junction is equal to the current leaving that junction. i2 + i3 = i1 + i4This law is also called Kirchhoff's first law, Kirchhoff's point rule, or Kirchhoff's junction rule (or nodal rule).
The principle of conservation of electric charge implies that:
At any node (junction) in an electrical circuit, the sum of currents flowing into that node is equal to the sum of currents flowing out of that node, or:
The algebraic sum of currents in a network of conductors meeting at a point is zero.
Recalling that current is a signed (positive or negative) quantity reflecting direction towards or away from a node, this principle can be stated as:
n is the total number of branches with currents flowing towards or away from the node.
This formula is valid for complex currents:
The law is based on the conservation of charge whereby the charge (measured in coulombs) is the product of the current (in amperes) and the time (in seconds).
Too bad the calculus doesn't show up here.
Good one, Stan.
Don't fret about the fluxions Ricks. It's Greek enough as it is.
Well, what Griffey said.
Top of pagePrevious messageNext messageBottom of page Link to this message By Aaron Griffey, Hayward Ca. on Monday, September 30, 2013 - 11:08 am:
get a coil for a '65 VW and your problems will be over.
It is 6 volt and has a built-in resistor.
I don't care what you put on it for a coil but Volkswagon coils are negative ground, not positive like Chrysler and yes, there is a difference. If there wasn't they would not make coils in negative and positive ground.
From a Volks site:
"Helpful Hints & Tips:
Coil wiring is occasionally reversed, double check your connections to ensure you do not short your ignition circuit. The POSITIVE terminal is #15, the NEGATIVE terminal is #1.
If you are using standard points the original wire from the main wiring harness is BLACK, this goes to the POSITIVE terminal. The GREEN wire from the condensor goes to the NEGATIVE side of the coil."
'32 through 48 Ford V8 cars and trucks had a resistor on the passenger's side of the firewall for the coil. Same for the Ford 6 of '41 through '48.
The model A and model B did NOT have an external resistor, only the V8 did. Model B was 4 cylinder.
$ cylinder '33 & 34 were called Model 40 with B engine. No external resistor. They must have had a resistor in the coil to keep from burning the points out.
The V8 cars were often run without the resistor to make it easier to start when cold.
The V8 cars continued on with that same resistor through the '48 model year.
I remember a guy in St. Paul had a '50 Dodge pickup that would burn points out in an hour's driving.
After I changed his coil it ran for years without that problem.
A simple rule on coil polarity:
Whatever ground your electrical system has, that terminal wire should go to the distributor.
So, for a negative ground system, the wire from the minus (-) terminal on the coil should go to the distributor.
I installed a new set of points and it did help but it still idols very rough. Starts very easy though.
In the early Corvair, and I suspect many other cars, the Ignition On wire from the switch to the coil was a calibrated length resistance wire that would drop the 12v to 6v with the points closed. It was bypassed by a normal copper wire when the switch was turned to the momentary Start position.