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Norman@two2cool
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Dec 24, 2008, 5:57 AM
Post #1 of 15
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51 Chrysler 6 cyl
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I have a 51 Chrysler with a 6 cyl. engine and a positive ground electrical system. It was starting fine untill I let it set for a few weeks. It has allways spinned over slow so I had the starter checked and one bushing was replaced. I replaced the cables and a new battery was installed. it spins slightly bettter now.
I replaced the points, condensor and wires. I also bought a new standard ignition coil 6v with an internal ballast resistor (it says no resistor needed).
My questions are:
1. since it has a positive ground what post on the coil +- do I hook up the wire coming from the ignition switch.
2. question one would answer this but which the wire from which post on the coil +- goes to the distributor.
3. Does anyone know the timing procedure for these engines?
4. can anyone tell me about the electrical box that is on top of the engine? It looks like it has a resistor on it and another device. It is also wires connections to two places on the carburator.
4. What would be considerd acceptable compression for this engine with all plugs removed.
any help willbe appreciated Norman
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Tom Greenleaf
Ultimate Carjunky
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Dec 24, 2008, 7:06 AM
Post #2 of 15
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Re: 51 Chrysler 6 cyl
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Just some notes on 6V pos ground systems as I own one and fortune would have it that it has needed almost nothing in the 41+ years I've owned it - original 61 YO coil and all!
Just checked mine as it caused me to wonder all over again. Wire to dist. show "pos" with test light and I could read the coil itself for markings but that clearly means the + (pos) on coil goes directly to distributor.
No ballast is needed on 6V ingitions - that's to reduce voltage to 6V for 12V systems once running to save points if I recall which is getting old too * By that you should see full votage to points when cranking and part voltage when running if thru a ballast resistor. Less than 6V probably won't fire.
If somehow "ballasted" right at the new coil it may need to be removed or another used. Any coil from any 12v car with points that I know of could work - untested but told so.
Battery cables: Don't use anything but FINE STRANDED ONE GAUGE WIRE. Seek real copper even with the higher price. Ground can be a massive braided strap and gauge counts big time in 6V systems - the real reason for 12v was it only needs 1/2 the copper.
Compression: If it ran a few weeks ago it's probably fine. The exact pressure could be elusive but I'd guess you'd see about 120ish on fourth compression stroke, increasing from the first to that. It would be momentarily higher while under operating speeds.
The slow cranking: Normal! It's flaming magic to me how an engine cranking so slow will start but they do??
Point gap guess: .016 or .017 - shouldn't be fussy - know that gap gets smaller over time and timing advances as it does that. Minimize that by applying a smear of dielectec (silicone) grease on leading edge of nylon that rides cam for points - NOTE - LEADING EDGE! You may find points with a felt oiler on wrong side for something newer by now.
More notes on pos Ground: Everything will test with test equipment for 6V in this case if you just keep in mind everything we now normally think of as ground will show positive. Mind warp but is so.
You can jump start 6V vehicles with 12V batteries AYOR but leave anything with light bulbs or if with a radio OFF. Starter itself can take it no problem and will spin like nuts!
My own is a GM based block custom made for John Deere using Delco named parts everywhere which is handy now. I've never converted to 12v as it never gave me enough trouble to bother. Also never went to negative ground as starter drive would need to be changed and not sure if I can find one so easy.
A must have if you don't!! :: Right now at WallyWorld they sell a 6 and or 12V "Battery Maintainer" which does do float mode even for 6V batteries! I've seen them for ages for 12v but was just on or off when put to 6V. This one will float - meaning you can just leave it on and it will come on and off by itself as needed using insignificant power to just leave it on. This is a charger but just at a very low amp rate. I've never been able to get a good two whole years out of 6v batteries with the random use my own gets - can be many, many months without touching it. Like any lead/acid batteries drained to flat don't like it AND if it gets caught in cold that way they absolutely do freeze and can self destruct - even crack the case!
Good luck. I can check my own original ign set up to compare which way what goes again if you are unsuccessful at getting it running. Should be all the same concepts,
T
(This post was edited by Tom Greenleaf on Dec 24, 2008, 7:21 AM)
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Loren Champlain Sr
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Dec 24, 2008, 1:58 PM
Post #3 of 15
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Re: 51 Chrysler 6 cyl
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The electrical box? Surely, this has a mechanical choke? Can't imagine what the wires would be going to. Most of the old 6 flat heads had a hole in the engine/bell housing area at the rear of the engine. The trick, not being an electrician, will be getting a timing light that works with 6v, pos. ground.
Back when,...battery companies made 8V batteries just for the starting problem. Unsure if they are still available.
Okay, I'm dating myself.
Loren
SW Washington
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Tom Greenleaf
Ultimate Carjunky
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Dec 24, 2008, 2:33 PM
Post #4 of 15
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Re: 51 Chrysler 6 cyl
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Loren - May not be too many of us who recall these pups! Pos or neg ground alone for lights doesn't matter but a powered timing light would want 12V for power to "enhance" the light. Voltage in plug wire is about the same so lights that don't need boosting work just fine - bet I still have one!
If you are brave enough you can just use a test light and turn the engine by hand and watch the test light for when it goes off at the mark watching for #1 to line up. SLOW is key as engine could start or fire! AYOR with that way or have cap and rotor off while trying that if you know you are approaching #1.
Now I'm getting confused about which terminal on coil goes to dist. It may still be the neg, (-) or marked ) (dist) on the orig coil. They can work backwards I think and behave but everything must be backwards for the whole circuit.
Been way too long but I recall you can check the direction of the spark with a lead (graphite really) pencil in the line of spark and it's going in the direction of the flash if the lead point is in path of the spark it will glow downstream from pencil head. Plugs will fire either direction - I do recall that much and not sure it matters??
T
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Loren Champlain Sr
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Dec 24, 2008, 2:43 PM
Post #5 of 15
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Re: 51 Chrysler 6 cyl
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Ya got me on the coil polarity! If it's backwards, the pattern on the scope will be upside down, shows up like a sore thumb! Good luck finding a scope that will work on 6V pos. ground. I remember installing a stereo in my '40 Ford when I was a kid. Let the smoke out of that sucker in a heartbeat. (I was, probably 14 or 15, and remember just sobbing..all that money, literally going up in smoke) LOL. Seems that my '61 MGA was pos. ground, also. Hmmm? And, I'm even older than you! If that's possible? LOL.
Loren
SW Washington
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Guest
Anonymous Poster
Dec 24, 2008, 8:11 PM
Post #6 of 15
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Re: 51 Chrysler 6 cyl
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Maybe you guys can work with me on this one. Its obvious we are dealing with a positive ground system. The coil is sealed and naturally ungrounded.
So if one attaches the wires either way on the coil it cannot be to a ground. In a normal negative ground system the lead from the ignition switch goes to the positive post on the coil and the negative post is attached to the points/condensor.
The only time the ignition system is grounded is at the electrode when spark occurs.
So if the coil is ungrounded as is the points and condensor. The wire coming from the ignition switch doeant matter if its positive or negative. It it only matters that its attached to the positive side of the coil. Then the negative is attached to the points.
I am thinking this is correct. Just like a light bulb. it doesnt matter which way politarity runs through it. On a coil it only matters which way the current flows.
Does anyone think Im on the right track?
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Norman@two2cool
Novice
Dec 24, 2008, 8:18 PM
Post #7 of 15
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Re: 51 Chrysler 6 cyl
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Sorry, I didnt log in. The last post was from me. Thanks for everyone help
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Norman@two2cool
Novice
Dec 24, 2008, 8:28 PM
Post #8 of 15
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Re: 51 Chrysler 6 cyl
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The electrical box? Surely, this has a mechanical choke? Can't imagine what the wires would be going to. Most of the old 6 flat heads had a hole in the engine/bell housing area at the rear of the engine. The trick, not being an electrician, will be getting a timing light that works with 6v, pos. ground. Back when,...battery companies made 8V batteries just for the starting problem. Unsure if they are still available. Okay, I'm dating myself.
The electrical box has wires coming from different areas. One was from the ignition. The wires exiting this is connected to two areas on the carb. The carb has a manifold heated choke and isnt electrical.
One wire attached to something in the bottom of the bowl. the ohter wire connects to a post at the lower part of the oppisite end of the carb.
This is my fathers car. he was driving it daily for fun. Then it wasnt started for a few weeks and wont start now. Im a fix it all while youre there kind of guy. especially when you cannot easily pinpoint a problem. I grabbed the plug wires and was getting some leakage in my hands. I knew this is drawing away some of the spark so i changed them. The starter was slow so we helped thaty a little by changing to all big battery cables and had the starter freshened up. I know that helped.
It still wont start. I did remove the plugs and placed number one plug so it would fire. Put my thumb over the plug hole and it fire when compression hits. This doesnt mean its not off a tooth or something but close.
Does this engine have a timing chain or is it gear to gear?
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Loren Champlain Sr
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Dec 24, 2008, 9:23 PM
Post #9 of 15
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Re: 51 Chrysler 6 cyl
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>>The electrical box has wires coming from different areas. One was from the ignition. The wires exiting this is connected to two areas on the carb. << I can't for life of me figure what those two wires would be for. They surely didn't try electrically heating the fuel bowl???? I did find an old Motors manual out in the garage. Here's some specs if you don't have them: Plugs .035, points .020 (35-38 dwell), firing order 153624, timing mark=second line before "0" on the vibration damper. The timing procedure is a bit weird: Bring #1 piston up on its compression stroke and stop when the pointer on the timing case cover is in line with the mark mentioned above. Loosen the distributor and rotate until the points close. Then, turn it the opposite way until the points just begin to open, tighten the dist. To compensate for octane being used, it may be necessary to alter the timing slightly. (Hey, it really says that).
The carb; Need to know what brand. Carter, Stromberg, Zenith, ect. Might be able to find some more info.
(116hp @ 3600rpm)
Engine is chain driven, btw.
Did a little more looking; Looks like it's going to be a Carter WCD or Carter BB, but neither are showing any electrical connections.
Loren
SW Washington
(This post was edited by Loren Champlain Sr on Dec 24, 2008, 9:34 PM)
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Guest
Anonymous Poster
Dec 25, 2008, 7:34 AM
Post #10 of 15
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Re: 51 Chrysler 6 cyl
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Loren,
It would make sense to turn the distributor in the direction the rotor travels to close the points?
Then turn it oppisite direction the rotor spins to open them? Then this would be just like it was firing.
I also have a aircraft ignition timing box. I can easily attach to the dist wire and it will light or buzz when Im dead on points opening.
I will take a look at the carb. to see what model/manufacturer it is. Also the connections dont look dainty. They are doing something inside of the carb for sure. Allmost scary.
The carb was working fine. if it wasnt a good newer generation one barrel would be on it.
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Loren Champlain Sr
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Dec 25, 2008, 8:59 AM
Post #11 of 15
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Re: 51 Chrysler 6 cyl
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Norman; Is there any way that you could take a couple of pics of that electrical box and the carb, showing the wires?
Loren
SW Washington
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Norman@two2cool
Novice
Dec 31, 2008, 9:37 PM
Post #12 of 15
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Re: 51 Chrysler 6 cyl
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I will try and take pics by the weekend. I got busy at the shop.
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Mar 24, 2009, 6:15 PM
Post #13 of 15
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Re: 51 Chrysler 6 cyl
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I have pics of the carb will try and post soon. It seems this car is out of time. It is backfiring out of the carb.
Weeks before it stopped running it sgtarted running a little hot. I believe this was due to it skipped time. Then it finally got so far out it quit.
Does this engine have a timing chain? Gear to gear? Online I see it keeps refering to a timing belt but not much info.
Can anyone direct me to where I can find parts for this engine?
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Norman@two2cool
Novice
Mar 24, 2009, 6:21 PM
Post #14 of 15
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Re: 51 Chrysler 6 cyl
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This car sure cranks well on a 12v battery. I disconnected the regulator before doing so. Whats needed to be done to change this car to 12 negative ground? If I get rid of the generator and add a delco 10si self exciting altenator, change the bulbs and put an internal resistor coil to take place of a ballast resistor. What else would I need to do?
All help will be appreciated.
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Loren Champlain Sr
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Mar 24, 2009, 6:29 PM
Post #15 of 15
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Re: 51 Chrysler 6 cyl
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I had a '40 Ford Coupe that was 6V positive ground. I changed it over to 12V neg after many years of problems.
EVERYTHING electrical has to be changed. Heater, wipers (if not vacuum), all bulbs, guages, ect. When I did it, I also rewired everything as, originally, all the wiring had a 'fabric' type of insulation, rather than plastic. Starter will have to be replaced, too.
It's a heck of a job, but can be done. Fortunately for me, Ford stuff is very obtainable. The older Chrys. stuff is, many times, made out of unobtainium.
Loren
SW Washington
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