Nu Rex ignition switch

[Mittie Lee 1935]

I Recently bought a 3 position Nu rex. Ignition switch that resembles the original but this one does not popout. My 1931 Ford has a single yellow wire that was attached to the original switch. I do not plan to use the Acc terminal on new switch. I hooked up yellow switch from my terminal box to the coil terminal and when motor wouldn’t start I hooked it to Batt terminal and car still would not start. Help, what am I doing wrong? I did buy a replacement cable that would run to the distributor from new switch and it has a black wire.Do I have to use this cable and if so where does the black wire go? If I don’t have to use metal cable does screw in at distributor have tobeplugged to keep moisture out?

[christian]

if you are using the stock wiring harness you should have a red wire going from one pole of the coil to the ignition switch. the other pole of the coil is connected to terminal block with a short black wire.

[Mittie Lee 1935]

The original switch had only one wire [yellow] from terminal box attached to it and shielded cable going to distributor. Should I just run a wire from negative side of coil to batt terminal on switch any a second wire from positive side of coil to coil terminal on switch? Will this work or do I need to interrupt the circuit and how would I do this?

[Y-Blockhead]

You need a wire from the junction box, to the negative side of the coil. Then a wire from the positive side of the coil (if you still have positive ground system), thru the switch and then connected to your points in the distributor.

[Mittie Lee 1935]

Thanks for the reply. So the instructions that came with the Nu Red switch says to run wire from junction box (was wire that was attached to original switch) to Batt terminal on new switch. So if I attach anew braided cable from switch to distributor and hook up black wire that is on one end to coilterminal, that should work right?

[Y-Blockhead]

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Can you post a picture of your Nurex instructions. What you proposed does not sound correct.

[Jim/GA]

Originally Posted by Mittie Lee 1935

Thanks for the reply. So the instructions that came with the Nu Red switch says to run wire from junction box (was wire that was attached to original switch) to Batt terminal on new switch. So if I attach anew braided cable from switch to distributor and hook up black wire that is on one end to coilterminal, that should work right?

No. What you describe above will not work.

If you want to connect a wire from the junction box to the Batt terminal of the switch, then the second wire coming off of the switch (screw labeled Ign?) must go to the Negative post of the coil.

Then connect the shielded wire from the distributor to the Positive post of the coil. That's assuming your battery is installed with the Positive post connected to the frame (positive ground car, as original)..

There will be no black wire connecting from the terminal box to the coil with the above wiring scheme.

So that you understand what you are doing, the above wiring scheme is NOT the way Ford wired them from the factory. But it will work. It all starts with you deciding you want to connect a wire from the terminal box to the switch. Once you do that, the rest must be connected as I describe.

[Mittie Lee 1935]

Thank you Jim and everyone for the help.

[Mittie Lee 1935]

I’m not committed to going from the switch to-the terminal box I just want it to work. I didn’t understand that a wire was inside braided cable and ran to points. So reattaching a new braded cable by screwing into distributor what terminal on back of switch (Batt or Coil)would that black wire inside cable attach?

[katy]

This may help:

[Jim/GA]

Originally Posted by katy

This may help:

This is a great drawing. Very simple.

Note that this is the way Ford originally wired the car. The key switch is installed in the wire that runs from the coil + post (red wire on a stock car) to the points in the distributor (shielded wire screws into the side of the distributor).

This is not the wiring scheme that Mittle Lee said he was using in his original post. He indicated that he was installing the switch in the wire between the terminal box and the power feed to the - post of the coil.

Either scheme works.

[Jim/GA]

Originally Posted by Mittie Lee 1935

I’m not committed to going from the switch to-the terminal box I just want it to work. I didn’t understand that a wire was inside braided cable and ran to points. So reattaching a new braded cable by screwing into distributor what terminal on back of switch (Batt or Coil)would that black wire inside cable attach?

Then connect the shielded wire from the distributor to the Positive post of the coil.

.

[Y-Blockhead]

This is the way the wiring should look if you are wiring your ignition the way Nurex suggests (and I stated back in post #4) with the switch before the coil. As mentioned, not original.

[Mittie Lee 1935]

Originally the pop out switch had the braided cable going to the distributor and a wire attached from the bat side (- ) of the coil. 2 other wires ran from the terminal to the amp guage and the car started. I removed the old switch and installed a Nu-Rex with 3 terminals, Bat, coil, acc. I also installed a new braided cable running from distributor through dash and into car. Would it be normal to connect the black wire inside cable to switch and to which terminal. Now the second wire from the switch would go from what terminal to where? I’m totally lost. Please help. My number is 903-948-8275. Charles Steen

[Bob C]

Are you running 6V positive ground or 12V negative ground?

[Jim M]

Katy's diagram is spot on. I used it a everyting wors like a charm!

[rotorwrench]

Ford put their Electro-Lock switch in to control the breaker circuit of the distributor. A power wire then connected the load side (generator wire) in the terminal box with a black wire to the power terminal on the coil.

A person can still do it this way by connecting the breaker points wire (shielded) to the switch bat terminal. The coil terminal on the switch would then be connected with the red wire to the distributor breaker terminal on the coil (+ side). Leave the coil power side (negative) connected as it originally was. It will at least look stock that way.

[Mittie Lee 1935]

The strength of the Model A Club is the members! I was a member from 2002-2012 and after I sold my 1929 Tudor Sedan (big mistake) I dropped out. Now in 2024 as the 2 week old proud owner of a 1931 Coupe, I have rejoined and almost immediately needed big help in starting issues with my car. A great member on this forum, JIM CANNON reached out to me and via FaceTime patiently stayed with me for over 5 hours today to get my car Ludie Belle II TO RUNNING AGAIN. Thanks Jim for your dedication to the club and especially this particular member. Thanks again to everyone on this problem for your advice!!! Yup, the Model A Club of America is a great club !!!!!!!

[Tiger2]

Originally Posted by Mittie Lee 1935

The strength of the Model A Club is the members! I was a member from 2002-2012 and after I sold my 1929 Tudor Sedan (big mistake) I dropped out. Now in 2024 as the 2 week old proud owner of a 1931 Coupe, I have rejoined and almost immediately needed big help in starting issues with my car. A great member on this forum, JIM CANNON reached out to me and via FaceTime patiently stayed with me for over 5 hours today to get my car Ludie Belle II TO RUNNING AGAIN. Thanks Jim for your dedication to the club and especially this particular member. Thanks again to everyone on this problem for your advice!!! Yup, the Model A Club of America is a great club !!!!!!!

Any chance you could post a drawing of what you ended up with please? I have the same opportunity it seems. I just replaced the ammeter, Nu-Rex switch, distributor cable & ignition harness. Now the car won't start. Thanks for your consideration!

[Jim/GA]

Originally Posted by Tiger2

Any chance you could post a drawing of what you ended up with please? I have the same opportunity it seems. I just replaced the ammeter, Nu-Rex switch, distributor cable & ignition harness. Now the car won't start. Thanks for your consideration!

We reconnected a couple of wires where they attach to the switch and where they attach to the coil. That's about it.

You will also want to be sure your cable going into the distributor is screwed in "far enough" but not "too far". Too far and it will ground out inside the distributor and you get no spark.

Do you have a little test light that clips to a ground, that you can probe around and touch various wires? Those can really help you diagnose electrical problems. Insert a piece of paper in the ignition points, so that they do not make a connection, and start looking at where you have power with the key off and on.

[rotorwrench]

The new type switch can be connected to either control power from the battery to the coil or the ground pathway between the coil and the breaker points in the distributor. We would need to know which way the new switch is connected to give the best advice.

Ford used the Electrolock switch/cable assembly to control the ground pathway from the coil to the breaker points in the distributor. Modern systems control the power to the coil from the battery.

The distributor also has the little wire that connects the lower plate to the upper points plate. It has to flex when the spark advance control is changed so it can be a problematic at times. A bad condenser can kill the ignition function so always keep a new A&L spare around for testing.

[rich40701]

I just installed the Nu Rex ignition switch but luckily my A had been converted to electronic ignition before I got it, and a similar switch was used with two wires. I like the original look of the Nu Rex ignition switch. The site touts the switch to be made in USA but after receiving the switch says made in Mexico assembled in USA or vice versa. Made in USA should mean "MADE IN USA", period.

[Rob Doe]

Guyz, Katy's diagram in post 13 shows the power side of the coil as the - neg and the distributor / points side as + pos. It also implies a 12v system. Unless he has a 12v positive ground system, his coil polarity would be reversed???? Am I cornfused????

[Y-Blockhead]

Originally Posted by Rob Doe

Guyz, Katy's diagram in post 13 shows the power side of the coil as the - neg and the distributor / points side as + pos. It also implies a 12v system. Unless he has a 12v positive ground system, his coil polarity would be reversed???? Am I cornfused????

Rob, sorry for the confusion. I posted that picture in post #13 and it is incorrect. I have deleted it. Thanks for keeping me honest.

[Rob Doe]

Tiger2, post 19:

The diagram in post 13 is nicely drawn. It is easily understood by experienced Model A persons. It is lacking a few details that will be needed by the beginner Model A person that is wiring his car for the first time.

The diagram shows a 6 volt battery with the + pos post grounded to the frame. It is important that the newbie know what battery and which cable is grounded to the frame. 12V or 6V, and Pos + or Neg - grounding is being used. A 12V, negative ground system requires a reversal of the wires at the ammeter and the coil from those of a 6V + positive ground one.

Professional wiring diagrams (for those with formal training) are generally drawn with no relationship of the components to their actual position in the vehicle. Components are identified within a symbol. Actual component positions in the car might be commented on the diagram in a convenient location. IMHO, this drawing is a duke's mixture as it depicts renditions of the components and their somewhat relative positions in the vehicle, which actually helps the beginner. However, it lacks the markings of + plus and - minus on the key components. The perspective of the drawing seems to be from the front of the car looking toward the firewall.

Assuming it is the backside of the ammeter that is depicted, the two wires attached there should be drawn with one crossing over the other. The ammeter will read backwards if these connections are incorrect side to side. The wires that run from the terminal box studs to the ammeter on a stock Model A are not yellow and yellow. They are yellow and yellow / black stripped. Refer to the front face of the ammeter for proper connections.

At the ignition coil on a stock Model A, the short black wire that is sourced from the terminal box powers the primary coil winding. It must attach at the - neg post of the coil and the opposite post, the + pos post must power the ignition points via the switch, else the polarity of the spark at the spark plug will be reversed causing a weak spark. The car will run, but it may start and run poorly if there are poor connections or weak components. There are methods to test the polarity of the ignition.

There is a service bulletin which moves the source of the short black wire, which powers the coil primary from the yellow wire / terminal box stud to the yellow / black stripe terminal box stud. This bulletin can be found in the November 1929 chapter. This change causes the opening and closing of the ignition points to be depicted on the ammeter when starting the vehicle and at lower rpms. This is useful when diagnosing ignition problems. The newbie should make sure he is wired accordingly.

Snyder's Model A Parts sells a very good 11 x 17 wiring diagram, which is produced on a rugged plastic sheet for a small amount of money. It depicts the last of the wiring changes for the Model A 28-31.

https://www.snydersantiqueauto.com/p...6763&cat=41801

I hope someone finds this post helpful.

[Tiger2]

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Rob Doe Post #25. Thank you for your information! It indeed was helpful. Jim Cannon suggested that I may have tightened the Nu Rex armored cable into the distributor too far, When I backed the cable out a bit I felt and heard a "click" and just knew that things were improving. My 1931 coupe started right up with no blown fuse and no smoke. Thanks again fellas for taking time to give me direction on this.