I have a stock ‘31 Model A Tudor, still 6V, positive ground, has the GM alternator upgrade and upgraded NuRex distributor internals. A couple weeks back, the wires from the horn (they were disconnected from the back of the horn) laid onto the back of the headlight bucket and ended up shorting out on the bucket; resulting in burned horn wires and burning the wires into the headlight and plug. Didn’t think it would be a big deal just rewire the horn and lights and I’d be good to go; not the case! The car will turn over but not run. I’ve tested everything (battery, fuse, terminal box, coil, etc…) and think I have it pinned down to the points being shot. I pulled the condenser and it was giving me 0V so I swapped it out but have no voltage at the points. Which leads me to my question, can points get fried and show no voltage? Was wondering if when the wires shorted at the headlight, did that wipe out the condenser and then take the points with it. Apologies if this seems simple but electrical is not my forte by any means so I’m fumbling through this and it’s driving me nuts!!! Any insight and help would be greatly appreciated! Hell, if any HAMBers are in the Fresno CA area and want to help me out, I’d be happy to buy you lunch! Haha!
Do you have a voltmeter? If so, check that the points have 6V on them when open . (this is checking the side of the points which has the wire coming from the coil.) If they don't, check that you have 6v at the neg. terminal . of the coil. If you don't, you have no supply coming from your ignition switch.
Try moving the spark advance up and down a few times. You may wind up with the distributor apart and check the connections underneath the top plate. That sliding connector on the bottom sometimes gets corroded. Try posting over on the Fordbarn, you''ll get more help on the stock type stuff. Good Luck.
Remember, the way this is wired....the horn was 'Hot' or energized all the time....the horn button made ground It's the same way with your coil....it is Hot all the time and the ignition switch makes to ground thru the dizzy, plus it is positive ground. Do you have voltage at the coil?
Hey guys…thanks for the reply’s. I’ve tested everything from the battery to the distributor and that’s where I lose power. Coil checks out, terminal box checks out, I have power at the bottom plate of the distributor but I lose voltage at the points (in their open position) with and without the condenser (which is brand new). I going to throw a new set of points in it today just to see what happens. Im more wondering can points actually go bad or get fried?? I know they get dirty and can get build up between the points (which they have been filed and cleaned) but can they actually go bad and just not work?
If you take the wire off of the coil that goes to the distributor, is there voltage on that side of the coil? If there is, it is a problem with the wire from the coil to the distributor If there isn't it is a problem with the coil
I don't use stock distributors on my Model A (s) so I'm not that familiar with them. However, if there is a wire under the breaker plate, check to see if it has burned the insulation and caused it to short to ground. Also, I'll give a little advise that a lot of folks need to know. Research has long shown that filing or sanding points can drastically reduce the life span of points, or cause voltage drops, etc. If you must do that, never use sand paper. It can leave microscopic particles embedded in the contact surfaces and cause them to burn or weld them together. If you must sand or file them in an emergency, use very fine grit (800 grit or finer) wet or dry paper and run a piece of clean white paper between the closed points to remove any contaminants. I carry a new set of points and condenser and tools to change them in all my flatheads. Just in case. Listen to what winduptoy has to say, also.
If you have zero volts with the points open, the problem is in the power going to the distributor, not the points. You should have battery voltage at the point connection with the points open.
OK..I re-read your post....so you have voltage to the distributor, if I read it right. The plate that the points mount on has a wire that runs from the backside/underside of the distributor terminal to the termination on the plate that the points mount on. This wire is likely broken or insulation worn thru and shorted out. Think about it, the whole breaker plate rotates as you adjust the timing...it eventually breaks the wire. If you unhook the linkage from your advance lever and the rotor, the whole plate should rotate to a point where it can be removed. I use TFE "nickel hinge" wire to replace it....I'll try to go take a stock dizzy apart and shoot some photos. It has been awhile since I have worked on a stock Model A distributor....
You also have to remove the distributor cam to pull the plate plus I see that you said you have Nu-Rex dizzy parts....they are just repop stock parts but that doesn't mean that there isn't something shorting to ground in your dizzy(same as having the points closed) so that you don't read voltage at the points, with them open.
Thanks for all the help everyone…I was getting poor contact with the copper plate on the lower half AND the coil was trashed. Should be in good shape now; just need to time it and fire it up! Thanks again HAMB!!!
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