No fire at the plugs

R

Royal Ryser

Well-known member
I need help once again. I have a 36 tudor with a 59ab engine, 6 volt system, positive ground. The coil is a 78-12024, I think. I have removed from the engine the wiring, plug wires, coil, condenser, ignition switch, fuse block and resistor and the ammeter from the dash (along with the other instruments.)
I have replaced the coil with a rebuilt from Skip along with a new condenser, new plug wires, new fuse block and resistor, nos floor starter switch, new battery and battery cables. The ignition switch has been disassembled, cleaned and reassembled.
I have wired the car just enough to test run it. I ran the positive battery cable to a good clean ground. I then ran a 12 ga wire with new wire connectors from the battery to the ignition switch, the resistor and the coil. I did not attach the fuse block or the ammeter.
When I checked the spark at the plugs, I got a weak spark on one plug and nothing on 3 others. The battery is new, has 6.5 volts. At the coil I got 3.3 volts through the new resistor. I found no voltage drop though the ignition switch.
I've spent about 2 hrs reading old posts about the ignition system. Seems like there is sufficient voltage at the coil. However, the new resistor got very hot as I was testing the system.
So, where do I go from here? I have checked, cleaned and tightened all connections.
Sorry to bore you but I need help. Thanks to all.
Royal Ryser
 
You seem to have it wired correct. It is normal for the resister to get really hot and drop the voltage to 3.3 volts at the coil. It sounds like you got something going on in the distrbutor.
 
look at the rotor button, look for carbon tracking, remove from distributor and look down the inside of it for the same
 
The more research I do, the more I realize how challenging the ignition is on these early V-8s. Knowing little, I'm responding assuming you have the "diving helmet" distributor versus the "crab" style or later, more modern distributor. If not, some of these things are still worth a look.

(EDIT: something tells me the 59AB had the "crab" style distributor as standard, but I'll leave the post as is just in case. I guess I could have asked before I launched into the following reply. I also linked the "crab" style firing order for reference.

I'm a novice, but will pass on what I've heard, as I've had some challenges with mine as well. Not only is your point gap (and dwell) crucial, but so are the ignition cap terminal gaps as well. It seems if it were the points, you wouldn't have spark at all but it's worth checking those (sometimes one of the point springs will break which grounds the points out, thus, no spark). The rotor could have bad/corroded/chipped terminals. The back (towards the firewall) terminal supplies spark to two plugs on the right of the block and two on the left (1, 4, 7 and 6) and the front rotor terminal supplies spark to (2, 3, 8 and 5) See the link below for the firing order. You can use that to help trouble-shoot that possibility. I've also put a timing light on each plug wire and the coil wire to detect spark in the wire as a short-cut. My old 12 volt Sears light works on my 6 volt pos. ground system with no problem.

The next crucial variable is the gap between the 8 cap terminals and the 2 rotor terminals. To keep consistent spark on all plugs, that gap should be as close to 10 thousandths as possible. Those can corrode and sometimes fail and cause an arc which can be seen as a trace inside the caps. When replacing the caps and rotor, you have to file down all 8 pointed terminals to allow the rotor terminals to have a gap and pass by but the angle has to stay intact for uniform air gap. If you don't file them, turning the engine over will break the cap and/or rotor terminals. You may be able to just file the 2 rotor terminals, but I've never trusted that the cap terminals were a uniform length.

Another issue (assuming your wires are good) can be the plug wires being loose and not seated in the caps. It's VERY difficult to work on the caps and wires with the distributor in the car (definitely have to remove it for points/rotor change) so the best solution is to unbolt the metal wire looms, the vacuum line from the distributor, unbolt the distributor and pull the entire set out together, looms, wires, distributor and all and work on it as a complete unit.

I've heard your best bet is to let someone set your distributor up for you on a bench for the point gap, dwell and timing and I'm sure there's several here who can instruct you on that.

These are just some things that have been passed on to me. I hope I'm accurate and clear in my descriptions and also hope you find it helpful. Anyone please feel free to let me know if I've said something that isn't correct. As I said, I'm still a novice, but I'm learning more every day, thanks in part to many of you here.

Best of luck!
Dan
Link for firing order:
http://www.google.com/imgres?imgurl...lG5GE9QTIsIGQCg&sqi=2&ved=0CCwQ9QEwAA&dur=332

"Crab" style link:
http://www.google.com/imgres?imgurl...dKAjYI2MsasrM:;W7zssJnDn_mwNM;ndKAjYI2MsasrM:
 
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Thanks to all for the help. I now have good spark at the plugs but I'm getting some backfire. I'll check to be certain I have the spark plug wires in the correct order.
 
Dan gave you a good check list. Make sure both sets of points are gapped correctly with the rub block set at the peak of a cam lobe. After correctly setting the gap, turn the shaft to make sure both sets of points are opening and closing properly. Put a light coating of lube on the cam. Make sure you have the correct inner caps and rotor for the model/year helmet distributor you are using. With the rotor and inner caps in place make sure the rotor terminals are in line with inner cap terminals as you rotate the main shaft. Sometimes the rotor terminals will hit the inner cap terminals and this would need to be corrected. As Dan said make sure the ends of the sparkplug wires are properly fitted into their correct locations in the inner cap holes. The original type plug wires had numbered tin coated spring clips soldered to the ends of the wires. This made it a little easier to get the wires placed correctly. Another thing to check is the fit of the inner caps in the aluminum housing. Some of these caps will not seat all the way and therefore the terminal gaps will not be correct. I've had to lightly sand around the OD on some of mine to get them to fit correctly. Starting with a new condenser does not always mean it's good. There has been lots of fallout with the new ones.
 
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The engine is running; seem to have good spark at the plugs. I did have 2 wires interchanged. That made it run rough!
I really haven't found out why the spark was gone or missing earlier.
Thanks for all of the help.
Royal
 
One thing I did change on my ignition system was to remove some old resistor plug wire ends. When I checked them, they wouldn't pass the current to the plugs or passed very little. I think that was the original problem.
Royal
 
Royal Riser, in this last situation you mentioned, the spark usually finds its way into another lead, and fires the wrong plug at the wrong time. A whole new subject (cross firing)
 
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