Advise needed on ignition problem

[colonelpowers]

I am working on a late friend's 17 T. The car was running fine last fall but for some unknown reason his son left it outside under a tarp all winter and now it is not fine. It took forever to get the car started and when it finally did start it was only running on the middle two cylinders. I thought that it might be the coils so I switched them around. Still only running on the middle two. A note about the coils, due to being out in the damp all winter the wood of the coils has swelled so that you can barely get the coils out at all. The wiring all appears to be undamaged. I think I will try to disassemble the contacts in the coil box and clean everything. If that doesn't work then I may try running new wires from the timer to the coil box (though I don't think that is the problem). Any other ideas? One other thing to mention that I thought was odd, the car wouldn't hit at all with the spark retarded. The times the car finally started the spark was almost fully advanced. Maybe it has something to do with it only running on two cylinders but I don't see how.

Any help will be greatly appreciated.

[walber]

As this seems to be primarily an ignition problem, I would do the following: Bring the coils inside to dry them out. Clean and dry as much of the coil box as practical. I would also remove the timer - inspect and clean it, lubricate if it's one that needs that. Pull the plugs and clean or replace them as appropriate. With things dried and cleaned, I would rest the plugs on the top of the head, turn on the ignition and slowly pull the engine through with the hand crank to watch for spark on the coils. Would also check the timing to ensure the #1 plug get spark when the piston is just past top dead center when the spark lever is retarded. Hopefully that will help identify the problem(s).

[TXGOAT2]

In addition to the above, the point contacts on the coils may be corroded, and the coil box contacts may also be corroded. Even a near-invisble amount of oxide on the points or the coil box contacts can cause trouble. Also, it's possible you have sticking valve issues or light rust on the valve faces. Moving the ignition switch through its various positions several times may also help. (Won't hurt) It sounds like your car was subjected to high moisture that got trapped under the tarp.

[John kuehn]

Did you clean up the timer? Could be the coil box got damp also being out under a tarp.
Determine if it’s the coils or the same cylinders not firing. Swap the coils around on a cylinder that’s getting fire. If all the coils will fire on the same cylinder the coils are OK and the trouble is in the wiring connections, dirty timer, or the coil box.
Use a hair dryer or some type of dryer to dry out the coil box.

Long term moisture isnt good for a T coil box and especially if a T that has a wooden firewall. You said it’s a 17 and it may have a wood firewall. Maybe the contacts inside the coil box? The timer wires shorting out close to the timer when it rotates?

Good luck.

[TXGOAT2]

Did you remove all gasoline from the tank and put in fresh gas?

[colonelpowers]

Here is what I have done so far: I cleaned the carb, the timer, the plugs, and the wire ends. I was driving my 27 so I pulled my coils initially to start the car and it was only running on two cylinders. I reinstalled the original coils (which my late friend son had admitted to trying to adjust by feel) and restarted the car. I used a spark tester, the type that reads through the plug wire insulation, and got a good strong spark on the two middle wires. The 1 cylinder had barely a flicker on the tester and the back cylinder showed no spark at all. Several times I swapped the coils around but the dead cylinders stayed in the same place.

The timer is the roller type and cleaned up very nicely. I haven't checked the timing, but since it was fine in the fall I don't see how it could be out of time. If you think it is important I could check it out. Is there any way the timer cover could be allowing those cylinders to ground out. It looks good inside but it is old. The timer wires are clear of everything and at least the ends that are visible look fine.

[TRDxB2]

If you swapped good coils and 1 & 4 still didn't show spark to them, then there are three possible issues related to the circuit. 1. The spark plug wires are bad or spark plugs not grounded for some reason (doubtful); 2. Something is wrong with the wires from the commutator to the coil box for #1 & #4 (swapped wires, frayed insulation shorting out?); 3. Something wrong with the commutator (firing order 1,2,4,3) which you noted some differences with advancing and retarding. The first test I would do is to see if there was continuity to the wires on the coil box from the commutator in the proper firing order by disconnecting them and slowing hand cranking the engine.

[Chris Barker]

The coil box may be damp and conducting the sparks from coils 1 and 4 to ground.
With it running on 2 cylinders, do the other two coils fire? You can safely touch the contacts and feel them move.
If they are all moving, it may well be damp wood. If not, look at the timer, coil box contacts and wiring.

[Russ T Fender]

I had a similar issue after touring two days in heavy rain. Inspected everything and could find no issues. In desperation I swapped out the roller timer case and the problem was solved. Inspection of the timer case I removed with a magnifying glass showed a fine hairline crack in the insulation that was causing the problem.

[Charlie B in N.J.]

You swapped the coils and the same two cylinders fired. It's not the coils. If the wiring looks OK as in didn't get eaten by varmints your next step is the timer.

[John kuehn]

Charlie B is right about the varmits! Critters can and will do damage to a cars wiring! They love chewing on wiring. We have a Honda CRV that has its headlight wiring chewed into in different places in the shop right now. It happened 3 days ago. Also 2 years ago my Toyota Tundra’s gas line leading into the gas tank got gnawed on and poured gas all over our driveway .
Sorry for the rant but the T’s trouble is in the wiring or in the timer. It seems that way anyway.

[colonelpowers]

I just wanted to give an update on how I fixed the problem with my friend's 17 that was missing on the back cylinder. This may help someone else in a pinch, I don't know. I had checked the coils, replaced the wires to the timer and the plug wire, took the coil box out and cleaned all the contacts but in spite of everything it still wasn't getting fire on the back cylinder and I just knew that somehow the problem was in the coil box. Last night I finally had a stroke of genius, all I needed was a piece of inner tube and some heat shrink tube. This morning I removed the two contacts from the coil box that correspond with the rear cylinder. I cut inner tube to go between the brass contacts and the back board of the coil box. The bolts were sheathed in shrink tube and then everything was reassembled. The problem is gone. I still don't understand how enough voltage was lost between the coil and the end of the porcelain insulator to cause a misfire but this is a cheap and simple repair that works. Maybe it will help someone.

God Bless!

[Scott_Conger]

sounds like you insulated things from carbon tracks. Don't underestimate path of least resistance...under compression, the spark jump at the plug may well be of greater resistance than the carbon track and it sounds like it was.

The final fix is a rebuilt coil box, but your fix should last until the next carbon track somewhere else does you in.

good for you for finding it and even more, for telling the forum of your findings.

[Steve Jelf]

The bolts were sheathed in shrink tube...

I gather the coil box still has its old wooden back panel. Especially if it has gotten wet at some time, you can have carbon tracking that grounds a circuit. I expect the shrink tube is insulating the bolt from a carbon track in the wood. This is why I always install John Regan's FP kit in a coil box.

[TXGOAT2]

It doesn't take much to allow the high tension to find a way to ground. On the primary side, you'd think 6 volts would be fairly easy to keep corraled, but then a Model T ignition primary might see up to 30 volts when running on the magneto. Old insulation can harbor internal defects that allow current leakage even if it looks good. Such defects may not cause issues under some conditions, and yet cause serious problems under other conditions, particularly wet weather. Wooden insulation may have been exposed to salt, rodent urine, or even battery acid in the past. Sometimes metal oxides can leach into wood and degrade its dielectric properties. Wood may have had paint applied that contained conductive pignments.