VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 6 volt coil for 1929

I have isolated a weak spark problem to be the coil by hot-wiring directly from the battery to the coil and then to the points with a condenser to ground. The coil lasted 250 miles before the spark became too weak to start the engine. The ohms measured 1 ohm primary and 9k secondary, however, the amperage draw according to the dash meter was -8 amps and the repair manual says if it draws more than -3 amps to replace the coil. I ordered a new one and it also measured 1 ohm and about 7k ohms and the ammeter indicated -6 amps the spark was great, nearly one inch long so I put the system together and planned to start it up. Then it occurred to me that I hadn't checked the spark at the points before putting the distributor cap on, so I checked the points by opening them and found the spark was not that hot. I went back to the hot wire system that had given me the hot spark and now it was very small and weak, and the ammeter indicated -9amps. I believe the new coil is now shot also. My question is what brand of coil do you use or recommend? I did buy from one of our suppliers. I am considering ordering a Model A coil, however, I don't know if it would fit in my bracket.
Also, to be sure there was not another drain on the system I checked the ammeter with the coil disconnected and the ammeter did not move.

I have used recently manufactured 6V coils available from O'reilly Auto Parts with only occasional overheating problems. They are not expensive and if they don't work you can get another.

I have documented my overheating problems several times. It only happens with lugging up a grade in the summer. A dose of water on the coil solves the problem. It is avoided by downshifting.

I got my coil from O-reilly's & Advance Auto it was BWD E5 paid around $20 for them. have the same coil in my 1929 and 1930, and recently put one in my friends 1931. and i even bought a spare, granted not all at the same time.

if you keep killing coils that quick i would be looking at other things that could be causing it.

forgot to add: both stores have a limited lifetime warranty on the coils :)

As a follow up. I have checked the ignition system thoroughly and come up with two possible problems. The plugs were heavily carboned and I replaced them. That resulted in a much better spark. The other problem seemed to be an intermittent short from the condenser coil wire to the slot in the cup at bottom of the electrolock. The shrink tube insulation had slipped back far enough from the terminal to allow occasional shorting. I retested the three coils I have and the system works fine with all of them. Now that the ignition system is working good I am curious why the plugs were fouled with only 240 miles since the engine rebuild. I have leaned out the carburetor considerably and the exhaust seems clean, however, when the engine is warmed up and the car is running the condensation dripping from the tail pipe will leave carbon spots on the cement driveway. I did a compression test and four cylinders are 75 psi and two are 67-68. I increased the valve clearence on those two cylinders to 008" and 010" but that did not change the compression. I am wondering it the carbon could be caused by ring leakage.

Is the carbon on the plugs dry and sooty?
Or is it a little oily?

Dry and sooty. like I said, it's a new rebuild, however, I didn't realize that the carburetor adjusting screw should be turned out to lean the fuel and I had turned it in too far so this accounted for the carbon for the first one hundred miles. The exhaust was so dirty a friend ruined his pants standing behind my car while it was running. I did notice that the plugs were all equally carboned up. When I found out that the screw should be backed out to add more air and less fuel to the mix I backed it out to the degree that I had to increase the Idle speed to keep it running smooth. Now there is less carbon in the exhaust (you can hold a paper towel behind the exhaust pipe when running and it will be clean) but like I said the condensation from the tail pipe leaves carbon stains on the driveway. I will check the plugs again in awhile to see if they are ok. Maybe the carbon was left over in the exhaust system. I am hoping the two cylinders which are a little low will improve as the break in continues.

I expect it will take some long drives at higher speeds to clean out the pipes and muffler.

What is your plug gap? Also, if it’s a new engine have you run it at high and low rpm’s to seat the rings. If it’s a new rebuild, all 6 should be really close in compression.

All my cars, when first started, will leave black condensation on the garage floor. It goes away quickly as the vehicle warms up and does not repeat through the day.

Dave

I also will see some black condensation on a cold start-up. It is due to the rich mixture when you use the choke.

I learned that I could not park my car in the shop with the front pointing out. After I cleaned the front of my toolboxes a few times!

I probably need to do more high RPMs most of my driving does not exceed 35 mph. Plugs are at .040".
The compression readings were the same when first re-built (two cylinders low). I did give them a shot of oil and re-tested which brought the reading up about 1 pound.