The Stovebolt Site Forums The Parking Lot Big Bolts no spark at plug

I first bought a 1954 6400 about 7 years ago (95% sure it is a 261ci), and asked this forum and a couple of friends for help getting it started. I spent hours with lots of clean-up, new battery, points, plugs, wires, rebuilt carb, etc and had a valve job done. I got it running, driving (no brakes), and the dump bed was working. I was moving and had to sell it about 4-5 years ago. I sold it to a guy who did nothing with it--it just sat for 4-5 years. I recently came across his number and was able to buy the 6400 back. I got it trailered home and cleaned the negative cables for ground, cleaned the points with a bit of fine sand paper, scuffed up the cap at the connections, and charged the 6-volt battery. It cranks (slow) but I cannot get a spark. I tried putting the old coil back on...still no spark. How can I check the spark at the points? With the old 6-volt, it cranks slow, but there should still be a spark--right? I have gas at the carburetor. What are the next steps for me to troubleshoot? Thank you.

Be sure there is voltage at coil positive. That's first.

Check for the presents of all the components inside dizzy. Make sure you have the right cap. There was a cap change. Rotor may not contact dizzy center lug. You don't really know what the guy or his son did or started to do. They could have forgotten. Take nothing for granted. What you did back then is no longer valid. Could be the condenser or the points. If you are sure there is no spark at plugs. Work backwards from plugs to find a spark. . Very slow crank is not normal. This needs a simple 12V conversion. Look at our tech tip section for how-to convert. There are also 36 pages for a search on "no spark" in our search function......... read the one's that apply. Lots' of tests listed there. Saves us going over it again. Report if you still need help after checking above stuff. I will watch to see if you are still monitoring your post. This place is fast and lots of responses sometimes.
You can check for spark at dizzy center tower.

Slow cranking is a possible sign that the engine is tight. Can you turn the crankshaft by pulling on the fan blades with the spark plugs removed? If not, find out why. Take the plugs out, lube the cylinders well with penetrating oil like Marvel Mystery Oil or KROIL, wait a couple of days, and then spin the engine with the plugs removed. Repeat as necessary until the engine spins freely. Extreme load on the starter can load even a new battery to the point that there's no more current left over after running the starter to power the ignition system. Try a quick boost with 12 volts to see if you can increase the cranking speed but don't burn out the starter with extended cranking time.
Jerry

ok, this is the help I was looking for--thank you! I will look at the other posts also.
I notice the new rotor did not match the old rotor and used the old rotor 4 years back. Maybe I should start over and get new condenser, points--I will look at the other posts to troubleshoot.
just to clarify...when you say there was a cap change--does that mean I should specify a specific cap (1954, 261ci), or does it mean that they don't make the previous version and there is a new rotor that goes with the distributor cap change?

Tall cap vs short cap. Rotor must match cap.

You should be able to produce a spark manually. With the cap off, connect a spark plug to the coil using a plug wire. Lay it on a metal surface. With the points open, turn on the ignition and short across the points with a screw driver, momentarily. That should produce a spark.

When I am trying to bring an old motor back to life, I power the coil separately with a trickle charger. That way the ignition gets full voltage while the starter is cranking and after it starts.

Thanks for the help--I got the 6400 running today.

I used the ideas on this post and on other posts (connecting the spark plug to the coil, checking the points with a screwdriver, kroil in the cylinders as I did the first time I bought it). I eventually removed the points (I forgot the points lift over the second screw, so that took a little head scratching). The points contacts had a hard film that I removed with a wire brush on a drill. I think that was the problem, and I understand the system much better, including the cap/rotor suggestion. Once it started, it sounded great--really strong. The temperature gage stayed below 50% and the oil pressure ran about 35 at idle up to 55/57 with the RPMs up medium/high. It went in first gear about 10 feet and I rolled back to the log-stop, since there are no brakes and I am on a hill. The tilt bed also still works, although it lifts just above the cab. I will have to look through the forum for ideas on the hydraulic cylinder for the tilt bed. Also, I was hesitating to convert to 12 volt, but it sounds like the right thing to do. The 6-volt cranks the engine slow (but it will start) and it does not hold a charge. Thanks again!

Thanks for getting back with the solution.🛠