The Lady and I just bought a 1949 Chevy 3600 and we're trying to get it started. As far as I can determine our first hurdle is getting some spark. The previous owner drove the truck frequently and took pretty good care of it. Its a used 49 truck but in good shape. It was stored in a garage for 4 years and never started. Here's what we've done; - Engine cranks without starting - Cranking the engine and checking for spark using a grounded sparkplug on several wires. No spark while cranking. - We have voltage (6V) to both (-) and (+) of the coil. - The distributor looks brand new along with the condenser and points. - We repalced the condenser and points. (points were gapped to a loose .020 because thats all we had. Still no spark. - Using a test light, we have voltage from the coil to the points. - We tested the coil with the points closed and attempted to ground it from the center post. No spark. We are thinking the coil might be bad but this is rare. What else can we do to test ignition? Thanks Y'all
The way the coil is charged up and "fires" works this way. There are two sets of wire "windings" in the coil, insulated from one another, but one is wound around the outside of the other. The Primary winding starts at the + small terminal and ends at the - small terminal, but the curent flow continues to the point set. The Secondary winding starts at the + terminal and grounds/exits through the large center terminal. When the points are closed, current flows through the Primary winding, a magnetic field is created, which surrounds the coil, and when the points are opened, the Primary current flow stops, the magnetic field collapses, passing through the Secondary winding, and "induces" a high voltage spike through Secondary coil winding. That high voltage spike passes through the coil wire, to the distributor cap, across the rotor and out through a cap terminal to a spark plug, where it jumps the spark plug gap to Ground. As you can see, jumping the gap produces the spark that give the plug it's name. Now, if anywhere along the way this process is interfered with, nothing happens. In your question above, you indicate you "set the points to a "loose .020"...with that much gap, it is possible that the points are not closing completely enough to allow the current to flow through coil Primary circuit. In which case, there is no magnetic field and no spark. Gap them carefully and to the correct .015"/.016" (as I recall). Make sure you have the point rubbing block on the high point of the distributor cam when doing so. Also, if someone replaced the points, it IS possible that there is a grounding condition at the points, whereby the current flow through the points, intended for the coil, is grounding out at the points, BEFORE getting to the coil, and again, if the coil does not get charged....no spark. Check CAREFULLY, that the wires to the points (+ and condensor) are not touching anything but the points terminal. It's easy to ground one of them inadvertently. It's important to understand that one side (one "point" of the points set) is insulated from the point set base. That is the side fed by the + wire. The other 'point' is grounded through the distributor plate to the distibutor housing, engine, ground cable and back to the battery to complete the circuit. Since the distributor base plate rotates to vary the timing, it has a flexible wire connecting the base plate to the dist housing to insure a good ground. That wire, frequently flexing when the engine is running, sometimes breaks. Usually if an engine that did run, no longer runs, the FIRST place to look for the problem is the LAST place any work was performed. Of course, the cap,rotor, spark plug wires and plugs themselves, all have to be functioning correct too, but it is doubtful that is where your probelm is. I think if you will carefully trace the points circuit, and insure the components are installed and functioning as intended, you will solve this issue. Ray
Remove the small wire going from the ignition coil to distributor. Take a jumper wire and hook to the coil terminal where the wire was removed. With ignition switch on, touch the jumper wire and ground it, then remove it and watch for spark at center wire of distributor (Remove from distributor cap first, and watch for spark with the end near engine block bolt) If you get a spark, the coil is fine. If not the coil is bad. If spark is good coming out of the coil, then distributor points are being grounded, or the wire going to the distributor that was disconnected to test the coil is open.
And DO NOT run it with old fuel !! Setup a temp fuel supply with fresh clean fuel to supply the pump. If the tank smells bad get it cleaned before using it.
Using your test light on the points side of the coil, connect your spark tester to the coil wire and crank the engine. The test light should flicker on and off as the points open and close. If it does, the coil is the problem. You can try moving the coil in the mounting bracket to make certain it has a good ground. If the light stays on, the points aren't grounding which could be the points not closing or distributor not getting a good ground. I'm assuming you set the points with the rubbing block at the top of a lobe. I mention this because it's been almost 40 years since cars were built with points ignition and I've known several good young mechanics with no experience with points that set the gap where the distributor happened to be at the time they set them.
above advice is great...do yourself a favor, find (on line or used book store) a Motor's® Manual for vehicles of that vintage. Hopefully it will cover light trucks, but even if it doesn't, the 216 was in everything back then. Motor's® has an EXCELLENT troubleshooting guide in ever manual. It takes you through every step to ensure you have properly-timed spark, fuel in sufficient quantity, and sufficient compression. With those three things (assuming clean gasoline) you should get a running engine. dj
In case you haven't set points in the past remember that the points have to be set with the rubbing block on the arm of the points in contact with one of the high points of the distributor cam. I've lost track of the number of "I set the points and it won't start" vehicles I have checked where the person changing and setting the points set the gap with the rubbing block against the flat. 51 Chev 6 distributor with rubbing block of points set on high point of distributor cam. Also make sure you have the wire from the condenser in the right spot and not against the side of the housing. As bad as the smoke is here I wish I could afford a road trip to the land of fresh air. I'd pack along my little coil tester and a spare coil out of the 51 truck I have out here.
What MR48chev said is usually the problem, Also new points foul alot especially when your trying to get it running after a long time idle. If the points are set right remove the cap and turn the engine over if you dont see the points sparking then try cleaning them up with a points file or fine sandpaper. if your getting electrical current all the way to the distributor then you should see a spark at the points with the cap off. If you see spark at the points it should start with the cap back on(or backfire be careful!) If you think the coil could be bad then replace it you'll save time and frustration and it isnt that rare for a coil to go bad but it is pretty common that the wires on the coil are not making good contact.
The points shouldn't spark when it's cranking over if the condenser is doing it's job. As Hnstray said in his excellent description in post 2 the points are the switch that controls the build up of the magnetic field in the primary winding of the coil which collapses causing the high voltage in the secondary side of the coil which in turn causes the spark at the spark plug. The condenser serves to absorb the primary voltage when the points open and helps keep a spark from jumping the points at that time.
When you are through testing your points circuit, make sure you put the rotor on before putting distributor cap back on.
As I remember there were 2 different caps that would fit that body,as said earlier if you have the taller one you won;t get a spark at the plugs.
When starting my 50 for the first time I went thru much the same process=replaced everything , coil. points, condensor, wires, cap and rotor, still did not get a spark I could see. Finally cleaned the area around the distributor which must have allowed it to ground cause it fired right off then. As stated earlier be sure it is getting fresh fuel also, it took the fuel pump a while to get fuel to the carb. Great little engine if not abused. Jim
YEEEE-HAAAAA!! IT'S ALIVE!!! Thanks y'all for all the advice. Ray & d2 - Big Props Dudes - We were able to test the coil and confirm that it was functioning properly. Which ruled out the coil, coil wire, and distributor cap. - We gapped the points to .015 - We replaced the plugs from Autolite gapped at .020, to Champions gapped at .035 (ish, I didnt gap them and I cant remember the spec). - We still had high resistance ~600 Ohms with the points closed. So, we cleaned the new points using 800 grit paper which gave us a more consistant contact patch with very little resistance. - One of us held a the plug wire to enhance contact potential... WHOOPS! The engine sputtered to life! WOOOOHOOOOOo!!
Cool enough. That's good to see. I've got a friend who gaps every plug he sells to individuals in his store himself before they leave the store so that they are gaped right to begin with.
I've had this same problem on 235 and 216 Chevy engines. Just cleaning of a lot of dirt and grease build up around the base of the distributor and vacuum advance has magically made engines run that were getting no spark at all. It must have something to do with a grounding issue. I had one 1954 235 that I ended up drilling a hole in the distributor and mounting a ground wire down to the block. If I took the ground wire loose the car would run like crap or not at all.
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