Tried bypassing the ignition switch. Nope. And it's a vintage switch from a '54 Chevy pickup as is the headlight switch. The wiring harness is good and it's not a rats nest. You are right. My attention to detail is good. I'm thinking now it might be the high voltage wire from the coil to distributor. It was moved around a bit during the takeout and reassembly of engine/trans so maybe there's a break internal to it. Will try replacing that tonight if I get home in time to catch the parts store before they close. The more I think about it, the more I think it could be the coil wire or the rotor/cap, but I'm leaning now towards the coil wire. It's regular supression carbon based wire, but it is new two years ago, although I know they don't like to be handled a lot. Still, it SHOULDN'T be the high voltage coil wire but maybe... Andy
Should get easier to fix now that it is staying broken more. Break it down by first putting test light on positive side of coil with key on. Got power? Great, now put the clamp of the test light on the negative side of the coil and the probe end to ground. Crank engine, should see a pulse/surge in the test light. If you do, the points are working. Points ok but still no spark? Stick a piece of wire in the top of the coil and hold the other end close to a ground and crank. If you have spark there but not out the cap terminal that goes to a spark plug then you have an open coil wire, rotor or cap. You can check continuity on those with an ohm meter. For test purpose you can shove any piece of wire in place for a coil wire. Had a bad rotor one time act similar, broke down under heat at first and got worse as time went on. Had an open between the inside metal strip and the tip. Hope this back to basics approach helps. Matt
Got it! Thanks Matt (Matter) for the test light suggestions. It was the key to isolating the problem. Hooked up the test light to (-) side of coil and cranked engine. Light flickered and engine fired BRIEFLY and died indicating points operational briefly. Cranked again after it died and no flickering of test light so points no longer firing and engine would not start. I figured problem was between negative of coil and points. Removed dizzy from engine and hooked up meter to where negative lead from coil bolts to dizzy and other probe to spring loaded pin that makes contact with breaker plate. Continuity good to pin but not to points. Turns out the pin was not making strong enough contact to breaker plate after all. Removed pin assembly and indeed it was barely making contact (maybe not even). I re-shaped the pin and filed down the flange of the pin assembly so pin would make better contact. Reassembled dizzy and installed on engine. Fired right up. Took for a quick spin up my long driveway and nailed it. No more breaking up under heavy throttle. Running strong. Pics to follow tomorrow. Thanks to everyone for the help. It was all greatly appreciated. Now to adjust carbs to stop from running too rich and on to the exhaust shop to complete exhaust installation. Andy
Glad to have helped, one of the first mechanic shops I worked in nearly 40 years ago the owner told me "never overlook the obvious". It was great advice, but I still often do, then I remind myself to take a moment and then go back to the basics. For future reference that test will work with most electronic ignition also. Has to have the pulse to break coil circuit which forces the coil to spark. The weak spark is why it ran crappy at heavy throttle, enough spark to burn a weak load but heavy throttle becomes too much for the quality of spark that was available. Matt
I'm happy it runs! And it wonderful to get feetback. How about the fuel leak at the non-starting incidents?
This must be why the guys in the early days of racing needed hotter spark as the more carbs and fuel they were started to dump in the motor the spark wasent hot enough so they started going with duel coils and aircraft points. This was a good thread. Learned something new from it that's for sure. I really liked matters way of the coil test. Glad to see she running. I was figuring on it being a fuel problem since you said everything was new on the coil wires plugs. Ect ect... Side. Good job now post some pictures of your hotrod so we all can see her.
Here's a little follow up. Number one son was over this morning to do an oil change on his daily. He was asking about how I fixed the problem so I took him to the workshop and was explaining the problem while showing him on a core crab dizzy I had on the bench. I removed the spring loaded pin assembly to show him the pin and I pulled on it a little and the spring and pin slid out of the housing. I had an "ah-ha" moment realizing I did not need to re-shape the pin on my dizzy or file the flange down so the assembly would travel further into the housing. All I really needed to do was to remove the pin and spring and stretch the spring a little so the pin would travel just a little more out of the assembly. I will remove dizzy from car (again) and do that tonight and post detailed pictures tomorrow along with a picture of the car as it currently sits. The kid is really sharp. As I was explaining the problem he asked, "why don't you just adjust it so the pin comes out further?" I was wondering why on Earth Henry would design that pin so it could not be adjusted and then I pulled on the pin and it slid out of the housing. So it was designed to be adjustable after all. I could have sworn I tried to pull that pin out on the dizzy in the car. Maybe that one is stuck and that being the cause of the problem after all. I will check on that tonight. Andy
I've had those type of symptoms from bad distributor caps and rotor arms. Glad you fixed it, I also had one where the spring pin had lost it's spring. Once you get the holleys dialled in, they're great carbs. Mart.
Pretty much how it works, but dual coils are generally used as a redundant system in case one goes bad. Very important on fuel cars and airplanes. The other application is on a dual plug system where two plugs are in one cylinder which is not to fire a strong mixture but to have a more even and consistent burn usually caused by in-efficient combustion chambers. That will usually allow a higher compression ratio per octane blah blah blah... sorry, my mind wanders. The funny thing about an ignition coil is it will only create the spark needed to complete the circuit when the secondary part of the coil collapses (jump the gap). Therefore, any more voltage than required to ignite the mixture is just wa$te. When I was a kid everyone had to get the new screaming yellow Accel Super Coil. Rated at 40,000 volts we all knew it was going to make some power and the bright yellow 4" square finned aluminum body sure looked the part. Didn't help a bit in the power department as we all had cars that didn't require more than the 10,000 or so volts available with the stock coil. Here is helpful tip next time you get a fouled plug that will show this, determine what plug is fouled by pulling the plug wire while the engine is running, then put the plug wire back on the plug but not all the way. Keep it back an eighth inch or so from being all the way on, play with the distance a bit and the fouled plug will start to ignite eventually firing enough to plug the wire all the way on. If it is real bad leave it slipped back to where it keeps firing until you can get somewhere to replace the bad plug. The reason this works, (and it absolutely does) is it forces the coil to increase voltage to the dead plug because it has to increase output to complete it's circuit. And that is why hard to ignite mixtures require a coil or ignition system with increased voltage potential. Matt
Andy, Great job tracking down your drivability issue. This was a post that can help others in search of their problems or at least help eliminate possible issues. Post some pics when you have time. As for the power valves, what was the issue, blown? leaking at the gasket? Cliff Ramsdell
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