I'm continuing the process on my learn as I go setup of a 8BA flathead engine that I will be installing in my 30 Modal A Tudor. I have converted the engine to 12V negative ground and it now is on an engine stand to get it all up and running before I start my process of building the car back up. Cranking the engine and pumping fuel into the carb all seem fine but I am having trouble with spark. I had pulled one (and then another) plug to test spark while turning over the engine and I had none. I had then spotted some issues with my points gap in the distributor and made adjustments there to no avail. At that point I had decided that I was going to systematically go through each component in the ignition chain to work back to where the true issue was and make sure there were no issues in the wiring or components prior to the distributor. I pulled one of the plugs and wires and directly hooked it up to the coil output and then ran power directly to the coil terminals to test for spark but none was found on that plug/wire combo along with three others. I ran through the same process with the old 6V coil (which I think is functional but don't know for sure) and still no spark. Either what I'm doing is the wrong way to approach this (again this is my first build and I'm learning on the go from YouTube, etc., on this) or I do have a fault in my coil or every one of my plug wires, etc. The coil is a brand new 12V model with an internal resister that eliminates the need for a secondary resister. It measured 3.9 Ohms across the terminals on my voltage meter. I tried to test continuity on my plug wires but they don't register on my multimeter but I believe that is normally the case as most multimeters don't run enough current for plug wires to carry. My battery is good at 90% life and it cranks the engine strong. So for those in the know what am I doing wrong here and what could I do better? I know I have some work to do on the distributor setup but before that I would like to ensure all the other components in the electrical chain have no issues. Is my method of testing the coil and spark by directly powering it up from the battery and outputting to one plug the right way to do this or is there a better way? What is the best way of testing the continuity of spark plug wires in-lieu of a multimeter?
Possibly a bad condenser. An ohmmeter is a dirty-non-conclusive test, but one lead on the wire, one on the case, should see resistance build up.
It would be nice if you had a volt meter, but a test light would do. Check for power at the distributor side of the coil (-). If you have power there, check for power at the powered side of the points. If you don't have any power there, fix the connection between the coil and the points. If you do have power at the points, bump the engine over until the points are closed. If you still have power, there is no ground for the points and it needs to be fixed.
Did you ground the plugs to the block when testing? What type of wires are you using? What type of distributor are you using? Was this motor together and running at some point or did you assemble it?
A few things on any engine with points. or any other gas fueled piston engine with a distributor, separate coil and battery ignition. 1. Are you positive that you set the point gap correctly. Some mouthbreather will pop off and say this is a 216 Chebby distributor but a distributor is a distributor in the class i teach. Note at the blue arrow the rubbing block is exactly on the tip of one of the distributor cam lobes. thid the only place the rubbing block can be when you use a feeler gauge. note that the points are open. red arrow. That if fuck up number one when guys don't joggle the distributor cam around to get it likr that. On an 8 B A it is easy to get the wire from the condensor on the wrong side of the insulator block that goes through the distributor housing. I did that when I and my buddy decided to change the points in my 51 mercury 61 years ago. Walked a half mile from Jimmy's house to my auto shop teacher's house got laughed at then told what to go back and check. 2. the polarity on the coil has to match the rigs battery ground NO EXCEPTION. Yoy put the battery in negative ground the coil is wired minus pole to the distributor and plus side to ignition. 3. A good number of ignition switches with a start pole do not send power to the coil in start position. Those rely on the resistor bypass pole on the solenoid and the bypass wire to carry power to thr ciol when cranking. Test for power to the coil when cranking and when the key is on. 4. You do have the distributor in time with the engine and the firing order correct for an 8BA Some times we forget and wire the hot rod engine the same as the engine that we have been used to rather than correct. Been there, done that and a 283 won't start when you ron the firing order the same as an Olds 350. If you don't have a decent test light and at least a basic multimeter it is near impossible to troubleshoot without them.
Easy test that eliminates the condenser and points to see if it is the coil, Just ground the coil post that normally goes to the points and apply power, briefly, to the other post. With a plug wire in the coil tower and a plug on the wire and grounded to the engine you should see a spark every time the power is removed from the coil.
If you are using the stock distributor, Check the wire that runs under the breaker plate. They get worn and frayed and short out. The wire runs from the hot wire to the points. You can't see it under there without removing it. Common problem with this distributor and an easy fix.
Thanks for all of the suggestions. I am going to try a new set of plugs and wires and also upgrade to a new Pertronix coil. The engine had been rebuilt and “ran when pulled” but the plugs look old and the wires have aged so they could benefit from being replaced anyway. I will be double checking all my grounds as that seems like a possible culprit as well trying to get spark before addressing the distributor. Once I get past basic spark from the coil I will turn my attention to the distributor as I know I have some work to do there.
You may want to run a piece of fine sandpaper through the points to remove any oxidation. I have seen perfectly good looking points that would not work, sand off the unseen oxidation and and got spark.
Also possible to get oil on the points from the feeler gauges or fingers etc .... After setting them I always rotate the distributor til points are closed, then drag a clean white piece of paper through them to clean the oil off of them. I use white because you can see the dirt you pull off the points, when paper comes out clean you are done .... might not be any at all but you will know you cleaned them after setting then. I have had no start issue after installing new points, was surprised how much oil came off and it did start after cleaning. ..... Now I always clean them. I also vote on bad condenser, I just went through this again a few weeks ago. Installed a new condenser and it had no spark at the plugs. IIRC, if you have a really bright spark at the points it is a sign your condenser is not working. While a duller spark would be a sign your condenser is doing it's job. Over the years I've had terrible luck with modern condensers and have got 4 that were DOA straight out of the box. I had one that worked for a very short time then failed. Currently I'm using a aftermarket condenser I mounted outside of the distributor and feel more confident it will last .... is made by a H.A.M.B. member and they claim they have not had one fail yet.
Ok I am still doing something wrong here: I am trying to do a spark test to verify my coil, plug, wire, etc. is ok BEFORE testing and addressing issues related to the distributor. I have seen this test done by others and I'm trying to replicate it and either I missing something simple or the methodology of this test is bad to begin with. I have ran two test wires (10 gauge) directly from a fully charged battery to the coil. The coil is a brand new Pertronix Flame-Thrower coil (40011). Positive wire to the + terminal on the coil, negative wire to the - coil terminal. I read from my multimeter a 12.7 volt current across the coil terminals when hooked up to the battery. I pulled one of the spark plug wires from the distributor cap and verified it was correctly functioning with my multimeter. I pulled back the boot on the distributor end so I could seat the wire fully into the coil output. I tested continuity again between the coil and the end of the plug wire and everything was good. I fitted a new NHK plug gapped somewhere between .035 and .030. I ran a ground wire directly from the coils - terminal to the side of the spark plug to ground it for sure. When I tap connect this test circuit with the battery I get no spark. Again I'm trying to do a basic test of these components BEFORE moving on the the distributor as I know I probably have work to do there and I want to ensure these components in the ignition chain are good and functional so I have no doubts about them when I am diagnosing and fixing issues with the distributor and its components. Is there something that I am doing wrong specific to this test? Is this test that I am trying to do simply invalid and should I approach verifying these components a completely different way or should I just move on to a full circuit test with the distributor, etc. since everything seems to check out with the multimeter with the coil, plugs and wires individually? Again I'm going through this process my first time so there is something I am doing wrong here for sure.
If I'm looking at your connections corectly, there is no way this will work. You have to break the coil primary circuit to induce the high voltage required to make the plug spark. You need power to one of the coil primary terminals and a wire to the other that you can tap on ground (a direct conection to battery ground). You also need a separate ground going to the spark plug. It appears you have the ground side of the plug connected to the coil primary. I needs to be connected to battery ground. It appears that your connection keeps the coil primary circuit energized at all times. The purpose of the points in a point ignition system is to break the primary circuit momentarily to build high voltage in the coil secondary circuit (high tension wire coming out of the coil). In an electronic system there is a module in the distributor that basically does the same thing the points do.
You may as well wire the run stand as you would the engine in the Model A. It's not like buying extra parts: you will need a start solenoid, a ballest resister, a main on/off switch or a modern key switch with a off/ on /montary start & Accessory position. Has the engine run enough to break-in the cam? Run the engine enough to check each cylinder head temperature and set the timing and adjust the carb. I'd run at least 2 heat cycles and retorque the head bolts after the engine cools each time. Do as much as you can on the engine stand rather than leaning over the fenders. JMHO
Thanks for the suggestions. I was able to get spark on the isolated coil test. I moved on to working on the distributor and did not get spark there. I replaced the points, condenser, and rotor to ensure those were not the issue and still no spark. I am converting to 12v negative ground in the process of getting this engine up and running again and I suspect my wiring may be at fault. This diagram represents how I have it currently wired on the engine stand. Are there any issues with how I have wired things? Another possible problem (or symptom) is that my ballast resister gets very hot when powered which I suspect is due to something being incorrectly wired.
Yes, the wire going to the distributor should come off - side of the coil. It provides the ground. Remove the wire you have labeled ground. The purpose of the points in the distributor is to make and break the ground in the coil primary circuit. That ground wire would make the ballast resistor get hot with the primary circuit grounded all the time.
The starter button shows 2 wires in the diagram. The original Ford button had only the wire from the I terminal on the solenoid which went to ground ( through the dash) when button is depressed. If your button has 2 wires , one goes to I terminal and the other to a good ground.
Yep. At this point, check for voltage at the points. Should have voltage and it should spark when the points are opened and closed.
Many thanks to jaracer. I made those simple changes and the engine fired right up like a champ. One thing I did had to contend with is possible issues with the ballast resister. Initially after I made the changes there still was no spark so I went back through the wiring chain to test voltage. At the resister I had 12 volts going in but less than 5 going out. I don’t know if this is normal or a symptom of a now bad resister likely caused by my improper grounding and resulting overheating of this component. When I removed the resister from the electrical circuit and ran power directly from the switch to the coil everything worked just fine. I am currently running the Pertronix coil that has an ohm rating of 1.5 and I’m unsure if it is better to install a new resister in the circuit or not. I had read somewhere that your total ohm resistance to the coil should be closer to 4.0 which the ballast provides in conjunction with a standard coil. I also have another 12v coil that has an internal resister and thus does not require the ballast. Perhaps I should switch back to that if I do not include a ballast in the circuit.
Confirm with Pertronix what the coil requires. It should be in the paperwork with the coil or on their site. Make sure all components are matched. Ballast is probably fine. The idea is to step down the voltage as your testing shows. But again, verify what the coil requires. Too much voltage will overheat the coil and burn it out in a short amount of time.
The Jalopy Journal
