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Posted By Discussion Topic: ing coil question -- page: 1 2     pauls39coupe 09-06-2016 @ 9:04 AM reply profile send p.m. Member Posts: 205 Joined: Jul 2014 Do what Tom says, as most drivability problems are electrically related. However your problem occurring in 1st gear leads me to believe you may have fuel issues. Your float level may be set too low to keep the jets covered, you may have a restriction in the line or the fuel pump may be headed south TomO 09-06-2016 @ 8:27 AM reply profile send p.m. Senior Posts: 7253 Joined: Oct 2009 The lower voltage reading is for a car that has an external ballast resister. You should see battery voltage at the input of the coil when the engine is not running and around 7 volts when the engine is above idle. Check your condenser for a solid mounting, so it has a good ground. Check the wire from the coil to the points inside the distributor, the insulation may be bad causing a short when the advance mechanism moves the mounting plate for the points. Check the point tension for 17 - 20 ounces to open them. Check the dwell at all rpms, it should not vary. If it does check the distributor bushings. Do a cylinder balance test at 1,000 rpms to find out if it is just one or two cylinders that are not firing all of the time. Tom village grande 09-05-2016 @ 4:19 PM reply profile send p.m. Member Posts: 43 Joined: Aug 2016 40coupe--plug wires are NAPA 700171 Tomo--strong spark, no problem starting or idling trjerd8--using Autolite 216 plugs car actually runs fine but noticeable miss when cruising at a steady speed. If I hold it in first gear to long it starts to stumble badly. I guess I'm hung up on the coil voltage and amperage because I keep reading on other threads that the voltage should be around 4 and the amperage around 2.75 to 3 --could my readings be different because my coil uses an internal resister? I've been told I need to add a 1.5 external resister to get the voltage down at the coil input terminal. Why would I want a lower voltage at the coil input and would this increase the amperage reading. I guess in the end could any of this be the cause of my miss at a steady speed? trjford8 09-05-2016 @ 1:32 PM reply profile send p.m. Senior Posts: 4215 Joined: Oct 2009 Are you using Champion spark plugs? I've known several people with similar problems and when they changed the plugs to Autolites the problem disappeared. TomO 09-05-2016 @ 8:01 AM reply profile send p.m. Senior Posts: 7253 Joined: Oct 2009 Your coil has an internal ballast resister and adding an external one, will drop the primary voltage causing a weaker spark. The amperage of the primary circuit,while running, is determined by the coil resistance, coil inductance, condenser capacitance, point resistance, point dwell and the condition of the circuit from the ignition switch to ground. This includes the condenser ground. The time (changed by RPM) that the coil has to build the voltage will also affect the current draw. That said, the amperage is not as important as the voltage developed by the ignition system. You should see around 20,000 volts at idle and it may drop as much as 10,000 volts at higher speeds. If you are getting a weak spark, I would check the grounding circuit of the distributor and engine. Check the value of the condenser (0.21 mfd - 0.25mfd), next and use a coil tester to check the coil off of the car. Tom 40 Coupe 09-05-2016 @ 4:34 AM reply profile send p.m. Senior Posts: 1676 Joined: Oct 2009 Are the spark plug wires resistive (NAPA #700171)?? If you have an old set of wire core plug wires try them (coil wire also). village grande 09-04-2016 @ 6:48 PM reply profile send p.m. Member Posts: 43 Joined: Aug 2016 I know the symtoms sound like a condenser problem (and might still be) but I have tried 3 different condenses, the one in there now is a Napa -ECHFA66. From what I'm reading here on the other coil thread, my voltage and amperage at the coil are wrong. I have 6.2 to 7.2 volts (battery voltage) due I guess because of no external ballast resister. The amperage is 2 at idle and goes down to 1 or less with increased RPM. It looks to me like I might need an external ballast resister even though the 51 does not call for one and the coil matches exactly the shop manual spects. Does the low and lowering amperage reading with increased RPM point to a specific problem or is this normal? Thanks for any advice--------Bill pauls39coupe 09-04-2016 @ 9:55 AM reply profile send p.m. Member Posts: 205 Joined: Jul 2014 Take your condenser off and throw it as far as you can. Take a trip to the local NAPA store and pick up a new one, I believe a # IH 200 will work, but ask a good counterman. village grande 09-03-2016 @ 5:59 PM reply profile send p.m. Member Posts: 43 Joined: Aug 2016 Carcrazy----Ign wires check normal, The installed coil meets shop manual specs (secondary ohms-4100--primary ohms 1.15) The 51 8ba uses no ballast resister. So the way I understand it the voltage to the coil on the 1951 will be the same as battery voltage which is 6.2 volts. With my amp meter connected between the coil input terminal and the disconnected input terminal wire I get a reading of 2 amps with the engine running at idle and the amperage drops to 1 amp as the rpm's increase. Shop manual call's for the engine running at idle for this test. I understand the amperage should be in the 2.75 to 3 amp range. Why would I be getting this low reading and why would the the amperage drop with increased RPM. I'm using a digital multi-meter on 20 amp scale. I don't know if this is the cause of my miss or stumble at cruising speed but I need to at least get this voltage - amperage problem cleared up first. Thanks for any advice--Bill This message was edited by village grande on 9-3-16 @ 6:04 PM carcrazy 08-26-2016 @ 8:08 PM reply profile send p.m. Senior Posts: 1659 Joined: Oct 2009 Since your car misses under load, I suspect that one or more of your resistance core spark plug wires is breaking down after it heats up. You can check the resistance of the suspect wire when it is cold and when it is hot. I have had resistance core wires that checked OK when cold but went to infinite resistance when hot. If you find that the wires have high resistance, the best thing is to replace the entire set with metal core spark plug wires as originally used by Ford. They are available from most of the early Ford vendors.

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