flathead quits

mech-for-cars

mech-for-cars

Junior Member
HI GUYS,I HAVE A 59AB V8 FLATHEAD IN MY 35 FORD.FRONT MOUNT CRAB DISTRIBUTOR. I CAN DRIVE APROX. 5 TO 10 MILES THEN IT QUITS RUNNING. IT ACTS LIKE WHEN YOU HAVE A BAD COIL& WHEN IT GETS HOT IT WILL START JERKING & THEN JUST SHUTS DOWN. IVE REPLACED THE COIL,POINTS, CONDENSOR EVEN THE RESISTER UNDER THE DASH. WHEN IT DOES QUIT,IF I GET OUT WITH A JUMPER AND JUST GIVE A QUICK TOUCH FROM BATTERY TO DISTRIBUTOR TERMINAL TO POINTS WIRE,IT WILL FIRE UP UNTIL NEXT TIME,ITS RUNS LONG ENOUGH TO QUIT AGAIN. STUMPED? :confused: ANY HELP WILL BE GREAT.
 
Even though you replaced the coil it could still be the problem. 99% of all original coils will quit in hot weather when they get hot, even an NOS one. The problem is the coil but whether it is the coil itself being bad needs to be checked. When you jumped the battery directly to the coil you increased the voltage to the coil which will also increase the output spark. Make sure the battery is fully charged before you start and should read 6.3 to 6.5 AT THE BATTERY. Take a good voltmeter and put it from the the ignition wire at the coil to ground. Turn the ignition switch on and read the voltage there are 2 readings you need to get. One with the points open and one with them closed. You will be able to tell if the points are open or closed by the voltage readings. Open should be very close to the 6.3 battery voltage, closed should be between 3.5 and 4.0 or maybe a little more. in the 3 volt range or below it may start but be hard and sometimes just as you leave off the starter button it will start. It will also start if you drift down a hill and let the clutch out. This is because the starter isn't robbing the voltage from the coil. Before I forget don't leave the switch on more than 2 or 3 minutes and make sure you turn it off when you are done or the coil will burn up. You can just bump the starter button while watching the meter and see when the voltage drops that's when the points are closed. I know you have low voltage to the points or a bad coil requireing more voltage when it gets hot. If it is not the coil the voltage is is being lost across a bad connection which acts like the ignition resistor. Bad ground, small battery cables, dirty or bad battery connections a dirty, worn ignition switch or one of those green or black knob battery shut off switches. The jumper proved it is one of these parts. G.M.
 
just a guess here from a newbie.....if your running an electric fuel pump, check and see how clogged the filter is that is connected to the pump. If not,,,,,good luck. I had the same symptoms a couple years back, and never knew the filter was there until i replaced everthing else but. :) CP
 
If you have 6 volts you need a .5 ohm resister.if you have a newer 1.5 with 6 volts you will only have about 3 volts across coil. 12 volts needs a 1.5 resister with a 12 volt coil.Some times the one under dash is over looked and you have one to many.My 39 had and extra one and was hard starting when hot.If you have a meter read across resister should only be 1.5 volts +or- rest across coil.
 
I see you are running the resister ,If the coil is a after market canister one run it with out the resister .Or set up a temporary wire from the switch direct to the coil .As GM said you have a voltage drop ,small cables can cause hard starting when hot .Also get the distributor set up on a fixture ,Ted
 
HI TED, DOES THE ROUND CANISTER COIL HAVE A BUILT IN RESISTER IN IT? IF SO,WILL I BURN UP MY POINTS BY NOT USING THE RESISTER UNDER THE DASH? THANKS:confused:
 
If you have a round coil you will NOT need a resister.Ford is the only one that needed a resister for 6 volt coil.After 48 no resister is needed till 12 volts in 56.
 
I spent several months replacing almost every fuel and electrical part on my 40 flathead as mine would act identical to yours after about 5 miles. It did not even have to be real hot out and it would jerk and then stop. We ruled out fuel related problems after many tests. Two flathead builders locally explained an old trick most of you know about regards the ballast resistor under the dash. I went through 2 or three new ones (use only original style like Carpenter sells) but when I put the last one on, I hot wired across it with the wires coming down to where I could easily reach and quickly flip a toggle so a full 6 volts went to the distributor. Do not worry about driving home that way as your points are not going to burn out in 10 minutes like some say. I permanently mounted this toggle under the dash as I still do not have faith in the car after so many breakdowns. I always tested the car in the area with my son following me in his truck and tow strap and we used that strap many times. Many of the NOS parts on the shelf or from swap meets are no good. Many of the repro ones from Taiwan etc. are junk. I tested all my spare coils on a tester that produces extreme heat surrounding the coil to simulate real life conditions. I carry a spare coil, distributor, condensor and ballast resistor. Hopefully this fall I will take it for a longer ride and gain faith back. I do not have to explain why my street rods get more use than the stocker. Good luck and don't give up. If the car runs on the full 6 volts, it is the ballast resistor I can bet.
 
Hi To .As George said no Resister needed .You have a voltage drop somewhere so the chances are that you will not shorten the point life any way,but that's a side issue your main concern is to get it running good .Some coils had a resister built in some had it in the wiring .(Resister wire ) Often a 12volt coil is actually a 6volt one but they don't tell you. That is its not marked ,but somewhere there will be some resistance built in A Flathead has one of the worst reputation for braking down or not starting ,more than any other car, example Mr 34s post. I know of 5 here that are not driven because of it , That's not to say these problems cannot be solved and made reliable ..I think you have two issues one is voltage drop and a heating coil .I would say it may not be the resister, but you cannot rule any thing out .I have attached a picture of one of my cars that i run a resister on the USA 6V canister coil .I did this to see if there were any adverse affects there are non to date .I am all for simple test procedures .One of my main tools is a 6ft piece of wire with two Alligator clips one on each end . By clipping this wire at various places you can rule out the circuitry behind it if the motor runs good .You should also do as GM says and clean all the connections and the Ign switch,As a test you should take a spare coil with you and when the car plays up swap it out .you could mount it near the other one and just clip it on while everything is hot .I recently worked on a car that would not start when hot ,so I jumped it direct to the starter with my 12 volt Toyota ,It fired up straight away , This indicated Voltage drop due to the starter drawing of , required current ,I put heavy cable on ,Problem solved .Try these things then come back to us or send me a personal message ,Ted



mech-for-cars said:
HI TED, DOES THE ROUND CANISTER COIL HAVE A BUILT IN RESISTER IN IT? IF SO,WILL I BURN UP MY POINTS BY NOT USING THE RESISTER UNDER THE DASH? THANKS:confused:
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My 38 with the same symptoms turned out to have a wire from switch to coil that lost enough conductivity when hot to stop the car like a bad coil, condenser or running out of gas. When it cooled off it was fine for a while. Swapped everything with no joy and finally put a jumper wire from the battery to coil and it was fine.
 
I often wonder if these problem happen when fooling with car,or this is happening afters years of running.Now my guess you are using a 12 volt coil with 6 volts.It most likly will run, but not for long.
 
When a stock Ford is modified with differant coils, switches, electric pumps etc it is hard to trouble shoot for problems. Having a differant coil was not mentioned in the inital post for help. With stock parts it is simple to find a problem as every engine is the same, problems are repetitive and can all be tested the same. These cars don't need round coils, 12 volts or electric fuel pumps they start and run great just like they are. There are problems with the stock coils due to materials used in that time period and age. Have your stock coil rebuilt and your starting problem is over for good at all outside temperatures. Skip has rebuilt over 13,000 old Ford coils and they all work and hold up good. NO ONE has ever been charged for a coil repair no matter how old it is. There have only been a few that had problems in all these years. A few have been damaged because the ignition switch was left on and in some cases with a battey charger hooked up, this really makes a melt down. In at lot of cases even the switch being left on don't damage the coil and the battery runs down first. If the points are closed the coil will get hot and may get damaged, if the points are open the coil is disconnected and there is no damage. All of this bandaid fixing is what leads to constant problems like the guy with the tow rope. If the wireing is bare and the insulation is breaking at least put in a new dash harness. The wires are all color coded and a simple diagram usually comes with a new one. Put in new 2/0 battery cables with good ends and clean all grounds where the cables contact the metal and put electical grease on the battery and ground connections. Do not use the green knob type battery shut off. I know I promoted these a number of years ago but have had problems with 3 of them, one recently where almost any load along with the coil causes a voltage drop. I run a GPS on 6 volts and it would shut down from low voltage every time I hit the brakes even with a 6 volt alternator that charges at idle. Late yesterday when I came back with the 39 I let it idle for a minute or so watching the digital volt meter below the dash and at a very slow idle it was showing 7.26 volts. After have having sluggish starter power and the GPS dropping out for several months one day after lunch there was nothing when I hit the starter. I got out and loosened the green shut off knob, retightened it and it started. I got a REAL battery disconnect, installed it and the starter spins like it has 12 volts applied and the GPS never drops out and will now continue to run even after the engine is shut of. It will however shut down when I hit the starter. Parts are not very expensive for these old Fords compared to newer cars. Fix it right the first time, it will be cheaper in the end and you will be able to drive and enjoy the car and not have the fear like the guy with the tow rope which gives advise to others?? G.M.
 
As I said get the distributor set up on a fixture .The 59AB can take a of the shelf canister coil .The resister is one item that's not often fully understood why they put it on , .The word ballast indicates to stabilise to adsorb fluctuation in current like from the generator .And to help keep the voltage low at the points ,to extend point life as Ford wanted 50,000 miles out of his Distributors Also to boost voltage while starting ,later cars had a by pass from the key.
 
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