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deano
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-- 04-30-2010 @ 9:50 AM
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Hi everyone,
I'm over in the UK and have a 91a Deluxe we're having problems with. There isn't a ture pattern, but mainly when the engine is hot. It will suddenly start miss-firing and running really rough. It can sometimes be a complete pain to start when hot as well.
So far I've changed plugs, leads, rotor arm, points, and finally the coil. These were all for new items, not used.
Our main problem is there isn't anyone local who's ever seen a flathead V8 before so I'm getting really stuck.
Any help/advice would be gratefully received.
Cheers
Dean
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ford38v8
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-- 04-30-2010 @ 10:40 AM
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Dean, it sounds like your problem is the coil itself, even though you've replaced it. Coils age on the shelf just as they do in a car, so the answer is not a new coil, but a rebuilt coil using modern materials. Get hold of Skip Haney in Florida USA. He'll rebuild your coil, so that a hot start is just as reliable as a cold start.
http://www.fordcollector.com/
For people who have seen a few flatheads before, contact Chris Sanders in Upminster, Essex. Phone # 01708 222729. He'll bring you into our Regional Group #127. The RG also has it's own website:
http://www.earlyfordv8.co.uk/
Alan
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supereal
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-- 04-30-2010 @ 11:25 AM
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I agree with Alan that a hot coil is the usual cause of that problem. You can place a bag of ice on the coil to see if the symptoms lessen or disappear. You didn't mention changing the condenser, and that can also be a cause. Fords developed a reputation for "vapor lock" years ago, when quite often a failing coil was the culprit. Any old Ford coils that have not been rebuilt are almost sure to show those symptoms. We have a box full of them, and none are usable. Also, check to see that your fuel lines are not close to, or touching any part of the exhaust system, as it will cause genuine "vapor lock" so the fuel pump will lose efficiency when hot. The pump, itself, should also be checked for pressure and volume.
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TomO
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-- 04-30-2010 @ 5:45 PM
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Check the spark when the engine is at operating temperature by holding one of the wires near a head stud. You should have a nice blue spark that makes a sharp cracking sound. The spark should be at least 1/4 inch long. The rebuilt coils deliver a 1/2 inch long spark.
A common problem with both NOS and aftermarket condensers is a cold solder joint on the grounding tab. This will also cause the miss when warm.
Tom
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deano
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-- 05-05-2010 @ 3:08 AM
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Thanks all for the advice 
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deano
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-- 05-10-2010 @ 6:47 AM
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Okay had a play with the car at the weekend, and I had some more "interesting" things happen. I've rig up adaptor plate and a new remote 6v coil & condenser to help diag. When cold, starts on the button, has never run so good. but....
When the vehicle has been running and everything is warmed up, with the ignition is switched on, I get 6v coming out of the points, but when I hit the starter button and turn the engine over, the meter only pulses around the 4v mark!!
I'm guessing I've got some point robbing going on...
Anyone had this before??
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TomO
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-- 05-10-2010 @ 7:07 AM
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When the points close, current flows in the circuit and the ignition resistor drops the voltage to the coil. This helps prolong point life.
In other words, this is normal operation.
Tom
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deano
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-- 05-10-2010 @ 8:36 AM
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okay so that means the points are working all okay, I have continuity from the coil to the rotor arm, I've tried 4 condensers, new plugs & leads, fuel is getting to and out of the carb.... getting a bit lost now. Its always fine when cold, just doesn't want to start when hot 
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ford38v8
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-- 05-10-2010 @ 5:32 PM
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Deano, I'll repeat my first advice, that coils go bad on the shelf as well as on the car. A new coil is not necessarily a good coil, whereas a newly rebuilt coil is guaranteed good.
Your latest post gives me an idea, also. What is the condition of your battery and charging system? Do you have to put it on charge after a day's run? A low battery and/or poor charging system will produce those symptoms every day and twice on Sunday.
Were you able to get hold of Chris Sanders in Upminster, Essex? He and his gang can get the jinx off your car.
Alan
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ford38v8
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-- 05-10-2010 @ 5:32 PM
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Deano, I'll repeat my first advice, that coils go bad on the shelf as well as on the car. A new coil is not necessarily a good coil, whereas a newly rebuilt coil is guaranteed good.
Your latest post gives me an idea, also. What is the condition of your battery and charging system? Do you have to put it on charge after a day's run? A low battery and/or poor charging system will produce those symptoms every day and twice on Sunday.
Were you able to get hold of Chris Sanders in Upminster, Essex? He and his gang can get the jinx off your car.
Alan
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TomO
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-- 05-11-2010 @ 7:49 AM
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Deano,
Your original post stated the the engine misfire and runs rough when warm. This led us to believe that you had a spark problem. You could also have a fuel problem with the hard starting.
You need to check the spark when the engine is at operating temperature to eliminate the possibility of a failing coil or condenser.
If you have good spark, it should run and idle fine at operating temperature.
Hard starting when warm, could be due to weak spark, weak battery, flooding (too much gas) or fuel starvation (too little gas).
Tom
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