| Tracker | -- 11-05-2012 @ 10:43 AM |
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When the kick down switch is pressed down to pass another car, the engine starts to miss and backfire. When the kickdown is released, the car goes back to normal operating mode. In park at idle, if the switch is depressed manually, it stops the engine. Can anyone tell me what to begin looking for ? The fuse is good at both ends so not sure whats happening. Thanks for your help.
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| supereal | -- 11-05-2012 @ 1:40 PM |
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The kickdown switch activated by the accelerator contains two sets of contacts. The normally closed set furnishes ground to the overdrive relay via the governor. When the pedal is full depressed, the normally open contacts ground the ignition points on the condenser side, if the overdrive is engaged thru the rail switch. This actually shuts the engine down to allow the OD to release. From your description, I'd suspect the kickdown switch contacts are not making full connection. This can be checked with an ohmeter. If you need a wiring diagram, I can post one.
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| Tracker | -- 11-05-2012 @ 5:56 PM |
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I would appreciate any help you can provide...if you would, please post the diagram. To be clear , is depressing the kick down switch while the engine is idling supposed to stop the engine altogether ? If I press it by hand and hold it , the engine stops immediately. If I press and release it goes back to normal idle. When running down the road , any attempt to make it go into passing mode causes it to back fire and would quit if held there. Thanks for your help. Tracker The kick down connections appear to be tightwith no breaks that I can see
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| supereal | -- 11-05-2012 @ 7:39 PM |
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The kickdown switch is only active if the overdrive is engaged. The governor should not allow engagement if the engine is idling, so you should not be able to stop the engine with the switch unless you are moving above the speed the governor closes. I'm sending this from my iPad, so it will scan and post the circuit diagram for you when I am back in the shop tomorrow.
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| supereal | -- 11-06-2012 @ 9:41 AM |
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I am attaching a copy of the overdrive wiring.It is important to know how the kickdown works. The downshift from overdrive to standard drive is activated by the kickdown switch under the accelerator, which has two functions. It opens the control circuit, causing the solenoid to deenergize. Because of the torque applied to the OD, it can't release until the driving torque is released. The kickdown switch grounds the ignition points, and the mechanical portion of the OD is then released. When the solenoid drops, the set of points used to ground the ignition opens, ending the interruption of the engine, which lasts only one half revolution of the crankshaft. As you report that you can short the engine out while idling by pushing the kickdown switch, it is probable that the switch inside the solenoid cover is stuck closed, or the wire is grounded. Look for the switch with the orange wire. The solenoid has two windings, one to pull, and the other to hold, operated by the blue wire. The contacts inside the solenoid case are subject to considerable current, and are known to cause problems such as you have mentioned.
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| Tracker | -- 11-07-2012 @ 7:29 AM |
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Thanks for the od wiring schematic ....its the best I have seen. Beginning today to locate the problem and will report back what I find as I'm sure others have had the same problem. Your info is always spot on SR. Thanks as always for your help and interest. Tracker
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| Tracker | -- 11-08-2012 @ 4:39 PM |
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The answer to my overdrive problem was right in front of my face all along....when the engine was re-installed the shop connected the coil wires up wrong...instead of going back to the hot ( negative side )of the coil both the distributor and kickdown wires were both connected to the positive swide of the coil. The engine did not show negative polarity but it did lack power and my guess is the coil was the culprit for the power loss. At any rate , all is now back to normal although I am still amazed at what these old flatheads will tolerate and still run. My thanks to Super Real for his help in getting this problem resolved...the drawing of the OD and the explanation how this all came together was really helpful to a novice like me.Thanks again. Regards Tracker
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| supereal | -- 11-09-2012 @ 6:53 AM |
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I'm glad you solved it. Trying to fix a problem without a diagram is like traveling in unfamiliar territory without a road map. At our shop, we spend big money on a service that provides info for all kinds and brands of vehicles. Without it, it is impossible to find and fix problems.
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