Thread: 302 Stroker??

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overpost sorry

What I don't understand is how this "frequency feedback" travels without a complete loop. At 75mph your fan is not needed, and the thermostat/controller would be open, eliminating the path for 12v power to the fan motor. The fan is freewheeling, but the path back to the electrical system is blocked by an open switch, either a physical contact or an electronic switch in a controller. How does this feedback get to the other components if the fan is OFF?

Roger I agree with you, if the fan relay is open there is no feedback/generator effect, only if the relay is still closed could the effect be present.

Usually, analog circuits are less sensitive to the gremlins that effect digital circuits, and I agree with you again that his gauges being analog (not digital) chances of this effect causing his problem are slim.

General rule of electronics is to control the hot wire not the ground.

It works either way, but sometimes it can preclude problems.

If the fan is really injecting AC into the system, then I'd want to totally isolate it: use a double pole relay and cut ground AND hot. AND if the thermostat switch is too low, then the fan will be on at speed, whether It's helping or not.

Originally Posted by firebird77clone

If the fan is really injecting AC into the system, then I'd want to totally isolate it: use a double pole relay and cut ground AND hot. AND if the thermostat switch is too low, then the fan will be on at speed, whether It's helping or not.

One of my thoughts for testing if it was even related to the fans, was to ground the fans and let them run, take a spin down the highway and see what happens with them running. This should easily prove if they are even a culprit!

I'm slow, but I do get to the finish line eventually..

Just thought of this: if you run it to high rpm in first, and it doesn't occur, then you can rule out the alternator

Originally Posted by firebird77clone

I Just thought of this: if you run it to high rpm in first, and it doesn't occur, then you can rule out the alternator

I guess that would hold true.. But the aggravating part is it's intermittant. I took it out between rainfalls last night and ran down the same stretch of highway and it wouldn't react to any speed even to 80.

So perhaps something is / was loose and shaking?? or?? idk..

So I think I'll just go through and verify connections and make sure they are secure & clean..

Could be temperature related. If the temp switch cuts out, the relay opens, and the fan looses ground, free wheels , generating a floating voltage

Originally Posted by firebird77clone

Could be temperature related. If the temp switch cuts out, the relay opens, and the fan looses ground, free wheels , generating a floating voltage

With the loss of the ground the circuit is open, even if the fan could act as a generator the output would go no where the circuit is open.

Originally Posted by pepi

With the loss of the ground the circuit is open, even if the fan could act as a generator the output would go no where the circuit is open.

No, a stray voltage can still be induced and backfed up the positive side, essentially out of phase even tho' it's not AC current. The fans could potentially pulse feed but I don't fully believe it's happening, This same basic effect happens when you run spark plug wires parrallel to each other. It was so prominent that on ford v8's of the 50's, 60's and 70's one wire on each side of the motor was intentionally placed wrong in the wire seperator to break the voltage spike and false fire the plug!

I was searching if someone here had this experience as I have read about it on one of the forums I frequent.

Originally Posted by 34_40

No, a stray voltage can still be induced and backfed up the positive side, essentially out of phase even tho' it's not AC current. The fans could potentially pulse feed but I don't fully believe it's happening, This same basic effect happens when you run spark plug wires parrallel to each other. It was so prominent that on ford v8's of the 50's, 60's and 70's one wire on each side of the motor was intentionally placed wrong in the wire seperator to break the voltage spike and false fire the plug!

I was searching if someone here had this experience as I have read about it on one of the forums I frequent.

Well, not to nit pick, but first of all electrons need a path pos too neg. or neg. too pos, no path no go, feed back does not skip over open air. The interruption to ground of the coil that energizes the relay contact opens, no path. Second the spark plug example you bring forth is a totally different circumstance. The plug wire has a high voltage field external to the wire, it rises and collapses as the plug fires, that induces voltage into a wire close to it, this is known as counter EMF all high voltage has that capability.

As to this fan thing being a viable voltage generator ........ Unlikely, it is not going to spin fast enough from the get go. Other items are in play such as . Most circuits in your car are wired in parallel so even if the fan became a power source it would not add voltage. One more and I am all done with this, the fan generator will need to have a greater potential. Greater voltage then the circuit it is wired on, if not it will be ignored by the circuit, the most it could do if it were electrically in the circuit would be a load.

Such as it is, you are or were looking for an intermittent ground. If the car was up on jacks, just sitting the motor out less weight the frame and body sit differently. Maybe it opened up a space,, that caught a little rust, now that you have taken the car out and spun it up a few times, everything in place it has fixed itself. That would not be the first time an electrical circuit got quirky in a machine or car that has sat unused, airplane systems are much worse when the are not flown regularly.

Or perhaps (speed) something was shaking a connector loose enough to cause the headache!?!?! Or perhaps I'll never know!?!?! Sigh.. LOL..

I was reading thru this again and noticed that you said that you "controlled the ground" with the relay. Did you mean that you run constant voltage to the motor and use the relay to close a grounding circuit of the fan motor?


The reason I ask that specificly is because most use the relay to break/make the voltage to the fan motor

Originally Posted by jerry clayton

I was reading thru this again and noticed that you said that you "controlled the ground" with the relay. Did you mean that you run constant voltage to the motor and use the relay to close a grounding circuit of the fan motor?

The reason I ask that specificly is because most use the relay to break/make the voltage to the fan motor

Yes, that is correct Jerry. For the fans and also the wiper motor. I copied a Chevrolet Corvette and control the ground circuit to make / break the circuit. A friend has a vette that was having some electrical gremlins, he asked if I could help sort through them, and I learned that for the wipers at least they were controling the ground circuit to run them. I don't remember the year but maybe 67 or 68?? This was the year the cowl had a door over the wipers which had to open first then the wipers would start.

ANyhow, I copied it and carried it a step further. And no.. I am not a "conventional" sort of person.. always testing and trying things "just because I can"

Geez, all this fancy electronics, and I still have a cable drive Moroso tach on the shelf!!!!!! (Saving it for just the right project, I guess)....