Re: KPack's 1954 Panama
Posted by HH56 On 2020/11/18 16:22:49
You might temporarily try a ground wire on the fuel sender itself by stripping insulation off the wire end and placing the copper directly on the sender flange letting the retaining ring press it against the sender when tightened. That should eliminate any possibility of paint causing a problem. If that settles the gauge down then either clean paint more thoroughly or figure a more permanent connection to the fuel sender. Perhaps a small hole directly in the sender flange with a sheetmetal screw holding a wire having a crimped on ring terminal.
You are correct in that the output of the instrument regulator is pulsing to give an average output of 5v. The pulsing is the main reason ordinary voltmeters will usually not provide an accurate reading. Basically the device is a bimetal strip with a heating coil wrapped around it. The way the heater is in the circuit means the regulator does need to be grounded so make sure that is happening. Current flows thru the gauges and regulator causing the heater to make the bimetal open a contact. When voltage and current flow to the gauges stop the heater cools and contact closes to repeat the cycle. Rate or frequency of the contact action depends on the total amount of current flow required by the instruments and sender resistances.
On the mechanical oil pressure gauge, obviously the easiest solution would be to add a 1/8 NPT tee and close nipples to the sender tee on the bottom port and take the output from there. A much neater solution would be to use one of the rear plugs along the main longitudinal gallery that runs the length of the block on the passenger side just above the oil pump. There is a 1/8 plug which can be removed that is positioned at every main bearing location. Remove a plug and use the needed fittings to plumb the gauge in that port. Hide the excess tubing at the rear of the engine.
Note: The plugs must have had some sort of thread sealant at the factory because sometimes they can be a bit hard to remove. If you do use a passenger side port, because of the proximity of the exhaust pipe and manifold I would also suggest buying one of the optional copper tubing kits to plumb the gauge rather than use the nylon tubing that comes with some gauges.
Here is the output of a 12v instrument regulator. 6v works the same way but with half as much voltage the waveforms are usually longer and less frequent.
Attach file:
(44.64 KB)
You are correct in that the output of the instrument regulator is pulsing to give an average output of 5v. The pulsing is the main reason ordinary voltmeters will usually not provide an accurate reading. Basically the device is a bimetal strip with a heating coil wrapped around it. The way the heater is in the circuit means the regulator does need to be grounded so make sure that is happening. Current flows thru the gauges and regulator causing the heater to make the bimetal open a contact. When voltage and current flow to the gauges stop the heater cools and contact closes to repeat the cycle. Rate or frequency of the contact action depends on the total amount of current flow required by the instruments and sender resistances.
On the mechanical oil pressure gauge, obviously the easiest solution would be to add a 1/8 NPT tee and close nipples to the sender tee on the bottom port and take the output from there. A much neater solution would be to use one of the rear plugs along the main longitudinal gallery that runs the length of the block on the passenger side just above the oil pump. There is a 1/8 plug which can be removed that is positioned at every main bearing location. Remove a plug and use the needed fittings to plumb the gauge in that port. Hide the excess tubing at the rear of the engine.
Note: The plugs must have had some sort of thread sealant at the factory because sometimes they can be a bit hard to remove. If you do use a passenger side port, because of the proximity of the exhaust pipe and manifold I would also suggest buying one of the optional copper tubing kits to plumb the gauge rather than use the nylon tubing that comes with some gauges.
Here is the output of a 12v instrument regulator. 6v works the same way but with half as much voltage the waveforms are usually longer and less frequent.
Attach file:
(44.64 KB)
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