oil pressure S/W

[kg993]

Can someone recomend a good quality oil pressure switch for a 48 FL? The tiawain ones seem to mostly need more pressure at idle.

Kerry

[T. Cotten]

Kerry!

I made up a pressure-tester, and read the pressures needed to open all of the switches I had in inventory.

None approached the 4psi range;
The best were one or two of Dixie's imports at ~7 psi, although no two were alike, and some reached 11 psi.

The absolute worst were Accel's, which were either nearly 15 psi, or dead right out of the box.

'Made in USA' means nothing anymore.

....Cotten

[cdndewey]

What kind of pressures are we looking for to put out the light?

[T. Cotten]

What kind of pressures are we looking for to put out the light?

OEM switches opened at three or four pounds at most.

....Cotten

[kg993]

Well that's good-or maybe bad to hear. Had the same problem with my 65 but I guess I got lucky and the second import switch works perfect. Maybe order a dozen and test and cull out the bad. I have a nice test guage but I believe it's intended for air. Would air be accurate and heat to simulate actual conditions?
Kerry

[T. Cotten]

Well that's good-or maybe bad to hear. Had the same problem with my 65 but I guess I got lucky and the second import switch works perfect. Maybe order a dozen and test and cull out the bad. I have a nice test guage but I believe it's intended for air. Would air be accurate and heat to simulate actual conditions?
Kerry

Kerry!

I confess that I ignored the heat variable.

.....Cotten

[upsrod]

The original Stewart Warner switch used late 63 through the 80's is easy to find. The 58 to early 63 AC switch is very hard to find in working order. The AC switch
has 3 break stamped on the under side. I would guess that means it takes 3 psi to open it. My AC switch, which is NOS, flickers at idle when the oil is hot.

[40 Nuck]

Possibly ignorant question ... can the OEM oil pressure switch be fixed/rebuilt? If so, is it an easy home garage fix, or is there someone trusted to do it.

[len dowe]

Possibly ignorant question ... can the OEM oil pressure switch be fixed/rebuilt? If so, is it an easy home garage fix, or is there someone trusted to do it.

I second that as i have an oem one without the side screw hole and it weeps oil out of the little breather hole. Wondering if the diaphram? contact is broke or tore.

[kg993]

I think the insulator is roll crimped in place. I'll have to go look at one now to see.

[Steve Little]

Hi. The following information is not to discredit the readings that Cotton determined, but may help answer Kerry's question, for his future efforts of determining pressure readings and settings.

This is the field of an Instrument Fitter (which is a Australian and US term) or Instrument Mechanic (Canadian term) for a qualified tradesman in the field of *gauges and instrumentation.

Years ago,I used to race a top fuel (nitro) Harley.
We had a guy on the team who was a qualified "Instrument Fitter" and he used to set the "low and high speed) valves on the Hilborn fuel injection system of the bike.*
These were critical pressure settings that determined the performance of the engine. A couple of psi can make the difference between a winning grin.......or not.

The setup he used at the track, was a hand operated pressure pump that was filled with diesel and connected to a 12 inch diameter pressure gauge.*

He used diesel in the hand pump because it has a flow characteristic like nitro, but doesn't explode quite like the other bad tempered fuel.
This particular gauge that he was using, was worth $4000 and was regularly calibrated in a temperature controlled room at the government facility that he worked at... and who probably thought they still owned the gauge.
The gauge was 12 inch diameter to help in accurate readings and settings. The bigger the gauge, the slower the needle moves, the more accurate the reading

I remember him saying that you can't use air to set a oil valve, or*oil to set a air valve.*
The medium used to set a valve, had to have the same characteristic as the liquid, gas or air that was going to pass through it, in order to get a accurate reading.

I know!!!! a little long winded!!!! But i,m still working on my on my short answers.

[vph-d]

I've had good luck with the later Evo style oil switch. One is on an S&S oil pump Pan, the other is on a cast iron pump Pan. It doesn't look real correct, but it works.
VPH-D

[c.o.]

Don't shorten up your answers too much Steve.... :D

[T. Cotten]

Steve!

Can we really consider sending units to be valves?
It would not be hard to put a few drops of oil in its opening.

My gauge isn't a foot in diameter, however the half-pound graduations are far apart.
(attached)

Folks can get adequate readings from acetylene torch regulator gauges, etc., I'm certain.
The problem remains finding quality units to test!

....Cotten

[Peter Cooke]

Hi guys,
I work in the Naval shipbuilding industry and the day after reading all the responses above I was asked to go and witness some High & Low pressure air relief valve testing.
As our ships are being built to meet SOLAS (Safety of Life at Sea) requirements everything must be witnessed, approved and certified by an appropriate company such as Lloyds of London or the American Bureau of shipping etc, etc.
The relief valves had been removed from the air systems and were being bench tested using a hydraulic set up. I asked the Lloyds rep if they had any concerns re testing an air relief valve with oil. His response was that the SOLAS rules state that since it is only relief valve and not a valve in a system that has flow though it then oil is fine as pressure is pressure regardless of how you apply it. PSI using oil is identical to PSI using air.
This theory could apply to an oil pressure switch also as all your really doing is applying enough PSI to make the switch 'switch' and turn the light out. It's not a flow valve in a system or similar.

Just a thought.