Which Oil Pressure Gauge?

Jay Ess

Jay Ess

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Am I correct in presuming that as the Model A engine has so little oil pressure to begin with, (in comparison to later tech.) that the narrower range of 0 -10 lbs would be better to indicate or notice whatever small changes take place? How about reliability of one over the other? Thanks in advance. js
 
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Yes, if your engine is stock and the oiling system has not been modified, you would be better off with the lower reading scale as the stock engine only develops about 3 PSI max when warmed up.
 
I would think most who chose to run an oil pressure gauge on a stock engine would worry to much watching the gauge and not the road
 
Steve Wastler said:
I would think most who chose to run an oil pressure gauge on a stock engine would worry to much watching the gauge and not the road
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I had to have this totally re-built last year as I did not notice the oil pressure gauge until it was too late. So yes, I will be glancing over at the gauge from time to time. :)

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Jay, sorry to hear you had to have your engine rebuilt, but that is the oddest stock A engine I have ever laid eyes on.... ;)
 
Jay Ess

This is what I would do if it were my engine. Put a known good gauge on your engine during a cold start-up, and/or when you will have the highest oil pressure that your engine will produce. Observe what the maximum oil pressure that your engine produces and obtain a gauge that is within the pressure range of your engine.
I attached a data logger chart from a Certified Digital Gauge that I put on my newly rebuilt Model A engine. The only modification to my engine is that the oil pump was improved to the Model B design, undercut shaft and larger output opening. It is capable of producing around 15 psi, If I were to put a 10 psi gauge on my engine it would exceed the gauge limit by 50% and ruin the gauge. Once the gauge has been over pressurized it is no longer reliable.

Darryl in Fairbanks
 

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Years ago when I was in ground school class the instructor asked what was the most important gage on the panel. You might think it would be the airspeed or altitude but the answer was the oil pressure gage. If you loose oil pressure YOU ARE GOING TO LAND SOON weather you want to or not. Get the smaller range gage and I would get the temp gage too. Bill G
 
I would agree most engines need a pressure gauge, but a bone stock 'A' no improvements what so ever and a maximum pressure of three pounds even with a low reading gauge you will never fully enjoy driving the car A's you will be worried with even the slightest variation, which is completely normal. There is no way with all the variables a bone stock engine will always register 3 pounds.
 
I once had this 1937 REX-A-CO Oil Gauge installed. It would reach about 8 on cold start up, then down to 1 - 2 when hot.

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Never succeeded in getting the Boyce water temp gauge to work.

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So it sounds like pressure gauge might not be worth the expense. If The engine, once warm, is only running 3lbs of pressure, I don't think one would notice a change regardless of the gauge scale?
 
Horse,
Your Boyce temp gauge sounds like my body, old & tired. I have oil & temp gauges, new. Stock '29, for simplicity will pass on the oil gauge, if it sounds quiet, I can assume it has pressure.
Temp gauge is a MUST! When head was off, I mapped out a location in the L/R of head, on the side. Chief always put them there, just seems like a good place and lots of older flathead 6 cyl cars used that location. Only has to be drilled & tapped for 1/4 pipe thread, plenty of room inside water jacket. Just a thought, I wonder if some old coil brackets might be used for gauge mounts?? size?? Bill W.
 
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Jay Ess said:
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Am I correct in presuming that as the Model A engine has so little oil pressure to begin with, (in comparison to later tech.) that the narrower range of 0 -10 lbs would be better to indicate or notice whatever small changes take place? How about reliability of one over the other? Thanks in advance. js
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The Rex guague has no upper limit stop. If it is below freezing, my Rex a co gauge needle goes way past the "10" psi reading to about the "CA" letters at the bottom of the gauge. Once it warms up, it settles in the 2 to 3 psi range. Probably the upper limit stop on the APCO gauge wouldn't hurt anything if the needle hit the stop, but I don't know.
 
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