Not to worry.   It's normal in hot summer weather.

   Fortunately, at idle there is almost no load
   on the bearings and very little pressure is needed
   to keep them happy.

What is your idle speed? It is normal to have VERY low oil pressure at
idle, but the light should not come on. It is an indication of worn
bearings allowing oil to escape too easily. The warning light also comes
on at a very low pressure, personally I would adjust the idle speed a
little higher to "hide" this problem, and ensure proper lubrication,
until I have time to rebuild the engine.

You could also try thicker oil, like 20W50 or straight 30W.
Stay away from ultra cheap oils, and synthetics. Synthetics have low
viscosity, they don't help with pressure in your case.

Jan

"bob tonucci" wrote in message...

The switch will open between 2.1 and 6.4 psi.  Your pressure seems low,
across the board, although it does depend on what type of oil you are using.

The engine oil is 5-30, and was just rebuilt by me and all the bearings to
the crank and rods were new and new crank, they were also plastic gage for
fit., I suspect that the low oil pressure may be due to a weak pressure
regulator spring or the JC Whittney oil pump, or the 5-30 oil. I will try
the 20-50 first. What should be the regulator spring length unloaded.
Thanks for your help.