actually this has happened to my 305 motor and i though no big deal but you got to be carful the cam shafts are soft and i guess it wasn't enough oil and i rolled a lob off of my cam.....and me not knowing exactly what went on i went and got a junkyard motor and just dropped it in. When i pulled the old motor apart i found it was just a camshaft.....but you know what my junkyard dog has lasted over 50k miles now and i only payed 300 bucks for it and i haven't had to do anything to it but replace the waterpump...and swap my quadra junk to it...

 

i already got a cam picked out for the rebuild neway
anything else this could be ive heard head gasket but i feel like the car would run diffrent if it was that it still runs perfectey fine

 

ok finally had a day off.
so for the record
If your oil pressure is dropping to 0 after the engine heats up to temp and only goes back up when you rev.....
change the oil pressure sensor first. $30 at auto zone.
did it today would ve been a 15 min job if not for not having the right size wrench (27mm) so we used channel locks. save your self the trouble and pick up the right socket (very deep should say oil pressure sensor on it) atthe parts store (5.99)while your there and buy some oil anda new filter cause your gonna change your oil whether you like it or not.its right above your oil filter pulling it was easy once we fit the locks on it but it is a weirdangle and as always laying on your back wrenchingabove tends to wear out your arms. make sure your twisting the part with the hex not the metal tube with vice grips since the tube will spin with out un-threading it (found this out the hard way). pretty simple.
oil pressure reads 30 at cold idle then goes up to about 40 tops when driving hot (reving). i also put in some thicker oil and a 1/2 quart of lucasoil stabilizer. drove around runs great. now i can drive it this summer and build a 350 in the garage. whoot

Disclaimer: im not saying this will fix all low or flat line oil pressure problems. but its the cheapest easiest possible solution. but it worked in my case and it seems to be a problem with our engine so i hope this is helpful but if your pressure is still low or 0 after trying this dont go driving around and then be pissed at me when your shxt seizes up. good luck.

 

I thought I would mention I also had the oil pressure gauge problem. I replaced the sending unit today, took about 15 minutes. Works great now, no drop on the gauge at all. My sending unit had sprung a leak and was drippin oil so if you see your sending unit covered in oil, it might be a good sign that the unit is bad.

 

The oil pressure gauge on my 91 would be pegged at 60 and go down slightly after the engine warmed up. I just replaced the sending unit today, now pressure reads 30 at hot idle! But my tach reads double, my volt gauge shows a discharge even though my system is putting out at least 14v, and once in a while my speedo goes dead (but it hasn't in a while...knock on wood). These factory gauges either SUCK by nature, or I have a gremlin hiding somewhere!