Well my friend's been modding his '67 mustang and anyway he took out the old 289 and freshened it up and then built it up with a bunch of nice performance parts....10.7:1 compression, edelbrock performer rpm heads, edelbrock rpm cam (somewhere around 230 duration in the .500+ range), edelbrock manifold, etc etc. Anyway we finally dropped it in and we straightened out everything out and went to fire it up yesterday, and well, it didn't. no spark. Well after troubleshooting all of yesterday and this morning, we finally just gave up with his $500 msd ignition system and we threw the old coil and distributor back on and it started right up. Now here's the problem. We were running it for the 20 minute break-in period for the cam. During the time he was building up the motor, we installed a bunch of autometer guages and the oil pressure guage only reads about 17 psi. Another thing is that the motor shut off twice during this period: once when he was fiddling with the timing, he retarded way too much and the other time the voltage got too low (alternator isn't working right). And during this time he still had the timing retarded way too much and the headers got red-hot (the base timing was okay but he left the vacuum advance unconnnected while the motor was idling at about 2000-2500 rpm ). Obviously, this is NOT good at all for the motor considering we had to restart it two times, the oil pressure was supposedly low, and the motor got hot. :sad: The thing was so freaking loud on open headers i wouldn't be able to hear any rod knock or something along that order. I don't know, is this motor trashed or what? Could that guage be inaccurate? There's a plastic line i guess that goes all the way from the passage in the block to the guage and it had some oil in it but there was air in it too.

 

Air in the gauge oil line won't make any real difference. The gauge reading should still be very close.

Even at 17 PSIG, the oil pressure should be adequate at 2,500 RPM as long as there was no heavy load placed on the engine, and there shouldn't be if you were breaking it in correctly.
Retarding the timing would have made the exhaust really hot, but shouldn't have caused any real damage. Shutting off the engine during break in is not that much of a problem. I've interrupted a break in because of overheating, leaks, and laziness, and never had a problem.

Your engine should not have been damaged by anything you described, unless there's something else you're not mentioning. I would check into the oil pressure issue before driving the car too much, but the low pressure may have been from hot oil and the cam break in lube clogging the filter. Watch the oil pressure more closely after changing the break in oil and see what happens.

 

Couldn't have said it better myself...

The air is compressible, but will still have the same pressure as the oil, so the reading should be accurate.

Don't worry about the apparently low oil pressure until it is broken in and you have a good oil filter and oil in it.

 

i'd change oil and filter and screw a mechanical gauge in thje block somewhere. i just changed oil in new engine i built 2 days ago, the oil was black after 30 minutes. i don't know where all that trash comes from. must be the moly lube turns it black like that.