351W oil pressure

[DAVID GAGNARD]

I do agree that it doesn't seem right that someone would set up a high perfmance engine, a street engine that is, with loose bearings.

It all depends on the way the engine will be used, this is usually decided bewteen the owner and engine builder.......

daily driver cars will have a certain bearing clearance,basically the same amount you would find in any production engine....

High performance engines that will see track duty usually have a "little" more clearance and I mean a little more, as in a thousandth or less......this promotes oil flow and the more oil flowing over the bearings,the more they are lubricated and produce less friction and less heat will be generated....a by product is a little less oil pressure....

There is a big difference in oil pressure and oil flow, more oil pressure does not mean more oil flow....

I would prefer oil flow and a lower oil pressure than high oil pressure and less oil flow in a motor......

Also, oil temp has a big impact on oil pressure.....my 65 Fastback (351-W) using 15/40 conventional oil,oil pressure is 60 psi on start-up with cold oil at 900 rpm idle, once the oil is up to 180 degress, my idle oil pressure is around 35 psi, on track, I've come in from a 15 minute run with the oil temp in the 200 to 220 range, at idle rpm,oil pressure is from 25 psi to 30 psi........this engine has near 30,000 hard miles on it right now........

BTW: NHRA Pro Stock cars have been know to run as little as 10psi of oil pressure at speed, of course they only run for 6 seconds at a time at speed......

I have a 351W with 6000 miles on it and over the last year or so the oil pressure has been slowly dropping after a long run (40-50 miles). On short runs (15 miles) it seems ok, the engine is at temp (185) in both cases. Originally it was around 55 at 2500rpm and 30 at idle (850rpm). It is now at 45 and 18. I pulled the oil filter, cut it open (what a pain) and found some tiny metal flakes in it, about 1-2 per pleat in the paper filter

I'm guessing wear from the bearing is causing the lower oil pressure since you have found metal flakes in the oil filter,1-2 per pleat is a lot to me anyway.... I don't think I've ever seen that many in an oil filter from a "good" engine.......

David