Posted by Jim L. in OR On 2012/7/4 13:53:11
Quote:
Craig wrote:
[Just to clarify this "rule of thumb." This number (10psi/1000rpm) is OK for a nominal 3.000in main bearing diameter. For a Packard V-8 with 2.500in mains, the number would be ~8.3psi/1000rpm (2.5/3.0). For example, a Pontiac 421/428/455 with 3.250in main bearings, the value is ~11psi (3.250/3.000). The early small block Chebbies had a 2.300in main journal and could get by with 7.6psi/1000rpm.
The reason for this is that the oil pressure has to overcome the centripetal force of the oil in the internal passage from the bearing surface to the centerline of the crankshaft before any oil can reach the rod bearings.
The above is probably more than you wanted to know, but I thought I would lay it out here anyway.
Craig
Craig, I am one who believes that one can never have too much information - if you don't understand all of it then you ask questions or do research until you do. This is especially true when it comes to my Packards!
Oddly enough, at least to me, I do understand what you and Tim are saying and I find it a little reassuring. One question I do have: Does 3,000 rpm translate out to about 55-60 mph on a '55 Patrician with (I suppose) standard rear axle ratio?
My thanks to you and Tim for allaying some of my fears. For to be honest the prospect of staying out of my '55 after waiting 56 years would be harder than quitting smoking. For those who don't smoke or have never tried to quit that means
Damn Near Impossible! Since school is out for the year it occurs to me that if my Packard were receiving grades, on the subject of Oil Pressure: The best it could hope for is a "Gentlemen's 'C'".
Again, my thanks to the two of you as well as Randy, Rowdy, Jack, and everyone else who has chipped in ideas. Any more ideas a certainly welcome.
My God, I almost forgot Howard - to whom I am so deeply in debt as to never get out.
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