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I think you'll find and perhaps JV will respond in more detail that there is a very wide degree of variation in original V8 engine life, some going well beyond 100,000 miles with no problems, and others with problems very early on, perhaps at 40,000 miles of thereabouts.
Very true. However most of the engines we build do not come with mileage and maintenance history. That has been long lost. These are the constants we find:
1. Main bearing wear is the serious failure area. Most Packard V8s by now have had the crankshaft main journals reground at least once - sometimes ONLY the mains and not the rods. This suggests these were a dealer warranty repair and not a high mileage wear issue. We're still trying to determine the design flaw which causes this. It could be as simple as air in the oil.
2. Re-bores are rare. Few Packard V8s ran enough miles with the original owner and were worth so little used, so they were never completely rebuilt. The OEM pistons are not especially strong. EVERY standard shift '56 Studebaker Golden Hawk engine I have torn down, some pistons were cracked where the round skirt meets the flat strut reinforcement. Also, the OEM engine did not take kindly to high revs. Every one of the '56J standard shifts showed evidence of a piston replaced due to a dropped valve. Many sedan engines have collapsed piston skirts. When we are re-using OEM 374" pistons in a .125" overbored 352", we have to go through three or more 374" engines to make one set of eight good pistons. Surprisingly, one 374" engine had .003" oversize piston pins in STD bore pistons. We still don't know what that was all about.
3. Valve guide wear seems no worse than other engines of the era. The Packard V8 has long valve guides, large valve stems, geared for low RPMs, light valve spring pressure, gentle cam ramps; consequently valve stem wear is not the worst wear area overall.
4. Rocker arm tips show wear and have to be reground. If there is lifter clatter, there is also clearance between the rocker arm tip and the valve stem and this causes more wear.
5. Rocker-arm-to-shaft wear is an expensive area to address during a rebuild. I only know one rocker arm rebuilder who does re-bushing and it is $350. If the rest of the engine is tight, there will usually be enough oil pressure to go around.
6. Inside the rocker arm shafts are ALWAYS full of crud. The soft plugs in the ends of the shafts are a PITA to remove. We clean the shafts inside, but no one else ever seems to mention doing this necessary chore on a rebuild.
7. We have only ever seen one camshaft with a flat lobe. Most could be re-used as is, but we always regrind them for use with new lifters.
8. Valve seat recession is not usually present, as many Packards died before unleaded fuel. We always install hard exhaust seats.
9. FWIW, we don't have a problem with the OEM bypass oil filter. If the engine has been thoroughly cleaned during the rebuild and the oil is changed regularly, there will be no problems due to the oil filtration.
Just a few lessons learned from seeing the insides of many engines.
thnx, jack vines
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