I GET CRANKY

I experienced a setback with the engine in Gary's '51 Chevy coupe. While driving it to town I noticed that it had low oil pressure and limited power. By the time I arrived at the muffler shop to have the exhaust system installed, it had a definite knock to the engine. I left it and came back with my tow dolly to haul it home. The car languished in my driveway over the winter and this past weekend I moved it back into the shop to remove the engine. 

I felt like a coroner taking the oil pan off looking for a sign of failure. I expected the worst, but was surprised to see everything looking pristine. 

I first took off a rod cap and placed a piece of plastigage on the journal. Then I torqued the cap back down. Removing it again I could then measure the thickness of the squished plastigage. It was perfect. I was baffled. It wasn't surprising to see the perfect clearance, I'd gotten used to trusting the work from my friend Bryan at K&U machine shop in Sunnyside. 

I took all the pistons & rods out and inspected everything. Everything was in perfect order. It was interesting to see the amount of wear on the bearings & piston skirts. 

Then, I put plastigage under one of the main bearing caps. When I pulled the Capp back off I was shocked to see that it hadn't compressed at all. I measured the diameter of the crankshaft and then looked at the markings on the back of the main bearings - then it was obvious: I'd installed standard size bearings when the crankshaft measured machined to ten thousandths undersized! No wonder the low oil pressure and the knocking.