Engine Build #1: A Costly Failure

A pile of shredded valve stem seals. This was just the beginning.

Ever since the initial break in of the engine redone by Thompson Machine, I noticed an unusual amount of black smoke. After getting tired of the constant cloud behind the car, I pulled the valve cover and found damaged valve stem seals. I replaced them and checked again a few weeks later, only to find the new seals already chewed up. I contacted Thompson Machine, and they were adamant that the custom Comp Cams specs were referenced when they ground the guides and installed the valves and springs. I had my doubts.

I kept driving for a few more months, swapping seals regularly, before I eventually decided to pull the plug and stop driving it altogether. When I finally tore the block apart, the hard truth came out. The shop clearly ignored the camshaft specs, leading to the seal failure, but that wasn’t even the worst part.

Scoring on the side of the Ross Racing Pistons.

The wrong oil rings were used on the Ross Racing Pistons. This mistake destroyed the pistons and allowed excess oil to dump into the combustion chamber, which explained the smoke. When I took these findings back to Thompson Machine, they refused to honor any kind of warranty. Their excuse was that because it was a “Custom Build,” it didn’t qualify for their typical coverage.

Evidence of oil entering the combustion chamber on the piston top.

It was clear that this first engine rebuild was a total failure. The shop’s negligence put the entire build at a standstill. When you pay a professional to follow specific tolerances for high end parts, you expect them to actually read the spec sheet. Instead, I ended up with a pile of scrap metal and a hard lesson on who not to trust with my machining.