Brief chat with the machine shop today. Shocking results!
1. Valve springs are weak, 10-15 lbs lighter than spec. This is likely cause for some of the backfires and a reason why it happened on both carbs. The other leak certainly contributed.
2. "It's about the worst bore and hone job I've ever seen." He thought the hash on that would chew right through new rings. Pistons will be bored out to 0.040 (0.030) today.
3. The wrong pistons were installed at the last overhaul! When I brought the engine in, Bill kept looking funny at the engine. He got out his measuring device, but didn't say much. I thought maybe it wasn't TDC, but it actually was. Turns out that 250 CID pistons were installed with the shorter-stroke 230 CID engine. Rough estimate that the compression ratio was somewhere around 6:1 at best and the cause of my 105-110 PSI compression. This makes me feel good that there was a major defect that was causing this engine to run so horribly and that when it's done with the 250 crankshaft, flat-top pistons and moderate CAM, that this engine is going to SING! I didn't have a good picture at TDC, but did find one. Jim pointed out that ordering the wrong pistons can be forgivable since somebody assumed it was a 250. But how does one put the engine together and not notice? Oh yeah, that's right, considering the boring job, it may have been done in somebody's garage.
Anybody experience this sort of error before?
