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BUT! The engine shook violently when it was taken off idle rpm. I checked the distributor, sparkplug wires, and sparkplugs - no clue was evident. Extreme timing advance and retarding did not change the nature of the vibration.

I was extremely frustrated and angry. This was definitely not a "turnkey" engine. I went over my installation of the flywheel, clutch, and transmission. There was nothing that could be out of balance. In fact, the flywheel had been neutrally balanced and I had been using the flywheel and clutch assembly for 15 years without problems. I installed a new clutch assembly 1 1/2 years ago when I installed the Tremec transmission and it all operated flawlessly. I mentioned my problems to a friend who used to build and race formula Vs. He said that he understood that the flywheel on a Chevy smallblock 400 cid and 383 cid stroker was different from the ones for a 327 cid and 350 cid engine. I called BRE and asked them about this. They did some investigation and called me back, and the real story is that the 400 cid and the 383 cid are "externally" balanced engines whereas the 327 cid and the 350 cid engines are internally balanced. This means that the harmonic balancer and flywheel are a part of the balance of the 383 cid. A neutrally balanced flywheel on a 383 cid will cause severe vibration.

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