We never did find anything wrong with the engine. The oil filter is clean, lash is fine, plugs look good, compression is identical in all 8 holes, etc.

We calibrated the dyno and double checked everything we could think of. Could be that we're just at the limit of this cam and head package which is why changing things like spacers and carbs and such doesn't make much of a difference. We made about 30 dyno pulls over a period of several days and all the good runs ended up being about 820 hp.

All was not lost though, we did get to test a ton of parts and we tried a bunch of new things. Most of the new stuff didn't work out, but that is still useful information.