"It would make no sense to cut a good block down excessively just to zero deck it to low cost pistons. We quit using the cast pistons several years ago as they just lower the CR too much, between the 8 valve releifs and big chamfer around the outside of them. We mocked up an engine several years ago that had them installed and cc'd everything above the piston at TDC. Came up with something around 22cc, nearly as I can remember. It was around the same time that we had been working with several troubles 400 engines with the early small chamber heads. We found, through some pretty extensive testing that having the pistons .030" or more below the deck was contributing to running hot/overheating/detonation. During the course of the testing, we tried quite a few "tricks" to keep these engines cool and avoid detonation. We played around with fans/shrouds, pulleys, water pump impellers, radiators and cam timing. For the most part, everything helped...but...once we zero decked the block(s) the gains were monumental! Despite increasing the CR a bit, we found that these engines ran about 20 degrees cooler, did NOT heat up at interstate speeds during long cruises and made more power. Since then we have been building our pump gas iron head engines right at 10 to 1 CR, and closer to 10.5 to 1 with aluminum heads. To date haven't had the first trouble with any of them on a steady diet of pump fuel. My own 455 was raced with 89 Octane fuel on a few occassions when it still used the iron 6X heads and ran exactly the same as it did with 93 octane! We even pulled the engine down last year and inspected the rod bearings after two full seasons of street and strip action, they were in perfect condition......Cliff "
