The spec'd height of a SB block (350 ci) I believe is 9.025". Does anyone know what the +/- tolerances that were allowed before the block was rejected?
1972 SB deck height
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Re: 1972 SB deck height
I don't know what the tolerance is on the print. Clem has measured a a lot more deck heights/deck clearances than I have, and my results are the same as his. Most are high up to .015". I've run across one that was right on - at least on one side.
It's also common to see .005-.010" difference side to side.
High decks are the primary reason why actual as-built compression ratios are less than advertised.
It doesn't appear they ever rejected or reworked a block because the decks were high, and I have no idea how often they came out low.
The wide variation in deck height/deck clearance is why I harp on it and co-wrote an article about it in the Fall 2009 Corvette Restorer. CR is a very important parameter to achieve maximum performance and fuel economy, and it's not that hard to "manage" starting with measuring deck clearance on all eight when you tear down an engine for restoration.
Do you have any measurements, Jerome?
Duke- Top
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Re: 1972 SB deck height
My deck height at #1 measured at 9.020" and 9.028" at #2. From front to back each side varied from the 1 and 2 cylinders +\- .002" at the other cylinders. I am surprised there is no history of a unit having a minus tolerance from the spec'd deck height.
Does anyone else have any thoughts or comments?
Any other experiences with the other block sizes? 283, 327, 396, 427, 454 etc?- Top
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Re: 1972 SB deck height
My deck height at #1 measured at 9.020" and 9.028" at #2. From front to back each side varied from the 1 and 2 cylinders +\- .002" at the other cylinders. I am surprised there is no history of a unit having a minus tolerance from the spec'd deck height.
Does anyone else have any thoughts or comments?
Any other experiences with the other block sizes? 283, 327, 396, 427, 454 etc?Last edited by Clem Z.; July 23, 2012, 10:28 AM.- Top
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Re: 1972 SB deck height
You have to remember the manufacturing process, the mains and decks were cut in one process using a huge broach. Too much metal off the top would result in a scrapped block, something to be avoided, so the process was set up to be on the "Safe" side, err on the side of caution.Bill Clupper #618- Top
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