Engine Deck specifications

[John LaVoy]

Thanks for the input on the engine coming from Ford. Is the consensus on what the deck should be before it needs to be milled during the rebuilding process. Maybe that is the place to determine if there was some standards for how flat the top of the engine should be.

[Jim Brierley]

I don't recall seeing anything written on this but would thing .006" would be a ball park figure?

[John LaVoy]

Thanks Jim, that was the number I had heard before. I am assuming it is a number that has become a standard from use by machine shops, rather than by any specification. My last engine has had about a 1/4 inch removed from previous surfacings and was curious at what point the shop decides that surfacing the block is in order.

[Tom Wesenberg]

When I check heads, I like to keep the side to side at .002" or less and the end to end under.006". I would think block decks would be similar.

[Bruce Lancaster]

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Decking is often routinely done...it probably should not be. Model A's, B's and in fact most popular engines are thinner at the deck than would be ideal, and removing down to flat for a ninor variance can easily be seen as destructive. The flatness is something of an illusion, anyway...it is flat at 70 degrees and with no fasteners, not exactly operating conditions! I think all engine builders recognize the several kinds of distortion that occur when head studs are tightened and compensate especially for the bore and seat distortions by using surface plates in boring and seat work. Other types of distortion probably cannot be analyzed and compensated for...it would be pretty difficult to mill with a surface plate on there!