Block Decking

[tmodel66]

Decking a block has been a topic in several threads before. Altering the identification numbers on a block is always an issue. Blocks are decked for several different reason. Most of the time it is to true or flatten the surface so you get a perfect/near perfect fit for the head.  Sometimes the block is decked for perfection of the head, piston combination. Most of the time the block will be decked on both sides of the engine if it's a V-8. Other times the block is decked to change the ID numbers with a re-stamp.  This practice is not new and probably will never go away. Just for sake of information lets not confuse the practice of decking with grinding for repair of mistakes in the engine ID numbers on the pad. We have seen pictures, that were shared here on the forum, of engine pad stamps that were ground off and re-stamped at the factory. That cannot be compared to decking. That is the pad. The pad was used for stamping these engine/vehicle ID numbers.  The deck of a block is the entire surface area of the head mating surface of the block.

Disclaimer : This is solely my observation. Any views or opinions presented in this post are solely those of the author and do not necessarily represent those of the CRG.

[mopar346]

Back in the day and still currently for normal blocks we had al kinds of machine work done to prep a bloick for a build. Many/most of the times it included decking the block, we gave no thought to number what so ever we were just worried about the build and getting everything perfect. There are cases where we would deck it enough to raise the compression and it would be enough that you had to mill the 2 parts of the block the intake sits on cause it wouldn't allow the intake to seal against the head. During this time no doubt many rare blocks got there numbers shaved and now there is no way to identify there origin. As with anything when less scrupulous individuals see an opportunity to make an easy dime they will, so it will be a part of the hobby forever. It's a shame that it matters to the point of fraud but it is oen of the things that separates different levels of cars.

[restore-z28]

Daniel, you bring up some interesting points. There are a multitude of reasons why an engine would need to be decked and in most instances would be part of a legitimate repair. I think the line becomes black and white when someone does so to deceive or misrepresent an item as being the "real deal" knowing full well they have done this to separate someone from their money.