Deck height is a vital engine measurement that dictates rod length, crankshaft stroke, piston-to-head clearance, and so much more. Deck height is simply the distance from the crank centerline to the deck surface of the block.
This really isn’t a critical dimension if a standard rebuild is the goal. But if you’re a performance engine builder and stroker cranks, longer rods, shaved decks, and custom pistons are your thing – then block deck height is an important dimension that demands attention.
Deck height dictates many engine dimensions. It limits stroke, rod length, and piston compression height. This last dimension is a critical part of the rotating assembly equation and is defined as the distance from the wrist pin centerline to the piston deck.
The proper way to deck a block involves using a mandrel placed in the crankshaft main webs to simulate the centerline of the crankshaft. Then measurements are taken from the outside diameter of the mandrel to the block deck surface at multiple positions. This establishes whether the deck is parallel to the crank centerline. Often, this is not the case.
Given inequities, simply leveling a block in a fixture and then milling the deck “flat” could in fact make a bad situation worse. A simple way to evaluate an engine’s deck alignment is to use the same piston to check piston-to-deck heights at the engine’s four corners and compare the numbers. If all the deck heights are within 0.002 to 0.003-inch, consider yourself lucky. This still leaves plenty of opportunity for the block to be “out of square” but at least it will be close.
Deck Heights of Mopar V8 Engines
|Engine Family||Deck Height in.|
|Chrysler LA Race||9.56|
|5.7L- 6.4L Hemi||9.240|
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