01/14/2026
Here is one way to measure your deck height with basic tools on an Aircooled VW engine. For this video we used a set of dial calipers, deck height tool part number 5756, and a marker. This measurement way is suitable for a reasonable compression ratio street engine.
After removing the cylinder head, keep any shims for the final measurements. Install the deck height tool, screw in the set screw, and rotate the crank to touch the piston to set screw. Mark this position on the flywheel or pulley - we use the case half as the alignment. Rotate engine back the other way until you touch the piston to the set screw, and mark the flywheel or pulley again. Between these two marks is TDC - Top Dead Center.
Back off the set screw and rotate to TDC, then measure your depth with the dial calipers. Measurement should be on either end of the wrist pin to minimize the piston rocking.
Take this depth measurement (Ours was 0.576” depth), subtract the thickness of your deck height plate (ours was 0.450”), add the thickness of any head shims (one 0.060” shim on this engine) and you have your deck height total. We do recommend measuring cylinders on both sides of the engine to help verify your crankcase centerline.
Our engine measurements as example:
Our depth was 0.576”
Our deck height plate thickness 0.450”
One cylinder head shim 0.060”
0.576” depth
-.450” plate thickness
+.060” head shim
=.186” deck height
Use your deck height measurement in an engine calculator, along with cylinder head CC, to help calculate compression ratio.
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