an easier way to measure deck height? Options

[Jakeodoule]

After reading lots of post on measuring deck height, as well as searching the internet on ways to measure it. I thought there has to be an easier way…

I made a plate that fits on the cylinder. Make sure it’s a good thick plate. I then drilled holes right above the outer part of the bore on both sides. Bolt it down tight.


Then I just zeroed out the digital caliper on the upper ring of the cylinder. I checked zero on each side of the plate to make sure its flat.

Moved it to one of the piston holes that I drilled. Pushed the caliper end into the bore and turned the cylinder through…. Then I took a reading off the caliper. It only pushes the caliper in to the point of your deck height.

You have to keep the caliper straight! But I took 4 or 5 readings on each side of the piston and each time I came within .0005 of the last reading. This seems rather simple to me as you do not need to find TDC. Just turn the crank till the piston rises and falls a little bit. In between you just shove the end of the caliper in and let the piston push the caliper shaft up till the piston drops back down and that’s your deck height…

I also saw many posts that said you only had to measure 1 cylinder. Thats bogus because 1 one my cylinders was .009 thou off from the others. I would measure each one if I were you. Also if you don't have any rings in you need to be careful about the piston being tilted a bit. So I just averaged the readings from side to side.

I’m sure I’ve done something that I will be flamed about by all the professional motor builders, but it seems to work for me.
I have thick skin so tell me what I did wrong….

[ArtechnikA]

I also saw many posts that said you only had to measure 1 cylinder. Thats bogus because 1 one my cylinders was .009 thou off from the others. I would measure each one if I were you.

Always good practice to check them all.
But the process depends on what you've done before.
You can check one _if_ in the building process you have previously already verified all the crankshaft centerline-to-cylinder mating surface dimensions, the individual crank throws, the connecting rod center-to-center lengths, the individual piston pin-to-deck dimensions, and (most likely to be an issue with available parts...) cylinder length from lower sealing surface to head mating surface.

Deck height measurement is kind of a final check for all that stuff. If you're finding a cylinder to cylinder difference at deck height measurement time, you have to go back and find the cause, and fix that.

I like the method of using the caliper as a 'telltale' that the piston moves rather than needing to rely on TDC and measuring that. Although in practice, so many things rely on TDC it's something I'd like to verify early and mark (or use a reference like a degree wheel). With a hole in the plate above the point of interest on the piston you could still poke the depth stem of the caliper through the plate for mild domes.

If you have pistons with domes that extend above the cylinder mating surface, you're back to the traditional method...