Deck Height, I'm confused could someone help me out here Options

[stephenaki]

OK, first off, this motor is so much more complicated than my MG motors! So, I started looking at the piston assembly to the rod and subsequent assembly of the cylinder to the crankcase. It was then that I remembered reading on the forums about "deck height."

My understanding of this concept is somewhat rudimentary but the basics, as I understand it, is that deck height is the space between the highest part of the piston and the top of the cylinder head combustion chamber. Please correct my understanding if I am mistaken.

I have also read through several threads discussing how to measure deck height in order to shim it properly, change geometry, increase/decrease compression....my head hurts.

Since I want to get this thing put together properly I need to know the following.

1. how do I measure deck height (depth gauge is best from what I read).
2. how do I determine "IF" I need shims.

Now I know a lot depends on what I have so here is what I am working with.

1.7L crankcase
2.0L crank and connecting rods (no, I don't know the measurement of the rods. If needed, can I measure without re-opening the case? How do I measure them?)
standard 94mm bus cylinders and piston set (new set, pistons are dished)
1.7L heads that were machined to fit 2.0L piston and cylinder (I checked, they fit)

Rods and crank were balanced prior to my getting them and then the assembly, cylinders, pistons, rods, crank, etc. were balanced as a unit.

The PO had a 1.7L crank and rods with 2.0L jugs and no shims were present when I disassembled the motor.

I am venturing into a completely foreign area and concept for me and can use all the help I can get. I am not after anything spectacular, I just want the motor to run efficiently so I can drive and enjoy the car. I don't plan on racing it. HELP!

[VaccaRabite]

The ring gaskets (the ones between the cylinder and the block) are used for spacing the cylinder to get the correct deck height. You want your deck height to be the same between all of your cylinders or you will have poor compression and head leaks.

The head gasket... This is a whole can of worms with really smart folks on both sides. On one side is the VW tech notice saying not to use them on Bus motors. Given that bus motors are pretty similar to ours, and they do provide one extra surface to leak from, lots of guys choose not to use them.

However, lots of guys DO use them, and think that they are just fine and needed. They provide spacing that is critical for finding your proper compression ratio. And if you choose not to use them, you MUST have your heads machined to be perfectly flat against the cylinders. The head gasket was made to deform a little to make up for minute differences in shape between the head and cylinder.

So, there you go.

Personally, I did not use head gaskets when I made my motor, but I also was not making a stock motor.

Zach