2.0 Cylinder Gaskets, Should they be used? Options

[jack20]

Hello,
I had leaking pushrod tube seals and dropped the engine to make the job easier.
I decided to pull the heads to check condition. I’ve done quite a bit of reading about whether or not gaskets should be used between the cylinder and case and between the cylinder and head. Some posters point to a service bulletin stating not to use gaskets.

I have metal spacers/gaskets between the heads and cylinders. I think this engine has been rebuilt once before I got it. It runs well but it’s not as quick as another 914 2.0 I had years ago. Maybe the other car had higher compression and no gasket? I’m wondering if this metal gasket should be there. I haven’t checked for a gasket between the cylinder and case. My 356 has a thin copper gasket between the cylinder and case.

Can anyone shed some light in this?

Thanks in advance,

Jack

[jack20]

I just wanted to thank everyone for responding to my post on whether or not to use head gaskets when I put my heads back on.

The consensus is not to use the gaskets. I don’t know how many miles the existing gaskets have on them and since I now know they’re laminated I would want to replace them. I would rather just buy new base gaskets and eliminate a potential problem.

I’ve done some measurements and determined that my engine is totally stock. Bore and stroke match the engine specs found on the Pelican site.
The German pistons are dished.
The head gasket is ~ .8 and the base gasket is .2mm equaling 1mm of total deck height.

So my choices are to replace the laminated gaskets and substitute a 1mm base shim for the .2mm shim or to buy new .8mm laminated gaskets and re-use the .2mm shim.

Some of you suggested I measure the volume of the combustion chamber to determine the compression ratio. If I do that I will also need to pull a piston to get the dish volume. The heads are stock and the pistons are stock. I can’t imagine I would find much deviation from the stock comp ratio of 7:6 if I do either of the suggested options.

I believe I’m down to these two choices but I tend to over-think things that are new to me.

Please let me know if my logic is flawed. In the meantime, thanks again for all your input. I really appreciate it.

Jack

[Superhawk996]

Some of you suggested I measure the volume of the combustion chamber to determine the compression ratio. If I do that I will also need to pull a piston to get the dish volume. The heads are stock and the pistons are stock. I can’t imagine I would find much deviation from the stock comp ratio of 7:6 if I do either of the suggested options.


Jack

I know I'm going to get blasted for having said this (IMG:style_emoticons/default/stirthepot.gif) (IMG:style_emoticons/default/happy11.gif) but if you can't measure CR and you're staying stock and have very near to stock deck height, you will be fine.

Is it best practice to CC the heads and even things out. Absolutely. All manufactured componets have nominal tolerances that were designed to yield a perfectly functional engine regarless of how the parts intermixed at the time of assembly. Did some engines come with a litle higher CR and/or a bit more Horsepower than the next one? Yup. Did some come with a little lower CR and maybe down a smidge on power. Yup.

Did the factory build them without CC'ing heads and perfectly matching CR cylinder to cylinder. You betcha.

Depending on the dish of the pistons, if they are stock pistons as you mention someone can post the standard CC volume. You could use that and still CC the heads if you were curious.

CC'ing and equalizing CR is all part of the game if you're trying to build the best possible engine you can with the parts you have. Basically working in the vain of "blueprinting" the engine. However, that is not the way mass production assembly lines work.

As a side note, I should mention that deck height is important for for other reasons beyond Compression Ratio. You don't want to go too tight on deck height. If I couldn't measure all components and do CR calculation, I'd make sure to err on having just a bit more deck and a slightly lower compression ratio.