Cylinder base shim needed?
 

I'm looking for a little help from those who know. I'm putting together a 2.0 with L pistons and cylinders. I measured the deck height today using the CE method in Wayne's book, but it seemed way to large at 2.2 mm. According to the book, it seems like the suggestion is to remove the .25mm shim to decrease the deck height and bump up the compression ratio a bit and bring it all back in line.

Is there an issue if I run without the cylinder base shims? I've built type 4's and FV race engines without the shims to get max CR, but they were also engines that would be torn down frequently. This engine will not be one of those! Will this lead to oil leaks, etc. down the line?

Of course, I have all of the barrels on without shims before I started thinking that this may not be a good thing...

Thanks,

Dion

If you really need to remove the shim then you don't have alot of options. One thing you could do is have the case machined at the spigots but that's alot of time and expense. I haven't tried to build an engine without the shims. Maybe someone who has tried this can comment. I would suspect you'd be ok if you use some non-hardening sealant on it like Curil T.

-Andy

What about the spray-on (or brush on) copper gasket maker? I've used it on Type 4's with success before, and it provides some sealing with a much thinner profile.

Curil T may be a better solution.

Dion

I'm not familiar with the copper gasket maker. The main thing is you can't use a hardening sealant unless it sets very slowly. You have to be able to put the heads and cam towers on and torque everything up before the sealant sets. If you don't the sealant will be in varying thicknesses on the cylinders and you'll find the camshafts will be in a bind. One of our fellow pelicans went through this recently.

-Andy

Andy, thanks for the tip. Makes sense.

Dion

Assuming the crankcase spigots are all on the same plane, why not use the suggested base gaskets, but trim all the cylinders an amount to arrive at the desired deck height? Machining the cylinders will also verify all cylinder heights are equal.

Sherwood