Quote:
Originally Posted by dannobee
Re: Case. Porsche machining isn't as precise as we use on race motors. And I get it, for the vast majority of production engines, it makes no difference. And things happen when put in service, things shift around.
But if you've measured your cylinders and one is sticking up proud, then you've found your problem. You don't really need a base gasket, you could always seal it with threebond and be done with it.
We check deck height by assembling the cylinder and using the cylinder holding nuts to clamp everything down, without the head. Then rotate the piston up to TDC and measure how far the piston is down in the cylinder. Your 6 cylinders should be close.
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I respectfully disagree with everything said here.
It always makes a difference, hence the issue at hand. Building an engine always starts with establishing that every parts is correct and to spec. Checking the case halves are of equal width, the cylinder base faces are flat and parallel. The cylinders are all the same length and the heads are the same heights.
Engines should be assembled dry with the case, cylinders, heads and cam housings with no internal parts fitted, checking the cams turn in the cam housings. This takes little time to check and saves a huge hassle later when the engine is all assembled.
Do not use glue to take up any differences!!!!!! That is absolutely a "no no" and expect problems if you do.
Do not confuse "Piston" deck height with "block" deck height. They are completely different. When measuring the block deck height, ( which is the issue at hand) the crank stroke, rod length and piston compression height make zero difference. Piston deck height is all about the stroke, rod length and compression height, which in turn become a factor is piston to head clearance and compression ratio.
To measure the piston deck heights per cylinder and use this a factor in making sure the cam with turn is wrong.