Trueing up cylinder heads

Big lumps of metals and spanners.

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dave friday
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Trueing up cylinder heads

Post by dave friday »

I've been told that removeing metal from the cylinder head face does'nt raise the compresion ratio because the head is flat,but the valves must be closer to the pistons? so is'nt the compression ratio increased?[even by a small amount].Is there more chance of the pistons hitting the valves?.
ta.
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camper
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Post by camper »

When i had the head skimmed for a 1.6td recently the engineers checked first that the head had not been skimmed.The head had a two hole gasket when removed from the engine.Apparently it was within limits for a head skim and would be provided with a three hole gasket which is slightly thicker to refit .The point you are making about the valve seat is proberly relevent to this.There is limits to the amount of machining material that can be removed ie if the head had been skimmed once before .The gaskets which are available 1/2/3 hole take into acount the piston protruding for TDC on the various 1.6 engines for the right compressions .Maybe the reason why VW say these heads carnt be skimmed is it would not be the same figures as the factory designed them.But in practice using the extra thickness gaskets gets around it when skimmed

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