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Ok guys. Building a new vw engine for my TD and still new at this.
What would be the optimum piston the head clearance measurement be?. Currently I have 65 thousandths with a 20 thousandths shim on the cylinder head as a test measurment. Should I increase the shim thickness or decrease the shim thickness or run with out any shim which would give me a 45 thousandths clearance?Mark,
On my Ghia I ran a stock 1600 dual port and used no shims. Only the paper gasket under the cylinder.Allen Caron
VW based 53MGTD - "MoneyPenny"
"If one thing matters, everything matters" - from the book The ShackMark, I have not seen recommendations for shims except to give you a desired compression ratio. Sounds to me like you really should “cc” your heads. Then, based upon that and the swept area of the piston, you can calculate what compression ratio you may expect. If it is too high, you can add shims as necessary to bring it into an acceptable range considering the gas that you intend to use. Generally (and I do mean generally) unless you have had some machine work done on your engine case/block or jugs or put in a different crankshaft, assuming you are using stock heads, you don’t want or need shims.
The cranshaft is standard & polished, the engine case and heads have been fly cut and I am using a 100 eagle cam and 85.5 mm piston and cylinders. Some say I should use a 60 thousandths clearance and others say I can go to 45 clearance which would mean just install the cylinders & pistons whichout shims etc. Very confusing for a newbe.
Mark, Why did you get the heads fly cut if you are staying with standard 85.5mm/1600cc pistons and jugs? I expect due to pitting or some sign of blow by or leakage?? I would just install head spacers (not cylinder shims) that are the thickness of the cut made. That would get you back to stock with no worries about compression ratio being too high for our crummy gas. Other than that, your best and safest bet is to “cc” the heads and with shims and head spacers (these are different animals), you can put the compression ratio where you want it. If you are interested, I have a new unopened set of EMPI .040 head spacers and also a new set of .020 cylinder shims. Lets get Allen or Mike and a few other opinions I am an at home shade tree mechanic only.
Royal, The heads were given to me by a friend and were already fly cut and completely rebuilt. Additionally a friend fly cut the block etc. We up graded to the 85.5mm/1600cc pistion and jugs and replace the cam with a 100 eagle cam.We worked on it today and with the cylinder gasket only inplace we found that that piston to head clearance would be 57 thousandths which should work fine, very close to 60 thousandths which we think is close to stock.
Should anyone else have any suggestions I am open to all.
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