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Jim wrote, - Leon has done more, and better, data taking than anyone else I know. This is - really useful stuff to know. I wonder if the combustion chamber volumes are all - the same on these heads. That would change the compression ratio and make a big - difference, and might explain some of his observations. ============================================================================ ====== Most of the data given in that last message was from memory, if more exact info needs to be looked at, look into the archives of this forum, I recorded information as I destroyed engine parts. All compression has been the same, with the same size stock combustion chamber for a bug with the lip or step casted and machined into the combustion chamber. the only time I had a different compression was when I did the ultra low compression that Berg recommended (75 lbs on all four) after that and a set of new heads, I increased it to around 110 lbs by removing the shims from the cylinders in order to meet the stock/tighter deck hight. I was tired of slow take offs (Still slow but better, it is all relative though).I never really checked the combustion chambers with the special tools, I have always gone by the deck hight, same amount of baby oil that fits the combustion chambers and the same pistons, rings, and cylinders that I bought on the first rebuild in 1999 (upgraded with second ring from Total Seal), I never recrossed hatched the cylinders, just tried to place the rings in the same position as always, may not be correct but I did that and still got 110 lbs and still have 110 lbs compression ,(knock on wood) . Cross hatch still visible after 75000 miles, last August, when Mofoco head was replaced with a Mexican VW head. I always use Semisynthetic oil (20W-50) from Valvoline, change oil almost monthly or 3000 miles. I do not know if this affects compression or wear , just more data. Engine pistons, cylinder, top ring and oil rings have around 90,000 miles. the Mexican head has around 15,000 miles since last August, I hope it proves to be as durable as I suspect. LEON MARTINEZ 69 SQUARE 73 FASTY 67 FASTY ------------------------------------------------------------------- List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org