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^^^^^
From what I have been able to figure out the magnesium valve covers were used up until 1990 or mid year 91 and they switched over to aluminum at some point in 1991. My 90 C4 had magnesium covers and my 93 has aluminum. Most of the 964's I have seen have aluminum but they are mostly 92 and newer.
It would appear they are factory and used the same tooling as the magnesium parts. The shrinkage of aluminum and magnesium are nearly identical. Although the finish grinding on the aluminum is not the best. Look at the openings for the spark plugs on the aluminum pieces there is far too much flashing for my taste.
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Anthony PCA affiliate '77 member '83 '90 3.8 RS tribute, 91 C4 converted to C2,'93 964 C2, '93 928 GTS M '94 Turbo 3.6, '15 Boxster GTS M,16 GT4,23 Macan GTS,
Gone worth mentioning '71 E '79 SC, '79 built to '74 3.0 RS tribute (2390 # 270 hp), '80 928 euro 5 speed, '74 2.0l 914, '89 944 S2,'04 Cayenne TT '14 boxster, '14 Cayenne GTS 14 Cayman S, 18 Macan GTS many others
Last edited by Cobalt; 06-17-2015 at 03:59 AM..
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