I have begun to take apart the car (intake manifold, fuel rail, airbox, timing covers, etc..) to replace several seals and the timing/balance shaft belts. The car is a 1986 944 Turbo, but in 2004 the PO replaced the block with an M44.52 short block from Porsche (which is verified by the M44.52 stamping on the side of the block). I was under the impression that the earlier eccentric roller tensioner would not fit onto a later block since the necessary threaded hole would not exist (covered by the sprocket on the spring tensioner), but when I pulled the timing/balance covers the old eccentric roller tensioner is being used. Did Porsche drill the eccentric tensioner hole on earlier blocks despite not using it post-1987 or did the PO somehow retrofit the eccentric tensioner to the later block in order to reuse the existing tensioner? Would it be worthwhile to switch to the spring tensioner, I am assuming not since I have the 9201 tool and the spring tensioner unlike the later 968 hydraulic tensioner is not a true auto tensioner since once it's locked down it's tension profile is identical to the early tensioner?

 

The late blocks have the same M10 hole in the block with a bolt (in place of the tensioner stud) installed as part of the oil pump fastening.