Switching to hydraulic Valve Lifters
01-25-2007, 09:14 AM
#16
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On a standard car the lifters seem to last OK, Porsche did a recall on a lot of the early examples so I would guess that most have been upgraded at some point. In general use we rarely see issues with the lifters.
However, what I can confirm is that we have seen problems with 80,000 mile lifters when used with sports cams, the common problem is that they lose pressure at constant high rpm, i.e. track days. For this reason I recommend converting modified 993 engines to solid lifters for track use, which is ironic really given the initial question of how to fit them to a 964.
I personally think that 964 engines should be left as mechanical, if for whatever reason you fit a 993 engine into the 964 then leave the hydraulics followers alone and enjoy the reduced service costs, but if you then fit cams, billet heads or whatever to the 993 engine for enthusiastic use definitely consider retro-fitting the mechanical followers.
However, what I can confirm is that we have seen problems with 80,000 mile lifters when used with sports cams, the common problem is that they lose pressure at constant high rpm, i.e. track days. For this reason I recommend converting modified 993 engines to solid lifters for track use, which is ironic really given the initial question of how to fit them to a 964.
I personally think that 964 engines should be left as mechanical, if for whatever reason you fit a 993 engine into the 964 then leave the hydraulics followers alone and enjoy the reduced service costs, but if you then fit cams, billet heads or whatever to the 993 engine for enthusiastic use definitely consider retro-fitting the mechanical followers.
