Originally posted by GregAmy:
I am unaware of any car that allows updating and backdating of hydraulic versus mechanical heads
I believe that as long as the Scirocco 1.8L 8V listing includes the 88 (which it does), the 88 hydraulic head is an allowed option to the 83-87 solid lifter head. I have called and verified this. The Bentley shows it as coming on top of the JH engine in the 88 Scirocco and Cabriolet, and this was never disputed.
Sciroccos did *lose* the right to use 10:1 pistons because of conflicting evidence (Bentley indicated JH at 8.5 with hydro head for 88-up) and/or lack of a clean specimen, but that did not affect the eligibility of the hydraulic head.
Originally posted by GregAmy:
That said, your existing pump will be fine. The pumps used on the hydraulic-head engines were higher volume to account for the lifters, and it does not hurt you to run that pump in a non-hydraulic lifter engine.
Have to disagree. In my experience, a high-volume pump often leads to too much oil accumulating on top of the head and causing problems (at least with tight engines at higher rpm).
Originally posted by GregAmy:
Any additional volume/pressure will simply get dumped overboard at the pressure relief valve. In fact, it's possibly a dependability advantage.
Makes sense, but I think the relief actually gets overloaded.
Originally posted by GregAmy:
The OE pump for the JH engine ('84 Rabbit GTi, non-hydraulic lifters) is 027 115 105E; the pump for the RD engine ('85 Golf GTi, hydraulic lifters) is 027 115 105.
Interesting. I do know that the original solid lifter pump had 25mm tall gears (relates to volume) and a 90psi pressure relief. The early hydraulic lifter pumps had at least 30mm gears and a 60psi relief. Later hydraulic lifter pumps had 36mm gears and a 60psi relief. When I actually tried to order a solid lifter pump a few years ago, everything the dealer listed or could get had at least 30mm gears. I've been saving and rebuliding the 25mm pumps for the racecar engines.
Edit: Correction, Bentley indicates:
JH at 8.5 with solid head for 85-87 (Scir & Cab)
JH at 8.5 with hydraulic head for 88-89 (Scir & Cab)
2H at 10.0 with hydraulic head for 90-93 (Cab only in the US)
BTW, the 83-84 is covered in the earlier Rabbit/Scirocco Bentley.
[This message has been edited by Eric Parham (edited November 08, 2004).]