QUOTE(ClayPerrine @ Nov 27 2019, 08:25 AM)
The secondary oil relief is not needed. It just drops pressure to the flywheel end main and the #3 rod bearing. I had it stick open, and it ate the #3 rod bearing on the motor.
There is a part out there ( I am at work and cant remember the company name) that replaces the piston and return spring with a solid rod. I would suggest putting that in the case so you never have to worry about oil pressure drop again.
I found one of these rods in my GA004310 engine. I'm not convinced they are the right thing to do. Cold oil and excessive pressure actually pushes the crank against the bearing and can lead to premature wear on cold start. Remember the oil galley is only one side of the case. This results in asymetric pressure.
Pretty much the same situation for lifters.
No right answer for every situation but I cringe when I hear things are not needed. OEM's don't machine cases, and give away parts because they are not needed.
We can debate the merits of a potentially defective design, possible contamination (debris) that might have led to the relief valve sticking in the 1st place on Clay's engine, whether it was needed for solid lifter and not needed for hydraulic lifters, etc.
Once upon a time standard 914 lore was that the thermostat and cooling flaps were not needed. That has subsequently been proven to be false though it took over a decade to undo that myth.
Clay certainly has a lot of experience with 914's so I don't want to undermine his knowlege but rather give pause to why relief might be there in the 1st place.
As someone that has worked in plants that machined engine parts, I can tell you mistakes happen. Parts get mis-machined. Bad parts occasionally get missed. No one is perfect. Porsche (really VW) was no exception to this especially in the 70's. Here is the flywheel end of my early 2.0L case GA000099. Mis-machined.
Click to view attachment Happens!
However, if the case doesn't have it, I don't think I would go to the trouble of machining it to accept a relief plug either given that the aftermarket plug Clay refers do hadn't caused an immediate implosion of GA004310.