Engine rebuild, The reassembly started ! Options

[Valy]

I got a spare engine with my car. The engine looks nice but the PO drained the oil out and left the sump open. Then he wrapped it in plastic wrap and dropped the engine on the left head so it has a nice crack.
Got myself a new pair of heads that are rebuilt right now.

It's going to be a big L-Jet as I don't have the patience to deal with the old D-Jet (although I have all the parts for a D-Jet). I
I'm going to make it a 2056cc unless in change my mind and go crazy with a bigger crank (IMG:style_emoticons/default/idea.gif)

I started taking the engine apart and going to document as much as I can.

Not my first rebuild but is my first Type4 rebuild so wish me luck!

Today I got pistons 3 & 4 out.

#3 looks nice, not too much signs of wear. The ring gaps are about 1mm (trash)
#4 is also nice but the piston got a small bent while trying to remove the pin. That bent trapped the oil ring. Never mind, I'm going for bigger one anyway.

The cylinder registers are nice. In fact, the entire case is very nice and clean.

Anyone knows the meaning of the inscriptions on the cylinders and pistons?

[Valy]

Oil Pressure Regulator

I had a different thread on this topic on the 914club site. Thanks to Chris and the Dr for helping out.

My case has a single oil pressure relieve and I used a higher volume oil pump. The pump is capable to create higher oil pressure if not properly regulated and since my case only has one regulator I had to pay special attention to this issue. I wanted to make sure I don't blow away the oil filter, galley plugs or gaskets.

The dilemma was to find the right spring for the job. I had 2 springs from 2 different cores with different and noticeable compression constants.

So here we go:
The sump groove starts 14.5mm below the valve top position.
The springs are pre-compressed inside the cylinder by about 15mm.
The groove depth is 5mm so when the valve piston is 5mm below the grove start, the maximal bypass opening is achieved. Total spring compression for maximum opening is about 35mm.
Max desired oil pressure 80-100PSI before the gaskets or cooler will blow off.
Valve diameter is 16mm. That makes its area 0.31 Sq. inch so the force on the valve at 80PSI will be 25lb.

I need a spring with a compression constant of below 35mm/25lb=1.4[mm/lb] (yes I know that I'm mixing measuring systems but I'm still OK (IMG:style_emoticons/default/smile.gif) )

So I grab the spring in my caliper and sit the caliper on it head on the table. I stand on the same old bathroom scale I used for the torque wrench calibration and compress the spring in the caliper using my weight. I note the compression and the weight applied delta for different weights for both springs.

Compression constants (k):
Spring #1: 1.32 mm/lb
Spring #2: 2.07 mm/lb

The max pressure regulated by those springs:
(max travel/k)/valve area

Spring #1: 35/1.32/0.31=85.5 PSI
Spring #2: 35/2.07/0.31=54.5 PSI - this is too low.

I'll use spring #1.