Van

The oil pressure relieve valve also has to be removed - this way it will be easier to clean that case half (and inspect the plunger).

The valve is under a large cap with a flat slot underneath the oil cooler mount. I was able to easily unscrew this by tapping sideways at one edge of the slot with a chisel and hammer.





Behind the plug is the spring.





And after pulling the spring out, I was able to stick my pinkie in the hole and pull out the plunger.





On the side of one case half, there is this bolt/plug which houses a secondary oil pressure relief valve:





It is removed with a 14mm triple-square socket. In side is a spring:





And a plunger (which can be removed with a magnet:

Van

I decided to clean up the fan shroud next. I decided to take it apart (mostly because I was curious what it looked like inside), but also because I thought it would be easier to clean.





There is a set of flaps inside this shroud that can either direct airflow to, or away from, the cylinders and heads. This is used to help the engine warm up on cold days. The flaps are connected to a spring loaded linkage that is controlled by a bi-metallic bellows (that expands and contracts from heat). I don't have that bellows and don't drive the car in the cold, so I leave the flaps "open" all of the time.





Anyhow, after removing the two screws that hold the linkage bar in place, the flaps can be separated from the shroud.





And, after undoing the perimeter bolts of the shroud, it can be opened up:





After a thorough cleaning with a degreaser and elbow grease, the shrouds were cleaned up well.





So I decided to treat them to a coat of silver paint! That should give it a nice "extra touch" once it's all back together.

Van

According to Jake Raby, there are 5 oil galley plugs which are prone to failure. He replaces them on every build. I thought it would be a good idea, too.

One side of the case (with the distributor and oil cooler) has 4 of the oil galley plugs Jake recommends replacing. The first step is locating them (these are the two plugs near the oil filter housing):





Second step, drill a hole in each one:





Third step, tap the hole so you can thread in a bolt (I used M6 - because I had the tap and I had bolts laying around... plus, that was a good size to use with my slide hammer!):





My slide hammer has a little "hook" attachment that fit nicely under the head of an M6 bolt:





A few yanks on the slide hammer, and the plugs pop right out (all of mine were pretty tight). Here I've just started dislodging the first one:





And here the front two are out:




Here are the two plugs on the back side of that same case half:





And here is the fifth and final plug on the back side of the other case half:





Now that all of the plug are out, it's time to drill and tap the holes for 3/8" NPT plugs. Luckily I have a tool over in the corner of my garage that makes this an easy task...





After drilling the holes, it's time to tap them. To make sure the tap goes in straight, I use an old center drill (lined up with the hole) to stabilize the top of the tap while I start the threads (now you know why large taps, and your tap handle, has a hole or divot in the top!)





And, finally, the holes are tapped and ready for thread-in plugs (after everything's all cleaned up)

Van

Now that the two case halves are completely disassembled and tapped for the new oil galley plugs, it's time to do a thorough cleaning.





After some time using a degreaser, a razor blade, a scrub brush and an old tooth brush, I have have an engine part that I'd proudly leave on the floor for my wife to trip over...

skl

What is there to fail on the those oil galley plugs? Do they leak? My engine is 36 years old- I rebuilt it about 20 years ago but only have maybe 20K miles tops on it since then and no issues with those plugs as far I know...


BTW- this thread is very interesting- keep the pix coming as I have a '73 2.0 engine to do one of these days...

Van

According to Jake Raby's experience those galley plugs can loosen over time. All mine were pretty tight, so they probably wouldn't have failed. But I had the tools to do it and I'm going to run a higher volume oil pump, so it sounded like a good idea.

An added benefit is that you can clean a little extra sludge out...

Here it is from the horse's mouth: http://forums.aircooledtechnology.co...hread.php?t=72

Glad you like the pics!

Matt Romanowski

Be carefule when you clean put npt plugs in the oil galleries. Some of the plugs need to be shortened sot hey don't affect the next port...

Van

Good point, Matt! I've been controling that with my thread depth (it only applies to the front 2 holes on my engine - not the 3 behind the flywheel).

Matt Romanowski

The 2 on the front by the filter console are pretty critical. Remember, there a standard for NPT threads (normally 3 turns in) that will dictate how far in you have to run a tap. If you use a regular tap (not bottoming), you'll have trouble getting the plug in and will only have a thread or two engaged. If you get two taps and grind one down, you can make sure you get 3 turns in and still not be too deep.

Van

Yes, a bottoming tap is needed to do this correctly. With my plugs, there isn't a risk of blocking the oil flow, however - there is 0.450" of clearance between the top surface and the holes for the oil filter housing. 3/8" NPT has a thread-pitch of 18 threads per inch - which gives me room for a max of 8 threads of engagement. My plugs only have 8 threads on them.

Van

One of the advantages to cleaning the engine case halves in my utility sink with a toothbrush is that I get to intimately learn every little nook, cranny, crevice, boss, indentation and casting mark. One of my goals for this rebuild is to make as leak-free an engine as possible (for the last several years, half of my garage floor has had a continual pile of kitty litter absorbing the oil this car has leaked).

Anyhow, I noticed that the mount for the oil pressure switch (the sensor that triggers the low oil light - which I'll be replacing with an oil pressure gauge and sending unit) was at an angle. To be more precise, the mounting surface, which is sealed with a little copper washer/gasket, is not perpendicular to the threaded hole (due presumably to draft required to remove the pattern from the casting mold - I suspect the case halves were made with the plaster casting process (for those interested, here's the Wikipedia article about casting: http://en.wikipedia.org/wiki/Casting )). To get to the point, this angled surface prevents the sensor/sending unit gasket to properly seal.

This means another opportunity to use the Bridgeport! I threaded a tap into the hole, then used this as a reference to align the case half up with the milling machine. Once the tap was lined up with the centerline of the spindle, I was all set:




After shimming and clamping the case to the table, I removed the tap and used an end mill to machine a nice flat mounting surface:



Hopefully that will solve at least one oil leak!

Van

One evening I had a little time, so I decided to check the piston ring measurements. First I checked the ring end gap for the first and second rings. The gap is important to ensure the ring doesn't bind up due to heat expansion - of course too large a gap will compromise compression...

All of my rings had a gap of about 0.022"





Next I measured the clearance of the grooves machined in the pistons - which is about 0.0025"

Van

Now that the case halves are clean:





And I'm happy with the way they fit together:





It's time to do some test assembly and get some measurements.

For this, I'll use my "special engine assembly table" - really it's just a table with a wood top that I've drilled holes in so the head studs can pass through. I used this table for my 944 engine and it worked superbly! Anyhow, here's the #3 / #4 case half on the table:





The new bearings fit nicely on the new crank, and it fits nicely into the case:





Put the other case half in place and tighten the 6 through bolts:





The crank spins as nice as can be! Silky smooth! So, I bolted the flywheel in place, put a dial indicator on it and was able to measure the crank end play (which was 0.047"). There are three shims that go between the flywheel and the thrust bearing (rear most crank bearing) - by getting the right size shims, I can bring the end play into spec.





Next, I put one piston and rod together and put it in the #1 cylinder spot. After sliding a cylinder over it, I was able to use my new homemade tool - a dial indicator mount that I'll use to measure deck height and TDC (top dead center - or the very top of the piston's travel before it starts moving back down):





By turning the flywheel slowly, I can watch the needle on the dial indicator and find the exact top of the piston's travel. (This same tool will be used to measure the deck height (the distance from the top of the piston to the top of the cylinder). It looks like I'll need spacers 0.146" thick between the case and the bottom of the cylinders to achieve a 0.040" deck height.)





It's interesting to note that when the piston is at true TDC, the mark on the flywheel is lined up here: (I assume it should line up with the split between the cases... I will measure TDC for all cylinders to verify the crank was ground properly.)





It is even more interesting to note that the timing mark on the impeller fan is considerably off location - perhaps as much as 5 or 10 degrees! (I will, of course, be putting a new TDC mark on that...)

BADpolizei

Great work, I would love to do a project like this sometime.

Van

I came across a deal on an Electromotive ignition module, so I figured it would be a fun, challenging modification to make to my engine. Instead of a distributor and coil, this works off of a "trigger wheel" - a metal disk - that's mounted on the crankshaft. A magnetic hall effect sensor can determine both engine RPM and TDC - the control unit has coil packs and fires the spark plugs directly.

Anyhow, I now have to figure out how to mount the trigger wheel and the magnetic sensor. There is a metal spacer between the fan hub and the fan, so I figured an excellent solution would be to replace this spacer with the trigger wheel.

My new oil galley plugs on the front of the oil filter mount seemed like the perfect place to fashion some kind of sensor mount. I got some plugs that have a recess for an Allen wrench - this enabled me to weld a stud onto them, and then weld on a large nut to provide a) a way to tighten down the plug, and b) a surface to bolt the bracket to:





Next, I started fashioning a bracket out of aluminum (it's easy to machine and doesn't interfere with the magnetic sensor):





My mounting holes are oblong slots for adjustment. And here is the block that will hold the sensor (which will slide up and down for adjustments):





A quick check to make sure the bracket clears the fan shroud, and you can see the trigger wheel on the hub:





The trigger wheel is 0.040" thicker than the original metal spacer, so I machined down the mating surface of the fan to accommodate for the thickness difference:





The fan clears the bracket, too!





Here's the clearance on the back side of the fan shroud. Mission accomplished.