Engine not running right, overheating

OK, the car was not idling and was overheating at the drop of a hat at the start of Summer. Why is that? The answer wasn't obvious at all!

Compression test.
Most cylinders showed 135PSI, one at 105, lowest at 100.
I suspected a blown head gasket, so off with her head!
The gasket was OK, but the valves looked a bit the worse for wear: Pitted and with black crap coating the back.
More disturbing was that there were two water holes which were blocked by the gasket. No wonder it was overheating. The new gasket had the same blockages on both sides (front and rear) of the engine. I made holes for it, as you can see:

Engine with new gasket

It's the big one with the big red ring around it. No idea why it was not punched out, it might have been a tooling error.
Jobs to do:
1. Make holes in gasket. Your gasket might already have them if you're lucky. My dad was very surprised this one didn't.
2. Clean the head.
3. Remove then grind in valves.
4. Reassemble

The longest task is #3. Grinding or lapping in the valves is very time consuming. The head was unlikely to have cracked or warped so I didn't get it checked. Cast iron is very rugged.

The gasket was very hard to make holes in. A drill with the round hole attachment is a good choice. It's not like a regular gasket, it has metal in the middle.
The head cleaning just required a wire brush attachment. I did this then removed the valves, which requires a special tool that looks like a big G clamp. I cleaned up the valves and inspected them. They were OK, but pitted and they needed to be lapped in again.
This is the time-consuming bit. It requires valve grinding paste, a little light oil or thinners and a sucker.

Place sucker on valve

paste

Place the sucker on the valve and a small amount of the coarser paste around the valve, where it contacts the head with a drip of something lighter (thinner is ideal) which reduces the friction. Grasp the stick between your palms and rub like you're starting a fire with it. Also, lift the valve every so often. Not sure why but my dad swears it's important. When it feels smooth, remove the paste and inspect the surfaces. If they aren't completely smooth (you can still see the pits) repeat. I had to do this between 6 and 10 times before it was smooth. When it is, finish it with the smooth version at the other end of the tube, just the once. It took me two hours to do 12 valves.

OK, reassembled the head, connected everything and dad told me the valve clearances will need to be set. This is another place where you really need to be careful. The slant six requires the engine to be running and hot to adjust this. The setting is 0.010" (ten thousandths of an inch) on inlet valves and 0.020" in the exhaust valves. Now this is important don't fail to set the valve clearances again when the engine has warmed up.
I did, and had it running on five cylinders until I'd worked it out. The adjuster is 7/16" so get a ring spanner and re-adjust. You'll find the idle speed will change radically if yours was anything like mine.
I'd also bought a tune-up kit at the tip shop and it included a vacuum gauge. This is useful for getting the idle mixture right. Maximise it and your car will love you.
Mine seems to love me now. She idles better than ever (as in has literally never been this good) and is smooth and powerful. Also doesn't overheat as easily. Have to get the radiator sorted out next and I just might get through Summer!

Finally fixed the cooling

Well, after two weeks with the new system, I went back to the old one. Here's why:
No matter what I did, there was a massive delay from turning on the fan to dropping temperature. Another problem was that the system wasn't pressurised properly. Firstly not at all, so I blocked the overflow. Still made me very nervous. In the meantime Dad removed the top of the car's original radiator (with heat) and checked the flow through the core. Quite a few of the passages were blocked with "rust and shit" (don't blame me, I'm just quoting). He cleared these and soldered the top on again. I decided to play it safe and:
1. Keep the a/c fan
2. Keep the six bladed fan I was using before the electric experimentation
3. Use the long fan spacer

The radiator leaked, probably through one of the formerly blocked passages. Stop leak fixed this up and even on a hot day the temperature barely gets to half way.
Moral is: Restore the car, don't try and update.

Another Summer and more cooling problems

Well, since the crappo Chinese fan seized and the crook who sold it never sent me a replacement, I decided to do things my way.
Went to pick-a-part and picked up a radiator from an Alfa, transmission cooler from a BMW and a fan from a Mercedes.
The range of bits was for good reasons.
The radiator had to be a certain size. Well, it had to be about the same size as the Valiant one. The Alfa was perfect (really, almost exactly the same size) as well as being quite thin. I got the fan that was on it. All this for $103.50.
Transmission cooler was from a different wrecker: One near my dad's and they charged $36! Hell, that's expensive.
Can't remember what the merc fan cost (got it ages ago) but it wasn't very much (also from P.A.P.) - probably about $25.
OK, so radiator almost went straight in. Both hoses were on the driver's side like the Val, and I set it up so the bottom hose went into the new one. Got a couple of rubber blocks to set it on and found out that it also lined up nicely with two factory drilled holes in the bottom support panel! Just had to secure it at the top, but out it came and the trans cooler had to go in first. I'll get pics tomorrow. It's nearly finished now but I just haven't taken pictures yet.
The cooler had to be modified. I cut it off at the rubber hydraulic hoses and for the Val, I hack sawed the pipes back to the steel. When this had been done I thoroughly cleaned up the cut and the inside of the pipe. The adapters that go into the radiator fit into the end of the steel pipes like a glove, so I screwed them in. They were quite secure, but I unscrewed them, mixed up some industrial strength araldyte and spread liberally onto the threads before screwing back in. Left them for 24 hours to set before tightening.
So, cooler, radiator and original fan... No, the original fan is massively too wide. I tried to modify it to fit (it had a steel shroud damn it!) but no go. Mercedes fans are an amazing combination of heavy duty and efficient design. It was easily half the width of the Alfa fan, so on it went. This required a bit of stuffing around but I got there  in the end. Radiator must not touch the fan housing or the transmission cooler. All of these things would rub holes in each other so make sure they don't touch.
OK, so the Alfa radiator has a thermostat, so I have to learn what sort of output it has and rig up a thermo switch to come on automatically, cool the car down and shut off. The temperature of activation must be higher than the temp of deactivation. If not, it would be coming on for a few seconds at a time every few seconds! Not what we want, so we have it come on around, say, 90 and switch off around 85. It'll have to heat back up to 90 until she kicks back in.
I'm currently researching this feature but there's plenty of information about cheap or free ways to accomplish it.
Also have to get the A/C to activate the fan, or even put in a second one. I did buy two so it's possible, but I'll see how she runs with only one. Thursday will be a good day to test it out, seeing as it's expected to be 40 in Melbourne!