I finally got the coolant system flushed and tested, then properly filled with coolant on Friday. I have this Prestone flush and fill kit installed from last year and finally put it to use. Hooked a hose to it and flushed the whole thing out and filled it with coolant. I ran it quite a while and thought it was safe to take out. Went to take it out for a significantly longer test drive, but ended up stranded again. Overheated again. After being stuck at a stop sign when it stalled before pulling away, I finally limped it home. The truck made it EXACTLY to its parking spot before the engine died again... I let it cool back down and found a few more problems(yay). To start with, it was incredibly difficult to start and barely ran on its own. Previously, it would idle extremely fast, now it stalled at idle. A couple of buddies were looking at the engine when I had it running and started yelling as I could hear the engine dying, so I shut it down. I got out and found that gas was pouring out of the carb as it ran. Not dripping, but pouring. I gave up on it and went to sleep.

Today, I took the carb off and ripped the whole thing apart. This was extremely easy on the Rochester Monojet single barrel carb, and thankfully so. I was able to understand this carb without any documentation at this point, a huge improvement in my automotive knowledge over this time last year. Fuel leakage on these carbs was a common problem I found when the fuel float level was set wrong or the plastic float had filled with fuel and caused it to raise the fuel levels. As I had neither of these problems, and the gasket was good, I knew something was up. With the carb apart, I found that a piece of crud had gotten under the needle valve, which allowed too much fuel into the carb, which caused it to pour out of the hole for the accelerator pump linkage. After corecting this and cleaning out my fuel filter, I decided to bench test the entire carb the best I could. I'm glad I did, because I found that the linkage that opens the flap on top would bind at random. After testing the vacuum actuator that opens this flap, I was able to verify everything was ok. It still bound up, so I loosened an overtightened screw to free up the linkage. I must have sat there for 20 minutes actuating this flap with a Mightyvac before I was satisfied with it. It opens fairly quickly when the vacuum pressure hits 5 inches. It worked quite well for something from 1985 or so.

I did notice that the fans seemed to be running fairly ineffectively. This may be due to improper placement, as I have the 2 12" electric fans mounted side by side, in the center of the radiator. They should, ideally, be mounted offset, with one by the upper radiator hose, and the other by the lower radiator hose. I will have to double check to find the best mounting practice., and mount them properly.

Another MAJOR problem I found, one common to these engines, was a very loose carb mounting nut. These Chevy Straight Six motors are known for vibrating things loose, especially the intake manifold bolts and the carb bolts. Of the two nuts that mount the carb to the intake manifold, one of them was so loose that I removed it with only my fingers. I later guessed that this was the cause of the poor performance, fast idling, and possible overheating, as it caused a massive vacuum leak, which would have interrupted fuel vaporization and possibly caused the engine to run very lean. I re-ran new fuel lines and clamps all the way around while I was under the hood to clear up a questionable fuel feed. I got that sorted out, re-ran all the vacuum lines, and did another inspection before starting it up. Everything looked pretty darn good.

I finally got in and tried to start this thing up. It fired up almost instantly, even with no gas in the carb. It was kind of shocking, really. It made some hideous knocking sounds at first, then it worked out some air bubbles in the fuel feed, and idled nice and smooth. Up until the oil pressure got up to normal levels, there was a pretty loud knocking down in the engine. I attribute this to the fact that I put really cheap oil in it, added a bunch of SeaFoam engine detergent, then ran it hard to knock all the debris out of the engine. From what I understand, this thins the oil out and pretty well wears it out immediately. Thin, worn out oil does not provide a proper surface for metal parts to ride on, so they can hit each other and rub. Not good for the parts. Oil is very important. I added a KNN racing oil filter and 5 quarts of Valvoline VR1 Racing oil. I use the VR1 racing oil for its high zinc content and special additives. I ran this in the dying small block V8 and it lasted about 5 times longer than any other oil before it deteriorated and needed changed. This stuff is tough. With the new oil in, I cranked the engine, it started, clanked a few times, then idled smoother than anything I have ever owned or seen recently. I let it circulate oil for a few minutes, then shut it down and restarted it. It started faster and easier than anything I have ever seen. I was amazed at this. No more hideous noises, no fuel leaks, nothing worrisome. The only problem I found was a slight whistling coming from the carb. I traced this to the choke flap on the top of the carb and deemed it safe to ignore.

Currently, I am unable to determine the temperature the engine is running at, but I will have access to HVAC thermometers in the morning. All that is left to do is get it up to temperature, test the temperature, then test drive it a bunch and see what happens. If the temperature tests are passed, then it will be ready for daily driving once again.

Tomorrow will the time to do a full tune up on the engine, including new plug wires,new spark plugs, vacuum advance inspection and test, and timing verification. After it is ready to run, I will be replacing the burnt old wiring harness sleeve with new, bright red convoluted tubing. All the wiring will be ran neatly, and the entire engine bay tidied up. Tomorrow should be a very productive day in deed.