Over the winter the truck hasn't been driven much, but there has been some activity. You'll love this story that played out over the last 3 or4 months:
The truck would not start, so I knew that it would either be a fuel or spark issue.
I pulled the fuel line from the carb to check that it was supplying fuel, and it was: I could crank the engine and fuel was delivered from the fuel line. I banged on the carb with a rubber hammer to see if that would un-stick a possibly stuck needle and seat, and sure enough, the truck started. Great!
But then the next day it would not start. This repeated a couple of times. I then removed the front carburetor bowl (and metering block) to check the float itself and it was moving freely and looked OK. I re-attached the bowl and metering block with the same gaskets which, looking back on it, was a mistake.
I also used a spark tester to ensure that when the truck wouldn't start, that I was at least getting spark on one cylinder, which I was. The wire connections to the HEI distributor looked OK.
I needed a new needle and seat assembly. I called Quickfuel (Holley) to help determine which model of Quickfuel carb I had because this has no numbers stamped into the air horn. After 5 minutes of discussion with their tech support, they could only determine that it's a 4150 or 4160 clone, but it didn't matter because they all use the same float needle assembly part number. Rather than dumping money into the carb for another needle and seat assembly, I cleaned this one with carb cleaner and reinstalled it. That was the Quickfuel tech's idea, which makes sense.
At this point, the engine would start fine but was not running right, probably mostly due to me having never replaced the gaskets which probably caused all manner of vacuum leaks. Removing the needle and seat assembly of course means that the fuel bowl level has to be re-adjusted. This carb has sight windows so it's fairly easy to do. Ultimately I could see fuel in the bowls and adjusting the level was possible.
I adjusted the idle air mixture screws and idle speed screws with no great improvement. The most telling sign of a problem was that a manifold vacuum gauge needle would bounce wildly, fluctuating by maybe 5 or 8 PSI. I thought this might be a sign of a broken valve spring, stuck valve, or bad rings. Uh-oh.
At the same time this was going on, it was getting more and more difficult to start the truck. I had been cranking it a lot, but the engine was not running or not running for any length of time. The battery was basically dead and would not take a charge. I finally put in a new battery and now finally I could crank the engine, however if did get the engine running, it was not happy.
Because I had never checked any of it before, I went over the ignition system. I tested all of the spark plug wires for resistance and they were all between 6.3K and 11.1K ohms each (not per foot, but the whole wire). This generally seemed in spec with what I was reading elsewhere. I removed the Delco distributor cap to get a look in there. The cap terminals looked un-worn and clean. The rotor, which is an MSD, looked fine. The wired terminals in the unit looked OK. I did not remove the rotor or go any deeper.
At this point I suspected the carburetor was my problem, because it had a possibly flakey needle and seat valve and it probably also needed love after I had removed the bowl, re-used the gasket, and jacked with the mixture and idle screws. I talked to Holley (Quickfuel) support and they recommended the "HR" (Hotrod) series carburetors. I wanted a vacuum secondary. That model doesn't have a 650 CFM with vacuum secondary, so they recommended the next larger CFM. Finally, I bit the bullet and ordered a new Quickfuel 680 (model HR-680-VS) with a vacuum secondary. JEGS had a $10 off coupon which made a lower price than Summit Racing.
The new carb at arrived last week and I got it installed yesterday: The bracket to attach 700r4 cable to the carburetor throttle assembly took a while to transfer over. The stud for the throttle cable had the wrong nut from the previous owner (1/4-20 instead of 1/4-28) which also had red Locktite on it, and the Quickfuel 680 throttle lever assembly was slightly different than the old one which meant that I didn't need one of the same spacers, but I had to get a bronze (or any material) bushing and trim it down to basically make a spacer/washer. I could not find the right parts in my bins of old fasteners. These were small problems but I did not want to cut corners. So I went to the hardware store to get the correct stainless steel nuts and the spacer. I finally got the bracket moved over to the new carb with the correct hardware. At this point I'm probably 3 hours into it.
The new carb installed OK and the throttle cable, transmission cable, vacuum lines, and choke power cable all attached OK. I used a new gasket and tightened things down according to the directions that came with the carb. I cranked the engine to fill the float bowls for 10 then 20 seconds and got... nothing.
I pulled the fuel line from the carb and, no surprise, no fuel was pumping. I was working on removing the fuel pump and first disconnected the fuel tank line from the pump. No gas ran out when the line was disconnected. This seemed bad. At this point now I'm thinking the tank is empty. Doh!! Son of a....
I put in 1 gallon of lawnmower gas and 1 gallon of gas from a neighbor. I then drove those empty cans to the nearest gas station and filled them up with 4 more gallons. I put all that into the C10 which would have given it maybe 6 gallons total. If that didn't help, then I would replace the fuel pump.
I cranked it again and finally started getting gas from the line to the carb, into an old paint can. Thank goodness. Now at least I know the tank was empty. I reconnected the fuel line to the carb and cranked the engine again. Finally, it started after a few seconds. Success at last!
Of course now I'm wondering how much grief I had because the dang tank was empty. The last time I drove it any distance, I know (or thought) I had roughly half a tank. So either I was wrong, or there was enough evaporation to lose several gallons, or there's a fuel system leak I don't know about.
Anyhow, the new Quickfuel 680 VS ran great on the first try with no absolutely tuning. My neighbor hopped in and I drove around the neighborhood. The 454 has greatly improved performance and is even speedier than before. A real demon. I stopped by the gas station again and filled it up within 10 gallons. This confirmed that yes, the tank was technically empty when I started out the day, and probably had contributed to the problems and frustrations in the last 3 months.
Now that it was warmed up, I put on a vacuum gauge and had a stable needle with no fluctuation, with about 15 PSI. That was good news and a relief to know there was no horrible valve or ring problem. I ended opening up the idle air bleeds 1/2 turn out/open and got about 1 or 2 more PSI. I tweaked the idle. That was it. I drove it around a bit more and it still ran great.
Looking back on this whole story, I had enough fuel (barely) at the beginning of all this 3 or 4 months ago, but at some point that fuel ran out and I was battling an empty fuel tank. My initial troubleshooting a few months ago confirmed I had fuel, but I didn't know how little I had to work with. I assumed it had a half tank, or a quarter tank at least.
So, I have a renewed vigor. I ordered a new factory style fuel gauge because now I've been bit twice by an empty tank which is stupid considering it's only a $50 part. Live and learn.
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