Hi guys
My c10 84 is all original, engine, carb, air cleaner...
It's like 8 gallons for 62 miles, toomuch for me.
how can i make it better?
Any tips?
( inside the air cleaner, there is a metal air filter, kinda crispy now, do i have to take it off)
thanks
So you're getting 7.75 MPG or 30.35 L/100km. That's pretty rough. Let's start with the basics. Keep a good eye on tire pressure and driving/braking habits because they will make a difference. Mechanically, the most important things that need to be executed efficiently are how your engine utilizes air, fuel, and spark. Also, how it gets rid of exhaust is important. That's with the powertrain. Power transfer is important, too. You can't have stuck calipers/draggy shoes, sloppy universal joints, or super short gearing. The two former would be worth checking just in case. You could tell if something was wrong with your brakes, and you'd hear a driveshaft clunk if the u joints were bad. I would assume your rear diff. is no more than 3.42, but your RPO sticker will tell you what's there if it hasn't been changed. You just have to decode it, and there are plenty of places on the internet that have the full library of GM RPO codes. If you're running a TH350, that'll be a hindrance, but you should still be better than you are with everything working right. Back to the powertrain concerns, let's start with air. You do need to change that filter (Walmart sells a Fram for cheap, just don't buy Fram oil filters), and make sure there aren't any vacuum leaks under the hood. Those don't help anyone, and I can't stress how important this is. The carburetor base gasket, EGR valve, and old cracked hoses are common places that leak, but cite your emissions diagram to properly go through the entire system. Make sure nothing's melted, disconnected or falling apart due to brittleness. I've used smoke to smoke out vacuum leaks, and I've used throttle body cleaner/starter fluid/carb cleaner to spray around gaskets and stuff to see if the idle changed, which would indicate a leak. Do you know if the EGR valve has been replaced recently? You can remove it, clean the carbon off the pintle, and try to push on the plunger to make sure it's not stuck. It it moves good, try pushing the plunger all the way up, capping your finger over the vacuum port, and seeing if the plunger stays in place. If it does, the valve is good. If it's a newer valve, the plunger will be mostly enclosed, so you'll have to do it with a screwdriver, but on an old one, the plunger is completely exposed. These often just leak a lot of vacuum when they're tired because they get stuck or the plunger stops sealing. Also, check the throttle shaft for play on the carburetor. I'm guessing it's a Q-Jet, and they wear the body of the carb away over time from moving so much, which that's a vacuum leak. They can have a bushing put in them so no big deal. For spark, you should probably change the plugs for sure. The cap and rotor are a close second, and I'd go ahead and freshen all that up with AC Delco parts. Unless there's evidence of arcing, corrosion, or chewing on the spark plug wires, you should be fine with those. Otherwise, replace them with the same Delco wireset. Ignition timing is important, and you should get a timing light if you don't already have one. I'd say go for 8-10* initial, and that'll help burn your gasoline more efficiently. Speaking of gasoline, fueling and metering are important. It's important to have a clean fuel tank and a good strainer sock. The fuel pump should be doing its job, and you'd be likely having some driveability problems if it wasn't. The fuel filter should be changed, too. If it's a Quadrajet, it'll be located in a little chamber inside the carb immediately behind the fuel line flare. You just have to unscrew that fitting off the carb to get at it. Be careful with the spring in there. How's the carb look? If it looks like it's on its last leg, it maybe time for a rebuild, and I can suggest two businesses that I would use for myself if you decide you need those, but I'd save that for last if you don't net the improvement you need. Exhaust is important, too. How easily your engine can expel it has bearing on economy. Factory manifolds and a brick wall for a catalytic converter are no bueno. Might be a good excuse to switch to headers and either delete the cat or install a high flow model. Speaking of which, extraneous emissions stuff like the air injection system doesn't help anything. I'm gonna delete all the AIR crap off both my vehicles at some point hopefully in the not so distant future. There are some things that can really be helped like direct or clutched mechanical fans, but they won't kill it with the other stuff doing right. Hope this helps.
