73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Performance => Topic started by: pedigo78 on May 26, 2011, 10:27:38 am
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I have a 85 chevy with a 454. I need to get the carb tuned so that it runs better. I put gas in my tank at 23 miles on the odometer. I fill it back up at about 86 on the odometer. That is bad real bad. I know that it is running rich due to the rich smell, black smoke when punching it, and the occasional backfire, also the occaisonal stall when i turn the engine off.
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I would guess that at a minimum you should be able to get 10 mpg, depending on many variables. Lots of members here are reporting 15 or better with their 454's. What carb do you have on it, and how is the condition of everything as far as tune-up parts? You can lean out your mixture at the carb pretty easily, but you may need to re-jet, etc. to get it perfect. Make sure your timing is dialed in, lean out your fuel mixture and make sure to clean or replace your plugs. After running rich for an extended time they are probably looking pretty nasty.
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how many gal did you put in cause if your getting only 3mil to the gal you probably have a leak or you odometer is working right.
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I have some trouble believing 15+ mpg from those pigs unless someone is sharp & made some improvements geared toward mileage increases, in the stock form in our trucks, nah. 9-11 is what I've seen/hear. Now the 3-4 your getting...something is wrong here. Either your gallons, math, someone stole it, it's leaking...something! Running rich isn't making it THAT bad. Check it again if it really bothers you. Lorne
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I have some trouble believing 15+ mpg from those pigs unless someone is sharp & made some improvements geared toward mileage increases, in the stock form in our trucks, nah. 9-11 is what I've seen/hear. Now the 3-4 your getting...something is wrong here. Either your gallons, math, someone stole it, it's leaking...something! Running rich isn't making it THAT bad. Check it again if it really bothers you. Lorne
I've gotten 15.8 mpg traveling 60 mph on the interstate with my 454 C20 4 speed with the 3.21 gear out back so it is possible. Bone stock with 127K miles and all the emission controls still on the truck.
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Well I may be I dont have a leak, and the personally think the carb is completely wrong set up. To bad I dont know enough about carbs to tune it or put the right carb on it. The motor is solid and runs smooth at all speeds. I must drive with a light foot at all times, cant put a lot of fuel to it at once or it will stall and then take off. Now with a steady increase on the pedal it runs nice and smooth. I dont know, to tell the truth I am little fruastrated
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if its running too rich you wouldn’t even see that mileage unless it would be pouring into the carb then you wouldn’t even be running it would die and be flooded the only thing I can think of really is the odom is off or something else is
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Any idea what carb you have on there? It shouldn't be much more than 700-750 cfm and even that is a bit much. I've run a 650 Edlebrock on a 454 and got about 12 in it
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I've gotten 15.8 mpg traveling 60 mph on the interstate with my 454 C20 4 speed with the 3.21 gear out back so it is possible. Bone stock with 127K miles and all the emission controls still on the truck.
Well hush my mouth ;)...I would concider you a credible source & if one would, I could easily see it being the one you describe...non 1-ton with pretty much highway gears, manual trans. in a flat part of the country. Good Deal! Zieg, What does it get around town being used as a normal vehicle? Lorne
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I've gotten 12 miles per gallon with mine, mostly driving around town, I hauled our 2300 lb camper on May long and I'm scared to see what it was.
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I've gotten 15.8 mpg traveling 60 mph on the interstate with my 454 C20 4 speed with the 3.21 gear out back so it is possible. Bone stock with 127K miles and all the emission controls still on the truck.
Well hush my mouth ;)...I would concider you a credible source & if one would, I could easily see it being the one you describe...non 1-ton with pretty much highway gears, manual trans. in a flat part of the country. Good Deal! Zieg, What does it get around town being used as a normal vehicle? Lorne
With the carb needing a rebuild because of starting issues and the fuel-air mixture screws still plugged I get a solid 13 country driving. Pulling a car trailer it drops to 11.
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I once got 13.8 steady 60mph,A/C off, flat country, all highway. I have 3.73s, th400, and all stock w/ a quadrajet needing repair. When I towed my 40' 12,000lb bumper pull camper I got 5-6, not bad. Reckon ethanol free gasoline makes a difference on these rigs? I know it makes about a 10% difference on my 01 Toyota 4.7
edit: 13.8, just checked my book