i need to know how to tune my car for mileage. 302 v8 74. i was messing with the carb and got it rebuilt. and recently fixed my gas tank float. i was getting around 200 miles on a tank before working under the hood. and now i get around 75 miles on a tank. what the hell did i do wrong?????? i recently got a dwell meter so if someone can tell me what to do i would really love it.
Do you have two vacuum lines going to the distributor? If so, they might be hooked up on the wrong port. Swap them around and see if it helps.
usually a header/intake/cam will have a huge impact on power and will help out on mpgs. If you want major millage swap to a five speed. Its a big project though.
If you have that much of increase in gas consumption, it could be going into you oil pan. Better pull the dipstick and see if it has a gas odor. You can also burn what's on the dipstick if it does have gasoline.
Hole in the tank or a line? I had a rubber line split just enough it leaked, but you didn't notice any gas on the ground. Check for wet spots.....
if all you did was the carb rebuld and the gas tank float, then most likely the carb is the problem. unless you are driving alot more agressive than you were before. pull out a spark plug and post a pic of it.
. could be a fuel pump gone bad .. ruptured diaphram and is as ol maverick said going into oil pan, is oil overfull now? smell it and see if it smells like fuel. check all lines from carb back to tank. what about float setting? could be to high.the choke is it opening correctly? pull plugs and look at them. are they gas fouled? you said motor was missing badly before build , is it still? miss fireing can burn fuel up in a hurry well not burn but use it up. check these things and what others have said . hope you find your prob and correct it.
Make sure your power valve is installed correctly. Do not use pliers on it as it may warp the housing and rip the diaphragm. Use a 12pt socket that will slip over it,make sure you have used the thick seal,they're usually reddish in color,and don't overtighten it. Snug will work fine. The threads in the carb body strip out fairly easily. You don't want to do that! If this part is bad,you will use lots of fuel and you will see no leaks. Check what previous posters said about fuel in the oil,as this is quite bad for your engine. It would be a good idea to change your oil + filter anyway,after your fuel problem is fixed!
When you finished the carb, did you put a vacuum gauge on the manifold vacuum port and adjust the idle screws for max vacuum? If not, do that. But first, make sure the float is adjusted correctly. If not, it will overfill the bowl and leak into the engine...bad gas mileage and a very rich running engine will result. The vacuum should be about 20inches and the car should smooth out when it is good. Then, make sure the timing is correct. Good luck,
also would disconnecting the pollution control and that stuff and by passing all of that effect the mpg
