need carb and gas mileage help

Hi i have an edelbrock 600cfm carb and i was wondering how you can ajust the fuel mixture so it has about a a/f mixture of about 15:1. Do you ajust the idel screws in the front or is it something else. And also what is the difference between the right and left idel screws. also i need lots of help getting this thing to get better gas mileage. Dose anyone know what i can do to help the gas mileage like ajust the timeing or anything. I am moving to colorado from nevada soon and i want my truck to get a little more than 6 mpg. I will do anything short of putting mothballs in my gastank. Please help. Here are some specs on my truck.

78 scottsdale10 Chevy 350 with competion cam, edelbrock intake manifold, edelbrock 600 cfm carb. 6" lift w/ 35" tires on 15 inch rims. Brand new stock th350 tranny. Delco Remy distributor. PLEASE i need to save some money on a 700 mile drive please help

Sounds like you built a gas-guzzler engine there. Big cams always drink a lot of gas, that's how they produce more power.

Do you have access to an A/F ratio meter? If you have a buddy in the inspection business (depending on your state) he might have a wide-band O2 sensor that he could stick up the pipe while you experiment with different jetting in the carb. Holleys are easy to tune just by switching jets around. I think your carb uses different metering rods to affect changes in the A/F ratio. It's kind of a pain to adjust, but sounds like you need to do it.

Another thing to check, which may end up producing the best results, is the timing. With an engine like yours, I always like to use a standard HEI distributor with vacumm advance. I usually set base timing at idle (vacuum advance disconnected) at about 10 degrees advanced. Then I connect the vacuum advance line to a port on the carb that has full vacuum, even at idle. That way you will get about a 20 degree advance in timing at idle and this will really help smooth things out. Also, you will get significant timing advance under normal driving, which will really help mileage. Just make sure that the vacuum advance decreases under heavy load, or you will hear heavy pinging and could damage the engine. You can check this by using a timing light: watch timing and hold carb (by hand) at about 1500 rpm, then give it abrupt throttle and you should see timing decrease as vacuum lowers. If not, then select a different port on the carb.

Well unfortunatly i dont really have any money for a new dis. But i will mess with the timeing. I has it set at about 8' for the summer and i was thinkin that i might time it to about 12' that should give it a little more mpg, or fuck up my plugs or something dunno. And my neighbor builds street rods so he is tuning my carb for me to get the a/f back up.

Also i herd that if you run lead supliment in your gas it will take up your mpg?????

I'll bet you can find a buddy who has one kicking around. Perhaps you can score it for zero. Alternatively, you could look in a auto salvage yard and perhaps find one there. I have bought many out of junkers for about $20 each. This is not necessary if your present distributor has vacuum advance already, make sure it's working and use it. I am just saying that vacuum advance will help you gain a lot of gas mileage.