My 77 pickup has a 20r with a 22r cylinder head. It's getting 16 mpg but I've read that these babies should get somewhere from 24 to 30 mpg. What do you think is causing me to lose this much mileage? I got a new carburetor on it so Im wondering if it the way the fuel mixture is set.. and also someone wanted to say it was the radiator fluid leaking into the motor through the head gasket.. I have no idea. I've driven the thing for about 1000 miles now I thought it was just cus the carb was brand new... any ideas?

 

There are so many things...

If the head gasket is leaking, there really isn't much point in doing anything else until you fix that. It's a major issue, and if you can't do the work yourself, a major expense. And a ticking time bomb, ready to kill your engine.

Aside from that, the best thing to always do when you get a new vehicle, is:

new spark plugs, wires, distributer cap, rotor.
new fuel filter.
change all fluids.
check the timing.
adjust the valves.
tune the carb.

Is the carb a Weber or Aisin?

Check to make sure the brakes aren't dragging. Check to make sure the wheel bearings are good.

Get the compression checked.

But you read right. My 78 has a camper sitting on the back of it, and I get better than 16mpg most of the time.

 

Ditto on all that above but on the brakes if you're on almost level ground (very slight grade) the truck should roll from a dead stop slowly. Make sure the carb choke is opening all the way at temp. might have a vacuum leak also. what else guys....

I've heard 2 wd get about 4-8 mpg better than 4x4's and the best i get is about 20mpg @ 60mph, usually around 18 average city and hills.

Are you figuring mileage correctly and good tire pressure makes a slight diff.? driving habits, led foot, high speeds?

On the gasket if you dont see white smoke from the tail pipe you might be ok? I have a leak from the gasket to outside and pretty much stopped it with a sealer, the clear bottle with copper looking stuff inside. treated it two or three times in 10 years. also sometimes if you put your hand over the tail pipe and smell your palm, if its leaking can smell the anti-freeze.

 

My 76 averaged 22-24 in town, 28+ on the freeway for baseline numbers.

If you have a Weber follow their tuning instructions. Your ignition timing should be in the 8-12 initial advance range. Is your vacuum advance hooked up and working? This is likely a tuning issue. 16mpg is what I get out of my 4x4, and often better.

There are other things that may contribute but start small and K. I. S. S.

 

Thanks everyone, this is all very helpful information. I'm not sure what the manufacturer of the carb is but I can find out and look into tuning it properly. I'm getting the head gasket fixed now. Yes it's a major expense but its for my yota I'll have to try all these ideas thanks again!

 

If head gasket is done by you or shop be sure the head surface is checked for flatness, probably will need a slight flycut but be sure to insist on removing minimum metal amount needed to be flat. U might know but If head is not flat you'll blow the gasket again before long.

 

the carburetor that was on there was a k267 or something (I forgot what he called it). It wasn't agreeing with the truck. after going through trying to make it work for the longest time my new mechanic said he was gonna get a weber and that'll fix all these problems it's been having with running. I'm happy to hear that it's gonna be running, but I wish the other mechanic knew it needed a weber before he charged me for the first carb that doesn't work

 

I'll be interested to hear how it works out.

No such thing as "needing a Weber", but that doesn't mean it won't fix the problems.