Posted by Paul on Saturday, November 18, 2000 at 19:23:03:
In Reply to: 318 poor gas mileage posted by K70W100 on Saturday, November 18, 2000 at 04:40:01:
Your compression doesn't sound good. It shouldn't be that far apart on the cylinder pressures. You may have a burnt valve. Hook a vacuum gauge onto the intake and see what you're pulling. If you do have a burnt valve and have to pull the heads, go ahead and put a new timing chain set into it. You're getting to the milage where S.B. engines like to lose them.
Other things it could be is a front end out of alignment due to toe out problems or bad components, a leak in your fuel line or fuel tank, a bad rebuild on the carburetor or a combination of factors.
I had a Trailduster that I bought and the seller told me it didn't get very good gas milage. It wasn't bad after I put a different carb. on it, fixed the bad bearings in the front end, wired the cylinders up right (three were crossed) and replaced the gas tank with a hole in it.