High RPMs and bad gas mileage

[scottgowin]

I purchased a 78 spider to use as a commuter car thinking it would get better gas mileage than my Dodge RAM 1500 Hemi. Unfortunately this spider appears to be a gas hog. I am concerned that the RPMs remain high at freeway speeds (3,000-3,500). Maybe this normal gas mileage and/or RPMs at freeway speed. Any suggestions?

[azruss]

RPMs are normal for a spider at highway speeds. should be getting in the 25mpg range.

[Zippy]

There are many things that can cause a Spider to be a gas hog but high RPMs are not it. My 78 spider runs about 4000 RPM at 70 MPH and on a trip from Seattle to Portland I would get about 28-29 MPG. More than likely there is a problem with your carburetor. Do you smell unburned gas when you are idling? How is your compression?

[scottgowin]

I had the carb checked by a mechanic for an unrelated problem. How do you check the compression? Is this something a novice can do or do I need another mechanic?