noob needs help with mileage - only 10 MPG!

rmchrgr,

What my mechanic had to say was very similar to what you wrote above.
He said that the high leak down percentages are probably due to worn rings and/or valves, but that he can't be sure without taking the head off. He said that worst case I'd be looking at about $2,000 for an engine rebuild/reman.
Does that sound like a reasonable figure?

And the idling rough when warm thing, maybe "idling rough" is not the best way to describe what it is doing. From a cold start the engine sounds fine when idling or revving. When the engine warms up it makes a sound like engine knock when indling, but not when revving. When I picked it up from the shop where I had the work done I started the car and left it idling in park while I talked to the mechanic. Sure enough, once the engine warmed up it started making that engine knock sound. The mechanic had just explained to me that the high leak down percentages were probably due to worn rings or valves, and he also said that worn rings, once the engine warmed up, could explain the knocking-like sound.

To those of you work on engines, does that make sense?

Captain Easy,

Why is it that you recommend the Carter carb over the Holley 1920 that I have now?

As a serious noob, I'm grateful for all the input here.
Thanks, guys.