Not an economic one - although that's another fairly serious issue.

This is once again mileage-related.

Last weekend, I tried out a supposedly rebuilt B18B cylinder head. I can't tell if this did anything positive for my mileage yet, but my last fill-up was once again disappointing. 131 miles with 9.38 gallons. Damn.

After removing my 500,000 mile B18D head, which went on the engine to see if I could find anything wrong with the B18B head that was installed on the engine when I bought the car last year. Follow me?

Weather being what it is, I did not have a chance to look at the removed head(s) until this afternoon. I checked valve stem height by laying a 24" straightedge across the valve stem ends. Crude, but suggested by a fellow BBer. (Suggest a better approach if you don't like it).

The results were not wonderful.

On the B18B that came installed on the car, At least three of my valves were 1/32" or more shorter, suggesting that the other five or so were sitting higher (and therefore receded?).

The B18D head I ran with for a couple weeks was *much* worse, with gaps up to 1/16" or more and valve stems poking up all over the place. I could rock the straightedge around on the stem-tops. There's no way that's good news.

I have not checked the "rebuilt" B18B yet as it's installed and I will not have time to remove and re-set the rocker and valve lash.

Could valve recession be a major culprit in my consistently poor mileage?