Going from 20 mpg to 16 mpg IS a big difference...20 percent.

Be sure everything is properly hooked up, including the throttle-to-EGR
valve, and to specs.

Check your plugs. Do they show evidence of a too-rich mixture?

If you're taking a cross country trip, and going through mountains too, you
will be cursing that "not a big difference".

----------
> From: Dale Hartman <zeldah@PRAIRIE.LAKES.COM>
> To: vanagon@GERRY.VANAGON.COM
> Subject: Gas Mileage
> Date: Sunday, June 11, 2000 4:19 PM
>
> I have recently put in a new engine, one of Boston Bob's, and I seem to
be
> getting less gas mileage than I did before the conversion.  It seems I'm
> getting about 16 miles per gallon, whereas before it was closer to 20.
Not
> a big difference, but it also seems that my gas gauge is not working the
> same as before either.