1990 civic wagon fuel economy

I recently blew a head gasket in my 1990 civic wagon, and after
replacing the gasket and re-machining the head, along with changing the
belts and adjusting the timing i'm back on the road.

the troubling thing is that my fuel economy was nothing special to
begin with (26mpg), but after the repairs it has dropped to 18mpg! any
ideas on what could be causing this and how to fix it?

 

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If you had to reset your timing by about 8 degrees, your timing belt is
probably out a tooth, so you've corrected the ignition timing the other
way, now there's two mistakes.

Possible? 'Curly'