I bought a J. Mummert's alternator bracket and it's great but I had to put a shorter v-belt on due to the belt rubbing on the bracket.

My question is , will a shorter belt change the timing. My gas mileage has decreased and I'm looking for the cause. I went from 14-16 mpg to 9 and it seems to be running richer and also I have a black carbon smoke from the exhaust on start up and I had corrected that with a newly rebuilt teapot 4000 carb.

Claim to fame is the car was used as an extra in the movie Diner with Micky Rourke, Steve Gootenburg, Paul Riser and Kevin Bacon.