MPG

Hey guys new to the forum! I have a 63 Ranchero with a 170, 3 in the tree. A few months ago my muffler fell off, it was kind of rusty. When it did I was getting about 21 mpg. I finally got a new muffler, actually a new 2 inch exhaust all the way back with a glass pack, single pipe. Now my millage is about 18 mpg. I thought by helping my engine get ride of air faster it would help? Any advice? Thanks!

Was the old exhaust also 2 inches? Going with a glass pack only makes it sound louder, not necessarily better. There are chambered mufflers that dampen the sound without restricting the air flow.

Getting an engine to flow better doesn't mean it will help mileage. If all it took was too get as much air as possible to flow through an engine to increase the mileage, everybody would be running 4 or 5 inch exhausts. Actually getting TOO MUCH air to flow will kill mileage and requires to carb to be re-jetted. That is why lots of racers keep records of everything they do to their engines to see where they get the best power.

If the new exhaust pipes are too straight, allowing better flow, they can and will kill mileage. Get someone who knows what they are doing to try to re-jet the carb (probably one size richer) and I bet the mileage gets back to norm.