After I pulled the 351 and installed the 250 I6 I expected my fuel economy to increase. It hasn't and I can't figure out why it's so low. I've been getting between 11 (worst) and 14 (best) mpg, mostly in town but some highway driving. I actually got better mpg with the 351 than I do with this 6. I don't drive it hard at all - more like a grampa.
I have the 250 from a 73 Maverick, a T5, a 3:1 open 8" differential. The engine was rebuilt by a reputable local shop as a stock. It's overbored slightly. I'm running a stock cam, stock lifters and the rebuilt RBS carb that came with the engine.
I have found and fixed a couple of very small fuel leaks but the mileage has not improved. I have also confirmed that the choke is opening fully when the engine has warmed.
I've checked the drag on the wheels and did find the right front caliper was stuck. I fixed that and the mpg went up from 10 to between 11 and 14. There's no unreasonable drag from the brakes, front or rear.
I was wondering if the fuel pump might be leaking internally but the oil level hasn't changed so I'm thinking that's OK, but may change the pump anyway just for giggles.
I really like the car this way but would probably stick the 351 back in it if I can't figure this out and improve the fuel economy.
Any thoughts? I'm out of ideas.
Thank you!
I have the 250 from a 73 Maverick, a T5, a 3:1 open 8" differential. The engine was rebuilt by a reputable local shop as a stock. It's overbored slightly. I'm running a stock cam, stock lifters and the rebuilt RBS carb that came with the engine.
I have found and fixed a couple of very small fuel leaks but the mileage has not improved. I have also confirmed that the choke is opening fully when the engine has warmed.
I've checked the drag on the wheels and did find the right front caliper was stuck. I fixed that and the mpg went up from 10 to between 11 and 14. There's no unreasonable drag from the brakes, front or rear.
I was wondering if the fuel pump might be leaking internally but the oil level hasn't changed so I'm thinking that's OK, but may change the pump anyway just for giggles.
I really like the car this way but would probably stick the 351 back in it if I can't figure this out and improve the fuel economy.
Any thoughts? I'm out of ideas.
Thank you!
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