Inliners International Forums General Discussion Engines Question regarding fuel milage between 292 and 250 chevy engine??

Hello I am new here, I own a 1980 Chevy G10 van and I dumped out the 350 engine that had a 4 barrel carb and replaced it with a 1988 292 with the idea of getting better gas milage closer to a what you would expect from a mini van say around 20 MPG.

Can someone tell me what I should be getting for MPG,? I have a hard time knowing for sure what its getting because my odometer is busted, its seem to be around 18 would this figure be correct.? I have a 1969 monoget one barrel carb on it with manual coke and 308 rear end hooked up to a 350 turbo non lock up transmission.
Also would like to know too what the MPG difference is in running say a 1964 rodchester B carb compared to the newer monojet I have on there now.?

I also want to know what the differce is in MPG running a 250 in my van compared to a 292 if someone knows.? I much prefere the 292 but everyone I talked to say the 292 is very bad on fuel I dont know if there is a big differnce or not between the two engines in my Van aplication, I do know that the 292 was very rare to find in G vans I dont know why GM prefered to put 250 engines in vans more between 1971 and 1984.

I notice that since the gas price hike that there have been hardly any 292s show up on E-bay for sale.

Because of not knowing your driving style, weight of your vehicle, or the aerodynamics involved, it'd be difficult to predict your mileage. However, a while back, a friend had a mildly modified 292/ 3-speed OD with a 3:73 rear end, in a '50 chevy 1/2 ton pickup. He was averaging about 17 mpg on the road. When he badly over-reved it one time, it threw a rod. Then, he replaced the 292 with with a 250, using the same intake and headers, transmission and rear end. His mileage went to about 20 mpg on the road, but he didn't have the low-end torque as before. My stock '65 Chevy pickup with a 250 would get about 17 mpg, on the road, with the standard 3-speed tranny. Don't remember what rear gears I had, though. Maybe this will give you a ball-park figure.

IMO you will get better mileage with a 350 than a 292. I would be surprised if you can get 18MPG out of a 292, especially with a turbo 350.

If you're getting 18, that sounds pretty good for your vehicle. I had a 1936 Dodge sedan with a 250 and it got 20 mpg with a 200-4r auto OD and a 3.00 rear end. I put a 292 in it and it went to 18. I don't think you can do much better than you are. Joe