4 Answers »

1. Hey You on November 6th, 2009 at 2:12 am:

   it all depends, auto or stick, original4300D carburetor. ford rated this motor hp very low 240hp the 73 has an egr plate under the carb,but since this is cleveland in a mach1 the hp is a little under 300hp there is no such thing as fuel economy W/this motor, ford brought the engineer of the chevy 350/350hp to ford in the 70s so they could have a more competitive edge, before the cleveland, all they had was Windsor that didn’t put out much hp, so this chevy engineer designed the Cleveland motor a mid size motor, w/ all the big block features, 4 bolt mains, and the largest heads on any 351, canted valves, in fact the intake&exhaust valves are the same size used on chevy 454s, these motor put out lots of torque&horsepower, Holman Moody use them in the italian Donzi boats, these motor put out hp at lower rpms which made them great for boats

2. 007 on November 6th, 2009 at 2:17 am:

   9-12 MPG city 14-15MPG highway. I had a 1972 that was quite powerful but at a price.You need to burn a lot of gas to go that fast.If the car is in good condition enjoy it and forget about the gas mileage.

3. Robert on November 6th, 2009 at 2:43 am:

   When I retired from the Navy 32 years ago, I had a 1970 Mercury Cougar XR-7, with the 351C with the rochester 2 barrel. It’s “stock” horsepower was 300, and I believe it’s compression ratio was 11:1.
   I ran a Holly 650 with an Edlebrock Performer Intake, mild cam, and custom exhaust. My power was “high end”. When I hit passing gear, there was nothing on the road that could touch me. And I mean that truly.
   Your 73 was caught in the early years of unleaded gas and low compression engines. However, you are not hurt too badly. You probably have the 264HP Cleveland.
   There are some Corvettes out there that only have 180HP. They were caught in the low compression, unleaded gas early years, but later than yours.

4. Joe on November 6th, 2009 at 3:25 am:

   I have a 351 ’70 Mach 1 with a lot less emission controls that gets 14-16 mpg overall. I suspect the ’73 to be somewhat less.
   Anyways – fuel economy shouldn’t be a priority on classic muscle cars such as these.

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