Thread: 283 with small journal 327 crank

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Roland I believe you are thinking of the a 283 crank in a 327 block which yields the "302"

The other way around..... a standard bore 283 with a 327 crank yields 306.624 (307).

Although I have never done this stroker build I have run a few slightly modified 307s, they produce torque but do not wind up.

Personally I would not expect a huge mileage gain with the 307 maybe 3 or 4 MPG.

I would take a guess and say that your current gas mileage is affected by 2 areas.... wind resistance (trucks have aerodynamics of a brick) and RPM. While you can't do much about the shape of the truck a gear change or addition of an overdrive would likely give you as good or better mileage than the small block swap.

I’m sure what the interstate speeds are there but at 75 MPH and assuming a 31 inch tall tire what ever engine you run would be at 3032 RPM (plus a little bit for converter slippage).

Changing to a 3.08 would drop the RPM to 2500, and leaving the 3.73 gears and installing a 700R4 would drop the RPM to around 2100 RPM.

Unless you already have other plans for the 454 the 700R4 swap would be the way I would go. I believe it would give the biggest mileage gain and still be cheaper and easier than an engine build and swap.

Guys, Well what could I have been thinking !!! DUUUUUH That was one of those embarassing senior moments. DAMN

Of course ----And I stand corrected----- I was referring to the 327 4" Block and the 3" 283 Crank........

Roland