The Q motor series represents some very sweet running small block Chevys. Everything from the 283 up through the 350 represent essentially the same block.
Naturally there are some internal changes over the years, but it's quite hard to tell these engines from one another simply by looking at the blocks, because they're externally the same.
Here are some comparisons with the early series of Chevy SBC motors.
283F
185 hp at 4000 RPM
261 ft. lbs. torque at 3000 RPM
Bore 3-7/8"
Stroke 3"
Compression ratio 8.0:1
327F
210 hp at 4000 RPM
302 ft. lbs. torque at 2600 RPM
Bore 4"
Stroke 3-1/4"
Compression ratio 8.0:1
307Q
200 hp at 4000 RPM
280 ft. lbs. torque at 3100 RPM
Bore 3-7/8"
Stroke 3-1/4"
Compression ratio 8.1:1
350Q
235 hp at 4000 RPM
330 ft. lbs. torque at 3100 RPM
Bore 4.00"
Stroke 3.5"
Compression ratio 8.8:1
The interesting thing about the 307Q, is it's an ever so slightly stroked 283 with a hint of a compression boost. The result of this, along with some improvements in the intake design, produce an additional 15 hp and 21 footpounds of torque over the highly thought of 283.
The 350Q is rated at a relaxed 235 hp and produces a healthy torque rating. These engines are built to last, and a 350 can produce 350-hp with ease, but it probably wouldn't last as long in the marine environment as the one Chris Craft specified.
What a great line of small V8 options. I have two 327 motors right now, one that is semi hot rodded in a 17' wood Chris Craft at around 300-hp, and another in my recently acquired 20' fiberglass Sea Skiff, which has 8.5:1 compression because it's an automotive block conversion. Automotive horsepower rating of this motor was 250, and it is not known what sort of power it produces in it's present form. Performance runs may help estimate this later when we see what kind of prop it will spin. They're all able to be interchanged, with some attention to the rear seals and some other details.
One important internal change that occurred with the advent of the 350 is the 4-bolt main bearing caps. The 327 series didn't have the 4-bolt mains, and it is not known at this time whether or not the contemporary 307Q also got the 4-bolt mains when this feature was added to the 350. The feature isn't really needed in our use of this engine series, but it just makes a good engine better.
Below: The first 283 small block Chevy motor used in a Chris Craft, circa 1959, one beautiful running compact V8 motor.
Regards,
Paul
In case you haven't seen (and heard) it elsewhere, here is what a 327F sounds like at idle (turn up your speakers and ENJOY ! )
