One would think that in 1955 Chevy engineers
would have been on top of the world. They had
just released the new 265 cubic inch V-8 and
the buying public loved it.
But even then they knew a bigger, more powerful
engine would be needed to power future trucks
and cars. So when company heads gave them the go
ahead, the engineers developed another famous
motor. The “W” block.
The 348 cubic inch “Turbo-Thrust” motor debuted
in 1958 and things were never the same. Where the
283 block decks were 90 degrees to the crankshaft,
the 348 was 74 degrees. This in effect made it a
The 348 was originally designed as a truck
motor and was 1.7 inches longer than the 265,
3 inches wider, and 1 inch shorter due to a
flat intake manifold.
The new motor had bigger valves, a bigger
bore, a longer stroke, and the potential to
be bored a lot larger with higher compression
Two versions were available in 1958. One had
a single four-barrel carburetor and the other
Chevy came out with the posi-traction rear
end in 1958 also, being the only one on the
market at the time. The combination gave the
bowtie guys the edge at the track.
These torque monsters did have a weak spot,
the piston and wrist pin assembly weighed in
at 1.5 pounds. That is a lot of weight to
move around at high RPM.
In late 1958 the police-package 348s went
on sale with 315 hp and the tripower version
got kicked up to 300 hp.
In 1961 the horsepower went to 350 before
the release of the 409 with 360 horsepower.
1962 saw the horsepower jump again to 409
horsepower while a few racers were using
Z-11 equipped Chevys.
In 1963 the 425 horsepower versions hit the
streets and 409 sales hit 21,267.
In 1964 racers bored and stroked the Z-11
to 427 cubic inches until in mid 1965 the
409 was discontinued in favor of the 396.
If you owned, or raced, one of these cars
you know the potential they had.
Comments are always welcome.