Before the small-block Chevy appeared…

There is a specific reason for discussing this period before the game-changing small-block Chevrolet arrived on the scene.  (Primarily, there is a lesson to be learned for the contemporary performance enthusiast or engine builder.)  It was a time when the platform for configuring a high performance street or racing engine was founded on the modification of an otherwise stock production engine.  You either opted for a large displacement stock engine and dressed it with a non-production camshaft, induction and exhaust system for street use or dug further into machining and related modifications that took power to the next level, based on applicable racing class rules.

There were no specially designed aftermarket cylinder heads or blocks, no purpose-built oiling systems or other such components available, and particular emphasis was placed on the ingenuity of the builder.  Part of the reason for this stemmed from the relative infancy of the overall motorsports community, combined with an equally maturing specialty aftermarket parts industry.  The latter of these two was still emerging from the creative juices and pent-up testosterone found in returnees of WWII, many of whom were or would eventually become the foundation of the current high performance industry.   Citing specific examples of them would serve no purpose here, save the fact that they were providing a creative path being followed by hot rodding enthusiasts throughout the U.S.  Hot rodders knew what they wanted to do and parts providers were enabling dreams to become realities, the glue for which resided in the heads of enthusiasts geared to thinking.  Here is a case in point, based on personal experience.

Just a few years before Chevrolet introduced its then-revolutionary small-block V8, it was the norm to install either an Olds or Cadillac engine in cars of lighter weight.  Despite the fact both engines were sufficiently heavy to create related suspension and driveability problems, particularly over-steer, they produced healthy measures of torque based primarily on piston displacement.  Personally, I wanted something different that didn’t overburden a stock suspension system but recognized the value of increased torque.  I’ve long been of the school that good street performance equates with a solid, broad torque curve.  I also didn’t have much money.

Since so-called “junk yards” were the source for most engine swap materials, I began my search.  Not surprisingly, there were far more in-line 6-cylinder engines available than the large V8s.  I then expanded my “research” to see what V8-alternatives might be worthwhile.  Long story short, I finally settled on seeing what might be done with a 270-inch GMC 6-banger.  Within the small group of rodders to which I belonged, two of us had early ‘50s Chevy coupes; one a ’50 and mine a ’52.  Collectively, we decided to “build” a 270 for the ’50 coupe and use it as our guinea pig.  Reckoning that it’d need multiple carburetion, an aftermarket cam and dual exhaust system, we discovered a small California-based company that seemed to specialize in GMC 6-cylinder performance parts.  Because we were replacing a 6-cylinder stock Chevrolet engine with another 6-cylinder GMC version, the installation was relatively simple.  Nobody considered whether the stock 3-speed manual transmission was sufficient for the rather substantial increase in low- and mid-rpm torque.  Turns out it wasn’t.   Actually, we were in uncharted waters since nobody in our area had ever even considered such a swap. 

But I’ll tell you something.  Once we’d cured the transmission ails and sorted out the carburetion, the package was a stoplight bandit.  Of course, the stock 4.10:1 rear gears didn’t hurt our efforts and problems with over-steer were non-existent.  Plus, we had something nobody else tried.  Next, it was my turn, having seen the relative ease of installation and success of our 270 effort.

Did we carbon copy the project in my ’52?  Certainly not.  I mean, if a 270 successfully met our goals, what more could be gained by starting with the larger 302?  They were just as plentiful in used form and would accept an over-bore of 0.125-inch, raising its displacement to a then whopping 320 inches.  There was also another caveat we uncovered.  The same company we’d previously identified building street performance parts for the GMC 6 also had components for short-track racing.  Bottom line, the “Jimmy” we installed in my ’52 Business Coupe wound up with a short-track cam, 11:0 mechanical compression ratio, five 2V Stromberg carburetors and a dual exhaust.  I also did some amateur porting work on the cylinder head.  Pump gas of the day would support this level of cylinder pressure.  The car also had stock 4.10:1 gears.