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Initial State, Initial Engine Dyno Tuning (350 sbc)

The Corvette came to me in very rough shape. Despite having had a myriad of extended family friends swear the Corvette was worth 40,000 dollars, the Corvette didn't even want to run. With some work and tinkering, we were able to get it to barely scoot along. Replacing the spark plugs introduced major concern, as one of the ceramic centers had been blown out. Those are very hard and thick pieces, and don't just dissappear. Something was woefully wrong. Ontop of that, 10 years of squirrels and mice had moved in and out of the Corvette. It was in rough shape, and needed a lot of attention.

The first thing I knew to do with a vehicle like this, was to check the basics for an engine to run. Compression, Fuel, Spark. I needed a shop that could check the engines compression, then get the fuel mixture dialed accross the RPM's and ignition correctly set. This required a compotent shop with access to a dyno. I turned to the team at Granite State Dyno. They had a demonstrated history of working on powerful vehicles, they had a dyno... they would be able to get the job done right.

The Corvette came back from compression testing decently. Most cylinders were at 215, while one was at 185. While notably low, it wasn't beyond functioning and within the realm of running. They tossed the Corvette on the dyno and began to attempt to sort the engine out, and quickly hit a wall. Finally out of sheer frustration they pulled the carb my father had on the Corvette off, and tossed on borrowed carb. Sure enough, the car began to idle like a honda and ran great. The Carb was the primary culprit of so many issues. Further investigation yielded the carb had a hairline crack, that as the carb heated expanded creating an air leak playing hell with the idle circuit and in general causing fueling issues. It was exactly the kind of issue my father would never find, especially as he would never outright replace anything. He used to take apart alternators and replace $.02 diodes... even if the alternator failed again when the next diode went bad in a week.

With a new Holley 4150 650cfm carb in place, the Corvette was running pretty solid. Unfortunately, this is where the continuing story of how unsorted the Corvette was continues.

The Corvette had high enough compression it required a mixture of high octane pump gas and leaded race fuel. Running a 50/50 mixture of the two yielded reasonable results, but the Corvette was still insanely doggy for the ungodly high cost of fuel this yielded. Pushing only 254hp and 281ft/lb of torque, the Corvette was surely not taking full advantage of the costly race fuel I had to put in. The shop had some observations of their own. The heads were old iron heads, nothing amazing. The intake was ultra aggressive, the cam was not. The whole thing appeared cobbled together, and needed review.

You can also see the giant bog in the dyno sheet from where they jump on the throttle, the car starves for fuel, and then shoots off as it catches back up. The aggressive intake manifold couldn't be sorted enough with the accelerator pumps to remove the bog. The corvette now ran... but had just been downgraded from barely running nightmare to giant logistical challenge.

At nearly $1 a mile to drive with the race fuel and high octane pump gas combo, the car just seemed silly. Something was still not sorted... and let's not even get into the logistical nightmare of finding gasoline if I ever wanted to take this car on a trip somewhere.

Thus began the investigation into the engine... that lead to a whole new engine.