On the engine dyno, the 331...
On the engine dyno, the 331 pulled perfectly to 6,000 rpm. It seems as though our engine misfire is solved.
Compared with the EFI setup, peak power and torque weren't remarkably different. Horsepower was within 5 ponies and torque was better with the carburetor by about 15 lb-ft at peak output. Where the carbureted setup made the biggest difference is average torque. At 3,000 rpm, the carburetor was ahead of the EFI by 14.5 lb-ft and it carried that advantage until about 5,200 rpm. The numbers about evened out between 5,200 and 6,000 rpm.
The most important result of the test, however, is that we found out that there isn't anything mechanically wrong with the engine. Our previous misfire must then be caused by an errant fuel injector or a bad wiring harness. Since the harness is new and the injectors are used, we're leaning towards the squirters. We sent them off to Trick Flow for evaluation and are currently awaiting the results.
Having spent three solid days on Horsepower By Hedrick's engine dyno, we think it's time to pull the Competition Products/Trick Flow 331 small-block off the rig, and get busy stuffing it in a car and putting it on the chassis dyno. In our next installment, we should have the misfire sorted out, and hopefully will have some track times to go with all of the dyno numbers. See you then.