Pontiac Firebird SD-455 Engine - New-Age Super Duty

Coming off the trailer, the T/A sounded tough, and it was hard to believe you could actually go to a dealership and order a new car with this internal combustion music emanating from the tailpipes. Strapped on the dyno, as was usual, we all took a guess at what the power would be. Since it was a complete stock rebuild except for the addition of an R/A-IV-spec cam and was factory-rated at 290 hp at the flywheel, anything north of 232 hp at the ground would suggest better than stock power output. This was based on a driveline loss of around 20 percent. It would be interesting to see if the cam choice increased power substantially.

After a few part-throttle warm-up runs, the first full pull was made. Ida's computer showed 253 hp or about 304 ponies at the crankshaft. Not bad: a little more than Pontiac rated the engine for in 1974. Since it's proper dyno-test procedure to do at least three runs to collect accurate data, we were on the way to Run 2. With Melvin at the wheel and Bob on the dyno controls, the Pontiac proved a worthy performer with exactly the same numbers. After a brief cooldown for repeatability, we all believed that one more run would provide an accurate baseline for our test. About halfway through Run 3, a severe rod knock surfaced and the test was aborted to prevent hurting the engine. With disgust, Melvin calmly said, "Here we go again."

Doing It Right
I don't know if the number three has any significance to this Firebird. It blew up on the third dyno pull and now needs to be rebuilt for the third time. But we can say with confidence that the bad engine luck ended when the 455 was delivered to Bob and Craig Wise of RaceKrafters Automotive Machine in Lancaster, Pennsylvania. No stranger to the pages of HPP or Pontiac engines, the Wise brothers not only know how to make power with a Pontiac, they know how to make it last.

Upon disassembly and inspection, it was realized that the so-called machine shop was not worthy to rebuild a lawn mower let alone a rare and honorable Super Duty. Mickey Mouse machine procedures, a lack of measuring, and no concern for attention to detail was a sure recipe for catastrophic engine failure. After Bob pulled the engine down, he was surprised it had lasted 250 miles and two dyno pulls. Though many new parts were going to be required, there wasn't much there that couldn't be fixed by the skills of the crew at RaceKrafters.

If there is any message to take home here, it is that when doing engine work, there are no corners that can be cut or places to save money. In Melvin's case, he was not interested in trying to do the job on the cheap; he was a victim of a machine shop that could talk the talk but not walk the walk. For this reason, Part I of the series is dedicated to understanding the necessary procedures to properly rebuild a Pontiac engine.

All too often, a rebuild consists of a quick hone job with new rings and bearings. That may be fine in some cases, but that can only be determined after a complete teardown and measuring session. The problem with doing it right is that the initial cost is substantially more than a ring-and-bearing job. But, in the long run, it's always more economical to do any job right the first time instead of doing it over again.

Since the story is best told with pictures, follow along as HPP and RaceKrafters do this SD-455 proud. Please note: All specifications, blueprint data, and parts identification will be revealed in Part II.