THEN YOU LOSE SOME

"A Tribute to Jim Wangers' 1964 GTO 'Test Car' built for Car and Driver March 1964"

CHAPTER 7 Greg Raymond

With the engine reassembled and JBA’s Stage II High‑Performance Package fully balanced and installed, we headed back to the dyno at JBA Speed Shop for another round of testing. Expectations were high. The numbers looked promising… until they didn’t.

The Advantage of Experience

When you’re surrounded by a team of high‑performance engineers with more than 50 years of combined engine‑building experience, you gain something invaluable: the ability to spot trouble before it becomes catastrophe. Their instincts, sharpened by decades of Pontiac knowledge, allow them to catch the smallest inconsistencies—details most people would never notice. That expertise proved essential.

A Lean Idle and a Troubled Center Carb

As the 389ci Tri‑Power warmed up, two issues surfaced. The first was a lean idle condition. It didn’t take long for the team to trace the problem to the center carburetor. We made a few cautious pulls, but no amount of adjustment could correct the lean condition. The decision was made to stop for the day and pull the carb.

Once disassembled, the problem became obvious. The baseplate gasket between the throttle body and main body wasn’t sealing, and both idle mixture screws had zero effect on the air‑fuel ratio. Fortunately, with help from fellow Pontiac club member Jim Thomson, we located a complete 1966 center carburetor on eBay.

Just like that, we were back in business.

The replacement carb worked flawlessly after a simple jet change. The roar of the 389 filled the shop, exactly the sound we’d been waiting for.

But There Was a Second Issue…

Even with the carburetion sorted, JBA’s chief engineer John Elderhorst noticed something subtle: a faint hint of blow‑by. Most people would have missed it entirely. John didn’t. His perfectionism is one of the reasons this build is what it is.

He ordered a leak‑down test and a vacuum test.

After more than an hour of careful diagnostics, the culprit revealed itself: a small leak between the valves on the passenger‑side cast‑iron cylinder head. The original head builder had set the heads up for a 2‑inch exhaust valve. While they fit and sealed cold, they expanded under temperature and began interfering with proper valve seating causing the blow‑by. A small issue now, but one that would have led to failure down the road.

A Better Solution: Edelbrock Aluminum Heads

Without hesitation, Ethan Moradzadeh and Austin Bittle, JBA’s Director of Service, ordered a set of Edelbrock aluminum cylinder heads. Not only would they eliminate the problem entirely... they would add more power.

A setback? Sure. But also an opportunity to make the Blue Car’s engine even better than before.