The Windham GTO

A mechanical-only rebuild reviving a correct Tri-Power triple-carburetor 389 — a factory option frequently lost to a simpler single four-barrel substitution over a car's working life.

Pontiac GTO 389 cubic inch Tri-Power engine

The project

Like many Tri-Power GTOs, this car had lost its original triple-carburetor setup decades ago in favor of a single four-barrel carburetor — simpler to tune and maintain, but not what the car was factory-delivered with. We sourced a correct-specification Tri-Power induction system and rebuilt the 389 to factory tolerances around it, along with a rebuild of the rear leaf-spring suspension using correct-arch replacement leaves to restore the car's original ride height and factory-intended handling balance.

Correct staged carburetor linkage — where the two outer carburetors only open under hard acceleration — was tuned and verified as part of the mechanical acceptance testing.