Quote Originally Posted by kacy View Post
The limiting factor on the engine is the heads, they just dont flow and need lot of work to be performers. A stock set of older model heads, TPI heads and Vortecs all out flow theses heads stock. The engine in your 89 Caprice should be a roller cam engine, unless it is you daily driver you would be better off rebuilding it, getting a used lt1/4 cam and the heads mentioned above.
VERY LITTLE HP difference swapping from the TBI heads to TPI heads on these engines. Even Vortec heads do not see large gains until you go to a substantial cam upgrade, different intake manifold, 454 TBI unit, headers, and larger exhaust. The stock TBI heads can make 300 HP with the right setup.