[Bob B.]

Originally Posted by factorystock

Best way to ruin a large V6 or a large diesel is run it at high rpms. These engines were designed to put out maximum torque at low rpms, unlike most V8's that are designed to put out maximum horsepower at high rpms. High rpms are great for a race car, but lousy for a working truck. V6 valves were mechanical that required periodic adjustment during scheduled maintenance. Why v6's weren't designed with hydraulic valves ( which Chevy v8's had during this period) continues to be a mystery to me.

Funny thing, the GMC V-6 had hydraulic lifters in some industrial applications. Very rare. I was told they actually used hydraulic lifters out of a later Chevy 235! The rocker arm shaft pedestals on the V-6 were made out of a special aluminum alloy that was supposed to help maintain constant valve lash whether the engine was hot or cold.

I never heard of valve train trouble on these engines, just that they gave poor fuel economy and were very expensive to manufacture. The V-6 was good for 200-250,000 miles in highway service when other truck engines were lucky to see 100,000.