Denny, the engine has nothing to torque against. Automatic transmissions have some resistance even in park or neutral from the torque converter, same for manual transmissions, the clutches always drag just a little. I have run a number of engines this way a test stand. They always sound really good and rev like wild little small blocks since they have no drag on them.

Its well worth the effort to build a test stand if you do any amount of engine work. Its much easier to tune and test when its right out in the open, plus you can test the coolant system with a radiator mounted. I paint the engines after I run them, its easier to get apart if I have to.

I ran a flathead Ford on a stand just for kicks, it was so smooth running, you could set a water glass in the filter assembly with out falling off. Mostly because it weighed so much and idled so slow, but it was still kinda cool. This engine had the transmission and tail mounted drum parking brake. I put the trans in low and started applying the brake to load the engine down really good, it made for a better tune up since we could adjust the carb under a load.

Joe

1937 Chevrolet Inline-powered Streetrod