[Cliff R]

Without a spacer running my Holley 850DP carb the Tomohawk didn't fair well at the track. It was WAY down across the entire run. Adding a 1" spacer with no other changes netted a solid 2mph improvement on top end, and it ran nearly 2 tenths quicker than with no spacer at all.

My Q-jet absolutely HATED that intake. With no spacer at all it induced a 'stumble/hesitation/bog on the starting line that would NOT tune out. Adding a 1" spacer helped, but it still didn't rival the Holley carb with a 1" spacer. I suspect that the huge secondary throttle plates sticking deep into the plenum areas cause some sort of turbulence or distribution issues compared to square flange Holley style carb. Not sure, but it's a "turd" with a Q-jet sitting directly on it, and picked up nicely with the Holley carb once a 1" spacer was added.

A dyno will NOT show you hesitation/stumble/bog, or other issues that effect going from idle to full power with good traction as we don't load the engine that low or allow it to rev quickly to get into the "good " power.

Something else very few folks test associated with these things are drop base air cleaners. You can loose a LOT more power than you ever hoped to gain going to all intakes and/or spacers if you move the air cleaner lid too close to the carburetor. I've found that you need at least 3" from the air cleaner base gasket surface to the lowest part of the air cleaner lid.......FWIW........