What is the downfall of running one? Or isn't there any? Just curious.

No downfall really in running a small base cam...at least compared to NOT running one when rotating assembly requires it. :o

Under "normal" conditions, meaning a daily driver or a street/strip motor that doesn't spend time in the high (7500+) rpm range, there really isn't much risk when running a small base circle cam.

However, in high rpm, high lift, high spring pressure situations, (i.e., heads up motors) the reduced cam diameter can result in a broken camshaft when the camshaft literally "twists up". That is the primary reason that most of these types of sbc motors go to a 50mm or bigger cam.

And to add, you need to definately check the pushrod length b/c they should be AT LEAST as long than 1/2 the base circle reduction vs a stock cam's base circle.

I hope I have explained this OK???

pdq67