I know they help keep the cam from walking, and are really important with roller-cams. How important are they with a sizeable solid flat-tappet? (in a BB)

do not need one at all. The cam will keep itself in place

Cam buttons are only used with roller cams....you dont use them with a solid flat tappet.

The lobes on a flat tappet cam are ground at a slight angle. The lifters keep the cam pulled rearward.

Makes sense to me, thanks guys!

I've seen guys put them on solid cams just because! I never thought it needed but if I ever go back to a solid cam I may use one why not! Local builder here has brass ones made up he puts on all solid motors he assembles??

I'm running one on my flat tappet cam. But my setup is way different than most as I am running a set of composite mushroom lifters and some of the cam lobes had to be narrowed to make this work. If the cam ever decided to move forward I would have a bunch of broken parts so for the little money one cost I put one in.

PUT ONE IN! better to have and not need than to need and not have.

I ran this whole season, a little over 200 passes, with no cam button on my Comp roller cam. The motor's coming apart today. We'll see how much damage there was from this error in judgement.

Same starting line, same lane.

Finally got my timing cover off today. There are some very light marks on the inside of the timing cover from the cam bolts touching it occasionally. I think the biggest problem is the slop in the chain, way more that it should be from only 200 passes. I'm sure the front/back movement contributed to the wear. For the most part the cam is pulled to the rear by the distributor gear resistance. All that being said, it'll have a cam button from now on!

I don't like the torrington bearing style cam button. Have had them fail/come apart. Those little rollers play havoc with oil pumps. I use the nylon type..Comp Cam.

Nylo sounds like the best way to go. Thanks

A lot depends on the individual situation, from my experience. When I first went to a rollercam, I didn't know any better and ran without a button. No problems. I WAS LUCKY
The next motor needed one, and It didn't require a lot of effort to keep all the parts happy. I sold that good shortblock, (bad move) and built a mega block motor. That one has so much forward thrust, it pushed a reenforced cover out of shape so far it was .010 from crashing into the adjoining lobes! I put a milodon geardrive on it to give it a very stiff thrust setup, and it started to eat the surfaces so bad I now have it drilled and tapped for a direct oil feed through the cover to the button. That provides enough lube so it hasn't eaten the parts anymore than it had. No one can explain to me why this motor does this. It has bushed lifter bores, which should eliminate problems, I would think. So, I am all in favor of using a thrust button. For a test just pull the distributor, crank the motor for quite a few revolutions with the valve train in place and see what it does.
If it moves the cam forward at all, better figure out how to address that. You want zero movement, or very close to it. Especially if you run a stock type distributor, no crank trigger.

Glad I re-visited this post. All good info, they're pretty cheap.... Why NOT put one in?!