Distance between valve and spout

I am installing a Delta 1748 and the instructions say there is to be a minimum of 8" with a max of 18" between the valve and the spout nipple. I am replacing an existing setup and the holes are already in the ceamic tile for the spout and valve. Unfortunately the distance between the outlet on the valve and the middle of the spout is approximately 5" My question is what kind of problems may I encounter with not having enough the recommended distance between the two. The diverter on the spout is a pull down style diverter if that makes any difference Thank you for your time

The flow may backup and come out the shower regardless of the divertor position...

Works fine!!

Finished the job and with ony 5 inches between the valve and spout (6.5 inches if measured between the center of the valve and center of spout outlet) everything works great. No backfeed up to the showerhead. I imagine when giving measurements Delta will overstate the distance that is absolutely necessary to avoid any problems.

It relies heavily on back pressure to operate properly. Too little the pull down will not stay engaged, too much and water comes out of both the tub and the shower. There is some tolerence but not a lot.

distance

Too little only becomes a factor if the spout and trim ring interfere with each other, and Delta might have erred on the side of caution to be sure there was enough room between them.

Distance is a factor

Have to agree with HJ. The trim ring (escutcheon) is huge on this Delta faucet, about the size of a garbage can cover (actually it's 7.5") so distance between the trim ring and spout is a factor. With installation of spout and valve being as close as mine was it left 1.5" between trim ring and spout on the finished wall. Looks fine visually but much closer might be cause for concern.