I finally got a tach installed on my boat, and took it out for the first time with it yesterday. At WOT, I was getting 4800 rpms give or take 100.  Motor is a 1978 johnson 85 hp javelin. have a 14 x 19p SS prop. Will dropping to a 13 1/4 x 17 bring it up to the right level, or should I go with a 15p? Thanks!

I think that motor was rated at about 5,500 rpm. If that rpm was with a couple of people and your normal load, and dependiing on where you are, a 17 will probably about as low as you want to go. The reason for where you are comment, if your water temps are already in the mid to upper 80's and air temps in the 90's, that's going to reduce your rpm about 200 from what it will be when things cool back down this fall.

Now, if you were running a lot tighter than your regular load, with just your and your temps are still on the cool side, you might want to look at a 17". As usual though, I strongly recommend trying props before buying, they're not cheap and it's too easy to get the wrong one. It's possible your 19 could have a rolled blade that you can't notice with you eye and you go to a 17 and it over reves the crap out of it. I've seen blade edges the looked perfectly good but the motor won't make rpm, put another prop the same pitch one and the motor gain 400 - 500 rpm. So, try before you buy. Most dealer will let you try their used props if you just let them imprint a cc or hold a check for security. Might even want to check and see what some of your friends or neighbors have.

well, I must be the luckiest guy in the world. There was a garage sale with some fishing/boating stuff, and there it was. a 13 1/4 x 17 stainless steel prop, still in the box. $25