So here is the story. Changed from 16 x 31 to 16 x 36 mercury to herring. Both 5 blade Have blown carbureted 540s. Now I can't get idle low enough without stalling engines. Raise idle to 1400 or so rpm and it isn't bad, anything less than that and they stall. What best way to over come this?

without more information ,it is hard to figure out what is happening.what drives do you have and what gear ratio,also,how much hp,and what hull and length.

Maybe more base timing with adjustment for same overall timing to get stronger idle?

36 ft skater with 6's 900 hp someone said maybe recurve the distributor and others say the higher horsepower engines with big wheels us a mister of some kind that sprays a shot of fuel every time put put into gear will help. Sterling using that nd others?

Gear ratio. 1 to 36

lock the dist so no advance, try timing @28 will make a world of difference in idle, if you want to run more timing use a MSD digital box with start retard built in..

First step is if it idled ok before the prop change, and now its stalling, the extra load from the taller pitch is probably doing it. Couple things you can try. First, Id try backing the idle mixture screws out 1/2 turn each. Locking the timing out, will help, if it isnt already. I dont really know your engine setup, so not gonna recommend a certain degree, but my guess it will be somewhere between 30-34*.

I have seen where some guys will install a shift solenoid, that when you engage the transmission, a little solenoid will increase the throttle blade opening a tad. Not so sure though that you need this.

You dont reallly wanna be idling at 1400 and shifting in/out of gear. The trannies don't really care for that. This is why lightweight flywheels arent recommended in boats. The heavier flywheels help keep the engine momentum going when shifting around the dock.

That's exactly what is happening. i also took out a 1" inch spacer in the drive, Now there are no spacers. I though that might help a little, not hurt the in and out of gear stalling and maybe that did not sure.