mercury prop for optimax

[blanked]

anybody have a tempest prop on there mercury optimax?

my rpm for my hole shot goes to 1500 rpm and hesitates there for a second or 2 and then jumps to 3500 rpm all during full throttle.  this is a new motor and was told to play with the plugs on the hub of the prop to eliminate this.  any feedback

[gamblerOH]

I had a tempest on mine for a while. Is yours a tempest plus or the older tempest. The plugs can make a huge difference especially on take off. I ran mine with 2 plugs out, that was the best setup I found for my boat. When you remove the plugs it allows the prop to cavitate which gets the rpm's going to help take off but this causes more prop slip so you will loose some speed. Like your dealer said, you;ll just have to keep testing until you get a good balance of top speed and take off. Remember plugs in = speed and plugs out= take off. With that hesitation it sounds like maybe you should take a plug or 2 out.

[blanked]

i have the tempest plus.  i guess i dont understand how the plugs can actually change the rpm of the motor .  i have 3 plugs in with the center opening of each plug about the size of a dime.   the dealer tells me there is a small, medium and large size plug but didnt know what size the dime size is  

[derick881]

As they say, follow the advice and remove the plugs one at a time until you get the right response.

The plugs won't change the top rpms of the prop.  They work by allowing exhaust gasses to leak out of the hub in front of the blades of the prop.  This will cause the blade to slip( less resistance in air than water) and this will allow the engine to rev up faster, get into its powerband faster, and thus allow a faster hole shot.

At higher speeds the exhaust is sucked out the back of the hub and the prop runs normally.

In the old days, you used to have to drill your own ventilation holes in order to improve prop performance in reguards to hole shot.  Merc has come up with the best system so far.