Plugs in Mercury Prop

[bassinms]

I have a 150hp Mercury EFI that is running a 3 blade tempest prop on a Stratus 486SF. It seems that the prop is right for the boat, but it does not have the hole shot needed to pull skiers good. The boat seems to be a little sluggish when trying to pull a skier and someone mentioned to me that if I change the plugs out in the prop, it would make the hole shot better.

Looking at the prop, I found 3 black plugs (with holes in the middle) and I believe this is what he was talking about.

I have a couple of questions.

1. Would this really help the hole shot on the boat ??
2. How hard are they to switch out.

Thanks for your help.

 

[Varago]

Re: Plugs in Mercury Prop

"
I have a couple of questions.

1. Would this really help the hole shot on the boat ??
2. How hard are they to switch out.
"

#1 yes it can make a difference.

#2 yes they are very easy to change.

There are 4 different plugs, Solid, Small, Medium and Large, plus you can remove it for a huge hole. Around the top outside of the plug it says "Performance Vent System" with a S,M or L for hole size.

to start with if your rpm jumps up past 3-4000 rpm on take off you may need a smaller hole.

if your rpms only jump to 2-2500 rpm you may want a larger hole.

I am runing an Enertia that came with solid plugs, I installed a set of Small hole plugs and my rpm jumps to 2800 rpm then goes up from there. Others on the board my have a far better way to adjust for best hole shot, this worked for me.

good luck

Dave

 

[rndn]

Re: Plugs in Mercury Prop

The plugs are designed to allow some of the exhaust bubbles to flow along the cutting edges of the prop. This allows the prop to slip slightly during hole shots allowing the rpm's to get up into the power band quicker.

 

[bassinms]

Re: Plugs in Mercury Prop

Thanks for the great information. My rpms jump to about 3500 during take off, so I might have to try a smaller hole. I would assume my either has the large or medium plug in it now.

Can you tell me how to change them out ??

 

[jaxnjil]

Re: Plugs in Mercury Prop

i have them to and the mercurser dealer here told me the way he tunes them and likes the best is to;
get 2 solid sets. start with a 1/8 inch drill and drill each plug in the center.
test and use and work up a 1/16 in size till you start to lose perforamce and pop that set out, go back to drill size that worked and your good to go.
i asked another dealer if this was a good idea and he told me, yes thats the way they tune all there own boats.
takes less plugs and better results in the end
the plugs just pop in and out. if you have the prop on the drive you will probably have to pry on them to start them out
PS he also told me not to run them with out the plugs.