Intended only for 1976-2005 Mercury V6 2-stroke Outboards with switchbox (332-7778) ignition systems and sanctioned racers, please contact Mike Hill at STVracer@yahoo.com before installation with any questions.
 
Install:​
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1) Mount the +3 Boost Box securely in you cockpit where you can activate it safely. Run the cable with RED and BLACK leads to the powerhead through your rigging tube. ​
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3) Attach the RED wire to the White/Black bias circuit (it’s the upper left post with the rubber cap showing in this picture). The jumper wire that connects the two switchboxes should be retained. All other wires on this post should be removed. Next, attach the BLACK wire to a good Ground on the electrics plates.​
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4) Check and set your base timing to your discretion. Switch the +3 Boost Box to "Plus 3", your timing, it will advance 3 degrees. The reverse process also works. Set your base timing with the +3 Boost Box switched to "Plus 3". Switch the Box back and your timing will be retard 3 degrees.​
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Operate a safe timing range for your fuel octane, richness, compression.