i have a 1977 merc 115 i6 thunderbolt ign. engine with the backdraft ( backdrag ) carburators i have been cruising posts and a lot of people suggest replacing the cross over tubes on the carbs economizer system and blocking the tube with a .177 bb as this will keep from ruining the engine as this midrange economizer system seems to do more harm than good under the right operating conditions. Also does the bb go on either side or one side specifically or possibly one on both ends ? Lastly can i just block off the tube connection with the vacumm line caps sold at auto parts stores after all blocked is blocked so why but new tubes and block them or is this not a good idea as i am missing something that may cause damage to my engine ?