just joined here, 115 top question

joec59

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Oct 18, 2014
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Hi to everyone, I'm new here. I'm repowering my 19' cruiser w/ a 1982 115 Merc TOP that I just bought. Seems to have been gently used and v. well cared for. One thing I notice though is on the carburetors(3) there seems to be an air jet removed from the middle and top carb but not the bottom one. I asked a friend who works on motors and he said "they used to do that(remove them) back in the day to save the motor". So I asked why only 2 and not the 3rd, he didn't know. Any ideas? Sorry, no pics, I'll get some tomorrow, but they're right on the face of the carb, any old heads out there remember any of these old performance tricks?
 

Mi duckdown

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Apr 14, 2007
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Serial number. Joe sorry after reading again New top end.??
 
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Chris1956

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Mar 25, 2004
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Are you referring to the brass jet on the left side of the carb, on the carb bowl cover? Is that what was removed? If so, those are the backdraft jets.

On that motor, air was pulled from the carb bowl into the venture, thru a small rubber hose, when the motor ran at mid range RPM. The jet that was removed was the carb bowl vent, and it would restrict the air flow into the bowl, causing a partial vacuum in the carb bowl. This leaned the fuel/air mixture somewhat.

Some folks think this design was a bad idea and defeated it, as is on your motor. Others ran it stock. It probably doesn't matter what you do with the remaining backdraft jet.
 

joec59

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Oct 18, 2014
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hey thanks for the reply, i had a cpl min today to look again and chris1956 i follow your thoughts, the remaining jet is size stamped @ .094. I wonder if that's what he meant by "saving" the mtr, maybe they ran too lean?, anyways if anything I'll remove the third if it's not frozen just to balance the mix across the 3 carbs. Mi the serial # is 6094133 which puts it as an '82. I've stripped down the evinrude of it's cables and harness and hope to swing the motors sunday morning. I've taken the best of 3 control boxes and made one like new and am waiting on a tilt/trim switch so i can finish the harness. once i get the merc on i'll run the harness, mount the control and also mount the tilt pump and plumb and wire it. I'm stoked! all the wiring, hoses and controls are in excellant condition and i'm chompin at the bit to get it in the water for a run! Time's running out though as it's starting to get a bit cool and we're having a couple days of rain so it may be another week or so. November on Great South Bay might be interesting!, most everyone is out of the water and wrapped now....we'll see how it goes, thx again
 

Chris1956

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Just so you know, Evinrude controls will not work with the Merc. Hopefully you have some Merc or universal controls. Also the bottom carb tends to run a bit richer than the mid carb, which runs a bit richer than the upper carb. That info will help you adjust the idle mixtures, if you ever need to.

A lot of guys/gals simply remove or disable the backdraft system, for good measure. I never had an ounce of trouble with the one I had. You probably want to plug the backdraft hoses on the carbs, as that extra air could cause lean running. Ironic isn't it.
 

joec59

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Oct 18, 2014
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Thx about the carb info, I think for now I'm going to leave it as is till I can get in the water and see how it runs, I am going to put some new plugs in though, but am baffled a bit about what I see in plug wires offered. Looks like I need to buy a kit and cut and build my own. Any feelings on champ vs. ngk? I'm kinda neutral but I guess it'll depend on what napa can get for me, btw, the control is merc and am waiting for the dash tilt switch and harness to come in the mail, I want everything to be merc original. have to install the cables and control harness, the tilt harness, mount and plumb the tilt pump, blah blah and on it goes! hahahah
 
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Chris1956

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Mar 25, 2004
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27,036
I never had any preference between Champ and NGK. I thought they were equally as lousy. Spark plug wires should be stainless steel stranded conductors. The spring ends and boots are pretty standard stuff.
 

joec59

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Oct 18, 2014
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really, stainless steel stranded?, seems pretty exotic, my budget allows for a build yer own set from belden. Their wire has always done a good job for me and the kit provides plenty of 90 and 45deg boots to copy the originals. Anything at this point will be a vast improvement over the stock original 32 yr old wires!! hahaha, continuity wise they're fine, porosity wise they're shot. So w/ new plugs and wires it'll really pop! Thx for your thoughts!
 
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