spark plug for 1986 140hp evinrude

[dcolpitts]

I am currently running champion QL77JC4 plugs gapped at .040, have correct jetting, new t-stats water pump timing set at 18BTC. Runs great except for extented periods of idling (20-40- minutes)I have a 2mile 5mph no wake zone to get to open water. The plugs start to foul at about 30 minutes , I lift the cold start lever to burn off the excess fuel/oil mixture. Can I go to a hotter plug? I thought I read somewhere here that a QL82YC was used in this case. I don't want to burn up a engine but I would like to Idle. The Idle jet a 30 and is what the factory spec'd. Any advise would be appreciated.

 

[Dhadley]

Re: spark plug for 1986 140hp evinrude

What fuel?

 

[rickdb1boat]

Re: spark plug for 1986 140hp evinrude

As Dhadley suggests, look elsewhere for the problem. It should not be nessesary to change to a hotter plug if everything is set up correctly. Including a good carb cleaning and lync and sync.

 

[Walker]

Re: spark plug for 1986 140hp evinrude

I think your sparkplug gap is too wide. I run .030 to .032 on those older 4's

 

[P.V.]

Re: spark plug for 1986 140hp evinrude

Do the following, insurer that the engine is up to temp, not running too cold! Re-check sync and link just to be sure: DO IT !!! Check that any re-circ valves are not bad: causing puddling in the intake... and yes, the other spark plugs (the exact number escapes me, as OMC/Bomb has so many different ones now) will help for extended idling/low speed opeerations. I would caution you on just changing the plugs if you don't do the other things as the plugs will just be a "band-aid" and not solve specific problems :ie.. motor running too cold or recircs bad!!

 

[seahorse5]

Re: spark plug for 1986 140hp evinrude

Read my post int the topic " 86 rude 140 runs rich at idle ".<br /><br />When OMC and Champion redid the plug charts back in '95 or '96, they initially chose the QL82YC plug for motors like yours. They then changed all the plug numbers to QL78YC to make them the same for 40hp and up looper motors. The extended nose plugs will help idle. Gap at .030"