140 evinrude exhaust port modification

[dcolpitts]

the motor is a 1986 140 evinrude, when the boat sits in the water the exhaust port is about 1-1/2 inches above the water. The motor does not like to idle after 5-10 minutes, starts to load up. Have rebuilt cars checked and replace jets to factory specs, new vro pump,and elecs up to spec. Motor rus great other than this idling problem. I heard somewhere that you could drill or modify the exhaust port to help. Anyone have any knowledge on this. Thanks

[OBJ]

I remember the post okam but don't remember what it said. Try a search. Should be around here somewheres.

[walleyehed]

Keep your engine trimmed level, and gap your plugs to .040. for Idle. Drilling the holes clear through the exhaust chamber will decrease back-pressure, but that's not the way to adjust your Idle.EDIT: Exhaust PORT, is in the cylinder.......part of the block.

[seahorse5]

With the motor sitting that low, there is more backpressure and the motor runs rich.Make sure each cylinderhead temp is close to 140 degrees at idle, you may need new t'stats. Use the Champion QL82YC which is a shade hotter, less fouling, than the QL78YC that is recommended for normal use. Run a carbon cleaner such as Engine Tuner thru the motor a couple of times to help eliminate the built up carbon, but more importantly, clean out the fuel recirculation valves, hoses, and fittings. Use the correct service manual to adjust the carb needles. You might start by turning each one clockwise about 1/2 turn to see if she idles better.If you feel uncomfortable performing these checks, find a QUALIFIED tech that knows these V4 loopers.

[dcolpitts]

Update on motor status, The recirc valve and hoses have been cleaned and checked. The plugs which I think are recommend are champion QL77JC4 and are gapped at .040. The t'stats are the black ones, not the white. The boat has the water pressure gauge, but no head temp, I saw a post here about 2 sending units one on each head with a gauge and and a switch to go from port to starboard heads, I guess try that route can't hurt. Any other ideas would be appreciated, thanks for the replies