1966 Johnson FD20 Excess gas fromexhaust

[heypawpaw]

I recently purchased a 1966 Johnson FD20C. I replaced the two fuel hoses to and from fuel pump, oil return line with clear tubing, fuel pump, new needle and seat, new float, and new packing washers on low speed adjustment needle (old packing washers deteriorated.) Took out for test run and after warming engine I fine tuned low sped adjustment turning needle in until engine started to cough at low idle then backed needle out until engine ran smooth. I noticed if I slowed idle speed is lowered slower than start/idle speed gas/oil leaking out out of exhaust. Also noticed at low idle oil return line has more flow than higher speeds. Is this normal for these old motors? Motor pushes 1448 flat with approx 500 pounds including me and gear 23 mph (checked with gps.)

 

[oldboat1]

sounds like you have it pretty well dialed in. Think you are saying at super slow idle you get some incomplete burning -- which would be normal, likewise the increase in oil return line flow, I think. I tune by ear, but technically you should have your idle set at about 650 rpms warmed up and in gear. Use the throttle idle speed screw on the side to adjust if it wants to run a little too slow -- plastic screw and spring at the pan on the throttle side.

(btw. Paw Paw the song or the ball player? You're probably too young to remember Charlie Maxwell hitting Sunday home runs at Briggs Stadium in Detroit ... usually against the Yankees, as I recall.)

 

[boobie]

Is the motor getting warm enough at idle ??

 

[heypawpaw]

Motor warms up quickly. No temp gauge but can hold finger on heads a couple seconds. Motor ran great today approx four miles round trip, only issue is gas slick at idle.

 

[lindy46]

Most of the oil you mix with the gas for lubrication doesn't get burned and exits through the exhaust. Perfectly normal. You notice it more at idle - it still happens at higher speeds but is less noticeable. You can get biodegradable TCW3 oil if you're concerned. Great that it's running good! Enjoy! BTW, if you haven't changed the water pump impeller, do it.

 

[heypawpaw]

Motor is running great but I have a couple questions: Are champion J8C plugs OK (or too hot)? Can I use Quicksilver gear oil? I have been using 87 octane non ethanol gas with marine sta-bil. Should I use 89 or 91 octane on this old motor? Is Sierra TCW3 OK or should I use OMC TCW3? Thanks, this site has a wealth of information from knowledgeable helpful people.
(oldboat1 neither but at 60 I'm probably old enough just not a baseball fan. Wife called me bae (short for babe) so children did the same and heybae was and is how they address me. Now with grandson its heypawpaw.)

 

[flyingscott]

I believe the J8C is the recommended plug for that motor so that is fine
Quicksilver gear oil is perfectly fine to use or any marine gear oil for that matter.
Any TCW-3 oil will be fine for that motor regardless of brand.
87 Octane will be fine for that motor. 87 Octane with ethanol may cause problems if the fuel system is original.

 

[HighTrim]

I find the J8Cs too hot, I prefer J6Cs in most of my 50s OMCS.

All of what you said is normal. However, check spark at idle. Timing light, or those neon spark testers that you can leave in while running. Ensure you are getting good spark at idle. Constant bright flashes, not dull or eratic.

A good quality oil will help as well. I personally like the BRP XD30 Oil in my motors. I find it smokes very little, and burns very clean. Also leaves little carbon build up inside the motor and exhaust, as it has cleaning agents. Sort of like running the Power Tune or Carbon guard in your mix.

 

[oldboat1]

Assume you are probably using a 50:1 mix rather than the earlier 24:1. Changeover was about '64, I think. You should be fine with 50:1 -- richer mix may give you a little fouling. I would try J4s gapped to .030 (can go to J6 if that seems better -- plugs are pretty cheap -- also might try the XD-30, as mentioned (think it has added detergent over some others). Maybe hold off on the StaBil for regular use, and just run with fresh gas and oil. Find an octane and brand that works best for you.

 

[racerone]

If the ignition is in good shape then it used to be J4J with thermostat and J6J without.---Good ignition is a magneto that will fire across a gap of 5/16" in open air.