Carberator on 1972 40hp Johnson

[muchco]

Hi, I am trying to complete a carb job on a 40hp Johnson and I need some assistance. When the carb was removed I noticed that the packing nut (0305507) was loose and spinning freely. I also noticed that the packing (0307583) was in poor shape and one of the packing washers (0306027) was bent in half. Therefore I am inquiring as the the correct installation procedure for the needle valve, packing nut, packings ,packing washers and needle valve bushing, as well as the correct starting point to set the needle (turns in or out)? I have looked at the BRP parts page http://www.evinrude.com/en-US/Accessories/Literature/?popup=true and have a diagram but things still don't quite add up. Any help in this regard would be greatley appreciated. The motor model and serial number is: Model#EL72E Serial#J3626198.

 

[larky]

Re: Carberator on 1972 40hp Johnson

"I noticed that the packing nut (0305507) was loose and spinning freely."

does you statement mean that the threads are stripped, or it was just loose enough to turn easily?

 

[tashasdaddy]

Re: Carberator on 1972 40hp Johnson

i believe you can get a better view here, enlarge the diagram top left of diagram.http://shop2.evinrude.com/ext/index.aspx?s1=bf6ad09c53cead335fcfd8a6471c0f7f

i have had many with bad packing, and the nut spin, allowing the needle to suck air.

 

[muchco]

Re: Carberator on 1972 40hp Johnson

The packing nut was spinning freely, the threads are fine. Would the correct installation be to: Install the needle, nylon washers, packings and bushing as per the diagram on the BRP web site, then tighten down so as the bushing will not move but the needle can still be adjusted? If so I had tried this but the engine would not idle. If I loosened the nut and pulled the needle back beyond the adjustment that's there, the engine would speed up and idle. Is this idle screw an air or fuel adjustment. Is the engine starving for air or fuel if the needle is in too far? Thanks for the responses thus far.

 

[F_R]

Re: Carberator on 1972 40hp Johnson

You should have the needle backed out several turns before tightening the packing nut. Then turn it in until it seats lightly, then back it out about 1-1/4 turns for a beginning point. With the motor warmed up and running at an idle, fine tune the needle by screwing it in till the motor falters or sneezes, then back it out till it clears up and idles nicely.

The needle acts like a faucet, screwing it in restricts the fuel flow (lean fuel/air ratio) and screwing it out increases the fuel flow (richer fuel/air ratio). All gasoline engines require a narrow range of fuel/air ratio in order to run.

 

[muchco]

Re: Carberator on 1972 40hp Johnson

F.R. Thanks for the response. It appears that I had assembled the Idle jet correctly. I turned it in until it bottomed and then backed it out two turns. The engine would not start let alone idle. I then advanced the throttle and got it to start but when ever it was pulled back to idle it would stall. I tried removing the needle while at faster idle and the engine would speed up. If I left the needle partially out I could then pull it back to idle and it would run. I would imaging this would suggest some kind of blockage in the idle circut. How do you make an idle adjustment on this engine? Is it a carberator or timing adjustment.

 

[tashasdaddy]

Re: Carberator on 1972 40hp Johnson

my 71 50 hp, slow speed was recommended to start out at 5/8 turns for soft seat.

 

[muchco]

Re: Carberator on 1972 40hp Johnson

Bump