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1971 Evinrude 50 HP idle adj?

H

heypal

New member
Hello,

So I have a 1971 Evinrude 50 Hp. The boat has been sitting inside and has not been run for about 20 years. So I rebuild the carbs and installed a new impeller (the reason why it was stored in the first place). Anyway, the motor does run and we took it to the lake last night with great success! However, how do you adjust the idle speed? According to the cover plate on the intake, it requires tweaking the trunion of throttle linkage? That seems a bit cumbersome. Also, when speaking with my local dealer he said that is to adjust the timing? He went on to say that there is a screw to adjust idle speed but I can not find one. Confused! See photo below on my FB page.


https://www.facebook.com/photo.php?...0199273036266.310462.687556265&type=3&theater
 
The threaded anchored "trunion" on the throttle cable is to set the idle rpm (NOT the timing)

The "set screw" mentioned is to lock the idle rpm in whenever you get it set to where you want it. This set screw is to keep the idle from dropping accidentally any lower than where you want it. It's somewhere near the bottom portion of the vertical throttle arm (the arm that connects the throttle cable at the bottom, and the timer base under the flywheel at the top).

To adjust the carburetors themselves, first make sure that the throttle linkage between the two carburetors is set so that there is no tension there. It must be adjusted so that the throttle butterflies open and close at the same time, that is you do not want tension to set up a condition where one butterfly would be closed and one ever so slightly open.

Next adjust the throttle roller so that the butterflies just start to open when the scribe mark on the metal cam is aligned dead center with the throttle roller... not before or after.

Hopefully you or nobody else has messed with the linkage between the vertical throttle arm and that nylon yoke that operates the metal cam... if you have, you will no doubt need to set the idle timing (worry about that later if need be).

To actually adjust the carburetor slow speed needle valves.............

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

Note 1: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

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http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
 
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