Some problems adjusting the slow speed needle

[Gas Giant]

'61 Evinrude Big Twin 40hp model no. 40353



Got the engine running, and it idles halfway decent, but I never did adjust the low speed needle properly, and I wanted to see if I could tune out a shake the engine had at idle.

So, I tried the Joe Reeves method today, which states as follows:

(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: 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.



But, I ran into some problems and am looking for some advice.

1) The very first sentence says to "Start engine and set the rpms to where it just stays running." I'm not entirely sure how to get my engine to idle any lower than it naturally wants to. The Idle Stop setting on the control box and the Idle Adjust knob on the engine itself only seem to be able to speed it up, not slow it down - it never hits a point where it just stays running, it always idles at a speed which seems fairly strong....so CAN it be adjusted another way?

2) I decided to proceed anyway....well, that stupid low speed needle valve wouldn't seat! I tried adjusting the packing nut tightness, but no matter what the needle just wouldn't seat - it would just spin and spin. In fact, it turned those packing washers into shredded wheat. So what happened? What do I do to prevent this from happening?

Obviously, I have to get more packing washers, but hopefully I'll be attempting this again tomorrow, so any pointers are appreciated.


Just in case anyone asks, the ignition is new, the engine has an even 100psi on each cylinder, and the carb has a fresh rebuild on it.

 

[Joe Reeves]

Re: Some problems adjusting the slow speed needle

The slow speed needle valve screws into a threaded aluminum barrel. Pull the needle valve out "with" the barrel to make sure that the needle valve absolutley does thread easily thru that threaded barrel and is not jamming in it.

Now, screw the barrel back on the needle valve about a half dozen turns or so and slip it into the retaining hole where it belongs, now add the 4 or 5 packing washers and the brass locking nut. Snug the locking nut down somewhat just enough so that you can turn the needle valve by hand but vibration will not affect it.

This should allow you to carefully seat the needle valve and adjust it properly.

Bad vibration at idle.... did you set the points properly?

(Point Setting Of Magneto Models)
(J. Reeves)

Set the points as follows. Have the flywheel key aligned with the fiber rubbing portion of the ignition points. Adjust the gap so that a .020 gauge will pass thru but a .022 will not. Should there be any question of the points being dirty (touching the contact with your finger would cause them to be dirty), clean them with a small brush and acetone or lacquer thinner.

NOTE 1: Should the operating cam have a small portion on it with the word "SET" imprinted, align this portion with the fiber rubbing portion instead of the flywheel key.

NOTE 2: Should the cam have the word TOP imbossed on the top of it, that is a cam that could be installed upside down and this is simply telling you which side is up. It is not a position where one would set the points.

 

[Gas Giant]

Re: Some problems adjusting the slow speed needle

Thanks Joe, I'll give it a shot today if any local places have packing washers.

 

[kfa4303]

Re: Some problems adjusting the slow speed needle

Hi gas giant. There is also an idle adjust screw at the base of the vertical throttle tower linkage. It's often made of plastic/nylon and may be corroded, but you should be able to screw thereby advancing the magneto plate and raising the rpms slightly. By turning the screw out, the prms should drop. Dialing in the idle involves finding a happy balance between the hi/lo speed needles and the idles set screw. It can be a little tedious, but once you have them set they should be fine for quite a while. Be sure to tighten down the bushings that the needles pass through once you have them set. this link may help.

http://www.duckworksmagazine.com/04/s/columns/max/24/index.cfm

http://forums.iboats.com/showthread.php?t=167352

http://www.outboard-boat-motor-repa...hnson 5.5 HP 1954-1964 Carburetor Tune-UP.htm

 

[Joe Reeves]

Re: Some problems adjusting the slow speed needle

Packing washers are part number 307583, 4 or 5 for slow speed needle valve only, available at any dealership. High speed is a brass jet.

 

[Gas Giant]

Re: Some problems adjusting the slow speed needle

Thanks for the replies. I got some packing washers today. I also spent a good amount of time extracting a broken bolt from the flywheel.

I messed with it a bit today, and got it to run better, but it still has a shimmy at idle.

However, while investigating why it won't shut off with the key, I discovered a wiring mistake. One of the black kill wires isn't going to the right spot. Unfortunately, the weather stopped me from checking it out any further, but its possible that the engine was only running on one cylinder because one of the kill wires was going right to ground.

I'll wire it correctly per the diagram and post back.

 

[Gas Giant]

Re: Some problems adjusting the slow speed needle

I think I'm good to go now guys, thanks. Weather permitting, I'll take this boat out for the first time tomorrow!