1956 30 HP Johnson carb issue

[bzktm8]

The ongoing resurection of my 1956 30 HP has a new snag with the carburetor. I really need to post pictures of how bad this motor was when I brought it home. For now I am just trying to get the thing running correctly. I have been through all the ignition items with all new parts. Compression was 130psi top and 120 psi bottom cylinders. I rebuild the carb with a Sierra kit and cleaned out the worst nasty mess of gunk I had ever seen in a carb.
The problem I am having is during my 2nd lake test, the upper high speed needle cannot be adjusted or removed. I am puzzled how this happened since "lightly" seating then the initail setting to get started. The needle spins freely in both directions but will not seat or cannot be removed and does not go in or out. The packing nut is slightly snug - enough to allow turning the needle. I also tried loosening the packing nut completely to remove the needle, but it will not come out. I am lost - it is almost like the threads are stripped on the needle but it still should come out. Any ideas?

 

[Joe Reeves]

Re: 1956 30 HP Johnson carb issue

The top needle valve is the slow speed and should have a sharp long tapered point to it.

The bottom needle valve is the high speed and would have (usually) a shorter taper with a slightly blunt nose appearance to it.

Now, the top slow speed N/V actually screws into a separate threaded aluminum barrel that simply sits in the retaining hole and is locked in place by the packing washers so as NOT to move when the N/V is screwed in or out.

Best to start from scratch then to assume so....... remove all of the packing washers associated with the slow speed N/V, then yank/pull the slow speed N/V and the associated aluminum barrel out with it. Do whatever is necessary to make sure that the N/V will turn freely within that aluminum barrel.

When ready... insert the aluminum barrel back into the N/V retaining hole where it belongs, insert the packing washers, then the needle valve and the locking brass locking/friction nut, after which you can adjust the carburetor as follows:

(Carburetor Adjustments - Two Adjustable N/Vs)
(J. Reeves)

Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns.

Setting the high and low needle valves properly:

NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle valve adjustment.

(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, waiting for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top 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. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustments, 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.

-----------------------
NOTE: The brass locking nuts should be tight enough so that the N/V cannot turn do to vibration but just loose enough so that you can turn/adjust them.

 

[bzktm8]

Re: 1956 30 HP Johnson carb issue

Joe,

Thank you for the information. The previous owner spray painted the whole engine and I get the upper lower N/V mixed up since you can no longer read the labels. I was concerned about yanking on the needle to remove it after the brass nut barrel was loose, so I guess I need to pull harder. Your explanation of the aluminum barrel in the packing makes sense now why this N/V is spinning. I will be working on it again this weekend. Thanks again.

 

[lindy46]

Re: 1956 30 HP Johnson carb issue

I'd snug down the packing nut some more, and then see if the needle valve will adjust.

 

[bzktm8]

Re: 1956 30 HP Johnson carb issue

The local marina did not have the packing so I made 2 discs with cork and gasket material. The engine will only idle if I leave the choke on. The engine runs fine above shift speed. I attempted to adjust the low speed at lower rpms, but no improvement then it stalls. It always starts right up after using the choke the it revs and
shuts down. The only time it is on a tame idle is full choke...and plenty of smoke.

 

[nwcove]

Re: 1956 30 HP Johnson carb issue

sure sounds like its sucking air from somewhere its not supposed to.

 

[kfa4303]

Re: 1956 30 HP Johnson carb issue

This link may help. It's for a different model, but all of the steps are essentially the same for your motor.

5.5 HP Evinrude Johnson 1954-1954 Carburetor Tune-Up Procedure

This may help too.

Reviving a Vintage Big Twin - Part 1

 

[bzktm8]

Re: 1956 30 HP Johnson carb issue

It idles now, not perfect but the fuel gas mix is the next question. I used 4 oz gal, I have heard 16:1, 24:1, 32:1, 30:1, 50::1. I am using TCW3, but heard original oil was 8 oz gal sae 30 and I don't think that s a good idea. So which mix?

 

[Joe Reeves]

Re: 1956 30 HP Johnson carb issue

It idles now, not perfect but the fuel gas mix is the next question. I used 4 oz gal, I have heard 16:1, 24:1, 32:1, 30:1, 50::1. I am using TCW3, but heard original oil was 8 oz gal sae 30 and I don't think that s a good idea. So which mix?

You can use the 50/1 mixture with that engine..... 1 pint 50/1 TCW-III oil to 6 gal gasoline, a octane rating of 87 will be fine.

 

[powellc]

I also have a '56 Big Twin and your response to the original post here has helped me resolve the same problem with the low speed N/V just spinning in place due to the separate threaded aluminum barrel not being held solidly by the packing washers. My question is whether there would be any reason not to use just some Loctite to hold the barrel in place along with the washers? It doesn't seem to be necessary to remove it and I can't really understand what purpose it serves.

 

[GA_Boater]

I also have a '56 Big Twin and your response to the original post here has helped me resolve the same problem with the low speed N/V just spinning in place due to the separate threaded aluminum barrel not being held solidly by the packing washers. My question is whether there would be any reason not to use just some Loctite to hold the barrel in place along with the washers? It doesn't seem to be necessary to remove it and I can't really understand what purpose it serves.

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