1970 Evinrude 40hp Big Twin - Slow speed needle valve

[New_Era]

Model 40052. Thanks to everyone's help here I replaced crumbling wiring harness with direct wiring set up, rebuilt fuel pump, rebuilt carburetor, replaced impeller and housing, new spark plugs, new oil in lower unit and took to the lake.

Started right up and ran great for quite a while. Go to start motor to leave and will not start. Finally saw that the low speed needle valve had vibrated clean out of the hole it goes into. There is a hexagon brass nut that the needle fits into but it doesn't tighten down. I think this is probably a packer issue, however, my main concern is that the threads on on needle valve don't seem to make contact with threads anywhere up in the carburetor opening. Do the threads on the need valve screw into the carburetor opening/hole itself or is there some type of receiver/nut that is supposed to be in there that could be missing. I noticed when I bought the boat that the needle valve could not be tighented very much. Could it be that there are old packers/washers in there that would keep the male threads on need valve contract the carburetor or is it common for the threads to strip?

Thanks,

Ron

 

[Joe Reeves]

Re: 1970 Evinrude 40hp Big Twin - Slow speed needle valve

Packing washer 307583. A few in the hole, tighten the locking nut as needed.

The needle valve screws into a threaded barrel. This barrel is a loose item that is held securely by the packing washers.

 

[tx1961whaler]

Re: 1970 Evinrude 40hp Big Twin - Slow speed needle valve

The needle valve should tighten all the way down into the carb. Don't tighten the needle valve to much, or you'll mess up the tip of the needle valve and/or the seat. There are two sets of threads in there; in smaller diameter fine ones way inside the carb body are for the needle valve. The larger threads (the one you see) are for the packing nut. Try threading just the needle valve into the carb without the packing nut. It should thread right in. The old packing needs to be cleaned out carefully, or the carb will get clogged.
The packing and packing nut are what keep the needle valve in place, purely by friction between the packing material and the needle valve.

 

[steelespike]

Re: 1970 Evinrude 40hp Big Twin - Slow speed needle valve

Threads are not likely stripped more than likely the old packing is hard preventing proper insertion of the needle.Remove the needle and nut and carefully pick out the packing with a stiff wire or tiny screwdriver.There may be a gland under the nut.

 

[New_Era]

Re: 1970 Evinrude 40hp Big Twin - Slow speed needle valve

Thanks everyone for your replies. I just checked and I don't think I have the piece way up in the slow speed needle hole that has the threads. Is it possible for this to have come out at some point? In looking at the BRP site for the motor I am not sure which part it would be (0303939 - Bushing, Needle valve) or some other part(s). Also, are there any other parts/pieces I would need to order. Also, is it something that can just go in the opening or would you have to remove the core plug etc.

I am so close on this motor.

Thanks again,

Ron

 

[F_R]

Re: 1970 Evinrude 40hp Big Twin - Slow speed needle valve

That is the part number for the threaded bushing. It just pulls out with the needle valve once the packing nut is removed, so yes somebody could have lost it. You will need the correct number of packings and any washers listed.

Warning: reinstall it correctly or you may wreck the needle valve tip. Slide the packing nut and packing parts onto the needle, followed by the threaded bushing screwed on just a few turns. The tapered end of the bushing goes toward the packings. Then push the whole assembly into the carb and snug the packing enough to keep the bushing from turning with the needle. Now screw the needle all the way in with your fingers till it stops when it reaches the seat. Now back it off 1-1/2 turns and tighten the packing nut enough to make it stay put. Fine tune it on a boat in the water.

 

[New_Era]

Re: 1970 Evinrude 40hp Big Twin - Slow speed needle valve

F_R

Thanks so much. I just went into the garage and thought I would look around the engine cowling just in case it fell out with the needle and GUESS WHAT!

There it was. Survived a 45 mile trip from the lake. I put it in and tomorrow after work I will fill up a garbage can with water and test it out. Thanks again F_R and everyone else.

Even with the parts manual and service manual I wasn't really sure what the part looked like until I saw it. Hope I can return favor some time.

Ron