1956 Johnson 15 hp Carb Rebuild

[aMeyers11]

I'm doing the whole carb clean and kit on my old 15 horse. I just have a couple questions. My biggest confusion is how the throttle works? It appears that the roller that is linked to the carb gets pushed outward as the mag plate is advanced. But when my throttle is in the slow/stop position the roller isnt even touching the plate. And when the throttle is all the way advanced the roller is near the middle of the tapered mag plate. Is this right? It seems the throttle flap wouldn't even come close to opening all the way like this?.....my second question is regarding the high speed needle. I understand there is a packing nut for both high and low speed. But I dont get what this round peice with a gasket is for in the middle of the high speed needle? Thanks for all the help everyone. I will post pictures below.

 

[racerone]

At idle The roller is NOT supposed to touch the cam !!-----Motor has to be in forward for throttle to open all the way !!----That wee round piece is threaded and that allows you to adjust the needle in and out to controll the mixture..

 

[aMeyers11]

Alright the throttle makes perfect sense now, thank you! Just to clarify, The silver thing with the rubber end should be removed so the high speed needle can be cleaned. Will a new rubber peice come in the carb kit? Thanks!

 

[aMeyers11]

Hi everyone. I'm back. So I rebuilt the carb. I found that the float was rotten before and the needle had no clip peice to hold it to the float. I also noticed there was no round part to put the clip around the old needle? Anyways. I rebuilt it all seemed to be good. I went to start it. Primed it and it got hard. Turned it over many times. And it wouldnt start. I then noticed the bulb was a bit softer so I gave it a very light squeeze with my finger tips and then gas came oozing out of the top vent hole, again! I was a bit frustrated but it's a fixable issue at least. To be sure I checked the plugs and they were dry as a bone. Here comes the BAD part! So I went to put the bottom plug back in. And it wont thread in! I didnt over tighten it when I put it in or anything. They came out like normal. Top one went back in just fine but the bottom one wont thread like at all. I tried switching plugs from top to bottom. No difference. It just wont grab? So I'm not sure why the carb is doing that again. I'll take it apart and check the float and needle. I just dont get it. Also with the low speed needle that silver peice in the middle wouldnt come off so I left it as is. Is that normal? I set the needles to 1 and quarter out. But the top needle with silver peice I cant turn with the packing nut tightened. I'm sorry this was long and s lot of different problems in one. So basically my issue is I csnt get fuel to the cylinders because the carb is filling all the way to the top. My bigger problem is I cant get the bottom plug in! Really thought this project would be easier than it has become. Any help would be very appreciated. Thank you!!

 

[aMeyers11]

Good:

Bad:
Plugs:

 

[F_R]

Bottom plug hole is damaged. Even looks like it might have a Heli-Coil insert threaded in way too far (??). Whateveer, you will have either have it repaired, or replace the head.

The silver piece: The carburetor itself is not threaded. The silver piece is the threads and is held in by the packings/nut. It should and must be free-turning on the needle.

I can't get to the carb to see what's wrong there. But it's a simple carb and you just are not seeing something.

 

[oldboat1]

The original float needles didn't use the little wire clip. Replacement needles are machined at the top to receive the clip.

I wonder if the old helicoil is loose and spinning when you try to insert the plug. In any case, agree it's inserted way too far. I think you might have to start over or get a replacement head.

 

[aMeyers11]

I'm not sure if I could use the helicoil method if there is already one installed? I also cant seem to find any replacement head gaskets so I would have to do it with the head still on. I know you can use grease to help, but again I'm not sure it will work at all becuase I think you're right with some of a helicoil already being in there. And the cheapest and only head i could find was $80 with no gasket. I got this motor for free so I dont want to dump a ton into it. As far as the carb goes, the metal peice on the low speed needle is stuck in place and isnt rotating on needle. Maybe that's an issue? Unfortunetly I had to use the same needle seat screw because the one in the kit seemed to have too big of threads. so maybe the needle isnt closing. I'm not sure how that causes no fuel to get the cylinders but that's a fixable issue. Just a huge bummer about the head.

 

[aMeyers11]

My main question is if it would be possible to helicoil the bottom cylinder with it being previously tapped and with it looking like it already has an insert further in the hole? Thanks

 

[F_R]

IF, if those are Heli-Coil threads we are looking at, then sure you should be able to get that one out and properly install and stake a new one in.

 

[F_R]

Who told you that new head gaskets are not available? Part number 203247. An Evinrude dealer can order you one if he isn't too obstinate. Or, I'll bet a call to iboats will get you one from their OEM parts source.

 

[Crosbyman]

there is a lot of info for you in the Johnson bible on the boatinfo.no site

http://www.boatinfo.no/lib/johnson/m...64johnson.html

http://www.boatinfo.no/lib/johnson/m...nson.html#/136

you can also get head gaskets from vintageoutboard.com

https://www.vintageoutboard.com/coll...47-head-gasket


tim's outboard may also have a used cyl head for you I have purchased parts from them and his prices are not bad

just give them a call or email

http://www.timsoutboard.com/