1956 30hp Johnson Carb or WHAT!!!

[Zbosco]

Hey everyone ..
I have a 1956 30hp Johnson that I am trying to iron out a few problems ... seems to start and idle pretty good ... has an occasional miss though, but on the high end .. I am having great difficulty. Seems I can't adjust the high end jet to get the rpms .. and when I do seem to get the boat up on top of the water ... it surges ansd eventually dies ... I can restart fine ... and go through the whole thing again. You think it's the carb .. maybe the float .. or what?

Thanks ..

Zbosco

 

[tashasdaddy]

Re: 1956 30hp Johnson Carb or WHAT!!!

there are as simple as an lawnmover carb, could be packing around needle valve. i have a 58 35hp. what condition are the coils could be getting warm and failing. i did the complete electrical carb & impellar for $140. here is a good link to carb controls, http://www.iboats.com/bbboard/bbBoard.cgi?a=viewthread;fid=28;gtid=818798;gpid=818802

 

[Zbosco]

Re: 1956 30hp Johnson Carb or WHAT!!!

Thanks a bunch... the packing on the "low speed" needle is a little questionable .. which could account for the occasional miss ... but the "high speed" needle packing .. seems to be nice and tight. Could the "low speed" packing affect the high speed?

Thanks

 

[F_R]

Re: 1956 30hp Johnson Carb or WHAT!!!

Any 1956 Johnson needs to have two thing happen before you go dinking around with the float and stuff.
1. Check the compression
2. Check the coils. They are always cracked unless they have already been replaced. You can check that by removing the recoil starter and the inspection plate on top of the flywheel. If they are all dried-up looking and cracked, you need to replace them before wasting your time with anything else. Also take a look at the points through the same hole. Should be clean and gapped .020" Also check for good spark. By good, I mean jumps a 1/4" gap. Jumping the gap of the plugs held against the head doesn't count.

If all that checks out, my next question would be is your tank pressurizing OK? Then if that is OK, you can go into the carb and clean it.

 

[Zbosco]

Re: 1956 30hp Johnson Carb or WHAT!!!

Thank You for the reply ..
I have cleaned the carb already .. the coils are newer looking .. nice new blue coils. I have replaced the points ... and thought I had them gapped properly ... I will recheck. When the engine kicks ... and what I mean by kicks .. I mean when it gets up and goes .. it gets up and goes ... the engine will come up to speed ... and the boat will get up on top the water ... but that is short lived .. starts bogging down .. surges .. and soon will choke out if I don't come back on the throttle .. and she'll cruise slow ... but my question is .. can the low speed packing affect the high speed performance?

 

[F_R]

Re: 1956 30hp Johnson Carb or WHAT!!!

"but my question is .. can the low speed packing affect the high speed performance?" Packing no, except if the needle is spinning around out of adjustment, and even then only to a very small degree, certainly not what you are describing. You are evidently having a fuel delivery problem to the carburetor. That's why I mentioned tank pressure. Another sneaky possibility is the float needle and seat. There are different size seats in those things. If somebody has put one with too small a hole in it, it will run out of gas at high speed because you are sucking gas out of the carb faster than it can run in. Just a thought...

 

[Chinewalker]

Re: 1956 30hp Johnson Carb or WHAT!!!

Gas cap is tight? That is a pressurized system and if the cap isn't tight it will leak are. Also, check all hoses and connectors for air leaks...
- Scott

 

[tashasdaddy]

Re: 1956 30hp Johnson Carb or WHAT!!!

does it have the glass filter bowl, did you clean the filter, could be clogged with old varnished gas. also is it tight, with a good seal, as this could be the air leak.

 

[BoatBuoy]

Re: 1956 30hp Johnson Carb or WHAT!!!

does it have the glass filter bowl, did you clean the filter, could be clogged with old varnished gas. also is it tight, with a good seal, as this could be the air leak.

Carb bowl can't leak air since it's fuel under pressure. In fact, any leaks in the fuel supply at all will result in fuel spray. The air pressure side could be leaking air, but that would be evident when the tank cap is cracked - no hiss. Symptoms do resemble fuel supply problem which may be restriction, trash, water, etc.

 

[Zbosco]

Re: 1956 30hp Johnson Carb or WHAT!!!

Just want to thank everyone for their great input ... I rebuilt the carb and it purrs like a kitten ...

Thank You Thank You !!!!