67 3hp Johnson carb

[jloza]

It looks like I have a missing part on my carb (67 3hp Johnson). What goes over the 1/4 inch hole (I'm thinking it might be a screen?). If something is missing what does that do to the way it runs? See pic at: <br /><br /> http://tinyurl.com/x7u6 <br /><br />P.S. Thanks to Admiral & Captain for the info on the year and mixture.<br /><br />Jack

 

[Paul Moir]

Re: 67 3hp Johnson carb

Nothing missing there - it's supposed to be like that. I think for drainage when it's tilted up. That's just the air silencer by the way. It's held on by those two screws and one on the side through the exhaust plate.<br /><br />On earlier models there was a little clip attached to the (threaded?) hole above that one. It just supported the high speed adjustment a little.<br /><br />Good luck!

 

[jloza]

Re: 67 3hp Johnson carb

Thanks for the info. I hate it when they leave holes around. and some are even threaded, that do nothing.

 

[Paul Moir]

Re: 67 3hp Johnson carb

That engine hadn't changed much from the early 50s. In '68 they did the first major revamp. I think all those threaded holes might be parts of it's legacy.<br />Those 3hp's are really nice engines. Some folks around here suggest you run a 24:1 mix through them even though they're originally rated for 50:1. They have babbitt bearings throughout, and there seems to be a lot more of them from pre-64 (when they went to to 50:1) then post.<br /><br />Good luck!

 

[Toyman991]

Re: 67 3hp Johnson carb

I also have one of the little gems (1961 JW-17) and also wondered about these "orphan" holes. Turns out mine is missing its air silencer. What does this banana-shaped tube do? This motor runs like a little tasmanian devil without it. Is it necessary? What benefits does it offer?<br /><br />John

 

[Paul Moir]

Re: 67 3hp Johnson carb

There's a little screen between the carburator and the air intake silencer. Without it the engine runs a lot leaner. Of course, you can compensate completly for that with the high speed jet adjustment.<br />Other than that, it just makes it a fair bit quieter.<br />I don't think they put them on the later 4hp with the (airtight) fiberglass cowls.