40hp Johnson 1963 Carb Question

[twsnagel]

Hi everyone:
I’m trying to breathe new life into my dad’s old 40hp Johnson. It’s an RDS-25D but RD-25 brings up the right parts in MarineEngine.com.

I had some really generous people help me with the gearbox in the wanted section and that’s now complete and working.

I’ve pulled the carb apart since the engine won’t idle and will only start at higher throttles and 2-stroke mix leaks out the intake on the failed starts. I’m guessing something was clogged/blocked in the idle circuit.

Well, I opened it up and the packing had turned to crumbs in the rich/lean idle needle.

My local dealer can get the Sierra Kit 18-7010 – but does it fit my engine? The sierra catalogue only lists a 1963 Johnson 40 hp and doesn’t specify the engine model. Also, does it have the packing washers and the "other" washers for the idle needle? I called sierra and even their tech support line couldn’t tell me the actual parts in the kit. In particular, I need:

47 (x2), 0306027 Washer
36 (x2), 0307583 Washer, Packing
16 – 0302598 Gasket
64 – 0307778 Gasket

(Part numbers are from http://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1963&hp=40&model=RD-25&manufacturer=Johnson&section=Carburetor+Group )

Thanks for any help that you’re able to give me! I really appreciate it.

-Tyler

[crosbyman]

http://boatinfo.no/lib/johnson/manuals/ … on.html#/0

covers your engine

Joining AOMCI has priviledges 🙂

[Casey Lynn]

Why not get the real parts…..as in from a dealer?
They are still available in a kit.

[twsnagel]

Crosbyman:
Thank you so much for that link. I didn’t have it and it’s SO helpful!

-T

[twsnagel]

Pappy:
Wow, seems like an obvious question – but I coudn’t find a carb kit part number for the OMC kit from marineengine and buying the individual parts seemed very expensive. I assumed kits weren’t made anymore for a 52 year old engine.

I phoned up my mom and pop outboard store here, though, and lo and behold they had the entire kit hanging on the rack for $40 this morning. I had no idea that it was even still available.

So thank you so much!

-T

[twsnagel]

OK, I have another question. I got the kit, and the parts are in this photo:

The big problem is the packing for the idle needle. Here is a part diagram to refer to. It’s from this site:
http://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1963&hp=40&model=RD-25&manufacturer=Johnson&section=Carburetor+Group

So, here are the problems.

First, parts 36 and 47 were just an ungodly mess of decayed RUBBER and plastic, but there are no rubber washers that could match part 36 in the carb kit. Only cork ones. But they look the right size. Should they be cork or rubber? Part 47 (two of them) are plastic as I would have expected.

Second, at the above link, in the bill of parts, it says that two of the 36 washers are required. I can’t tell how many (rubber) washers I dug out because it was just a mess. The diagram just indicates the number 36 once, and isn’t clear how many there are from the picture. Should I stack two 36 washers up together? Is that how it works?

Third, how is the idle needle assembly properly assembled? There is the aluminum bushing, threaded in the inside (part 41) and then the packing washers (36 and 47) and then the 46 nut to tension the packing washers. Do I stack all this up on the needle and then put it in the carb body? Or put the washers in first and try to thread in the needle? Most importantly, how hard do I tighten 46? Just until there is enough tension for the idle needle to be adjusted without the bushing (41) turning in the hole?

Thank you so much. I have worked on a number of small engine carbs but have never encountered a needle packed like this.

You guys are awesome.

[chris-p]

Those cork looking washers are the packing washers. Lots of different looks for them, they all do the same thing though.

Put the bushing in first, if it fell out.

Then they say to put a plastic 47 in, then I put 2 or 3 of the packing washers in, 2 should be fine, then another plastic 47. The 47 washers keep the packing washers from getting destroyed, like you found. You can drop them in the carb in order, then put the packing nut in a turn, then start threading in the needle until it seats. You may need to tighten the packing nut a little, to keep the bushing from free spinning in the hole, while you seat the needle. Once seated, back it out 1.5 turns, then you can fine tune it on the water. Then tighten down the packing nut more.

Or thread the needle in, slide the gaskets in over the needle, then the packing nut over it all. There are many ways here to do it really, just personal preference.

You want the packing nut tight enough so that the needle doesn’t vibrate around loose, but not so tight that you cannot turn the needle at all.

[twsnagel]

Chris_P:
Thanks! Makes sense. I’ll reassemble and cross my fingers.

While I have it torn down this far, should I be inspecting the reeds etc. as well? I’m just looking for a running engine, not a complete teardown / rebuild. Does the intake manifold stuff often go bad?

[chris-p]

No, very rarely. But while the carb is off peek in the intake manifold and ensure all the reeds are there.

[twsnagel]

OK. Got the carb kit installed tonight but it’s not running correctly.

I can only get it to start with the choke OFF, which is really odd. And then, it runs really rough.

I’m trying to think what would be wrong – perhaps the float is stuck open in the carb? If it only starts unchoked, then it might seem to be getting too much fuel, if opening the choke and throttle is the only way to get it going.

Is there anything I should check before I pull the entire carb off AGAIN? I need to remove the starter, etc to get it off so I’d prefer not to if there are other things to check first.

As a side note, I have long since disconnected the remote control and am adjusting the throttle on the powerhead. It seems "spongy" and won’t swing past "start" if it’s not in gear. When it is in gear, I can advance the throttle to "fast" but then it springs back to "start". Is this correct behaviour? I know there are a bunch of spark advance / fuel saver things in this engine.

Thanks everyone for your help.

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