40hp Johnson 1963 Carb Question

[fleetwin]

Neither one of those pullers is up to the task, especially the three jaw puller. The flywheel and crankshaft tapers create quite a "lock" holding that flywheel in place, especially on that 40hp.
I’m trying to remember how you have checked the ignition, will it jump a 1/4" gap while cranking? Try the new plugs, then you might want to buy some of those inexpensive inline neon spark testers/monitors, available at most auto stores or Harbor Freight.
Digging into the ignition system without confirming a problem first may just create more confusion/problems.
Again, trying to remove that flywheel without a ring gear holder and the OMC puller might get you and the equipment hurt. Let’s confirm/rule out ignition problems before pulling that flywheel.
Maybe you can post a video of the engine running poorly, we might be able to help you zero in on the problem area.

[twsnagel]

Hi Fleetwin (any anyone else who might help!):
I have a strong spark. It’s bright blue. It easily jumps 1/4". I’ve put new plugs in.

I haven’t attempted to remove the flywheel since I’ve got the strong spark.

BUT… I think I may have found the problem. I believe the high speed orifice may be missing from the bottom of the carburetor bowl.

It is part number 69 on the diagram that I posted on the top of the thread on page 1. OMC part number 309935 replaced by 319534.

It is VERY hard to look down into the threaded passage, but the passage seems "too deep" to have such a jet in it. Before I hit the end of the threads, I can push 15mm of rod into the hole until it hits the end of the threads.

I can’t seat a "no flare" screwdriver of the right width in the bottom of the passage, it just turns round. It might catch a bit, but nothing positive.

Going against this theory is that I can measure the orifice size that goes into the centre of the carb bowl by *cautiously* putting the shank of small phillips-head screwdrivers into the bottom of the carb bowl. It is between 1 and 2 mm in diameter. This would match the "correct" orifice size of .067 in.

So, I guess there are two options. 1) The high speed jet is missing. 2) It is there, but the slot is messed up.

Would someone be able to measure the amount of thread there is in their carb before you hit the "end" of the threads? It should be possible to do this without taking the carb off the engine.

It missing would certainly explain why the carb is dumping WAY too much gas into the engine.

Thanks in advance,
Tyler

[fleetwin]

OK, so you did not have the high speed fixed jet out when servicing the carb. In any event, if there is a restriction in that passage that allows only .067" through it, then a high speed jet is in place. Just because there is a jet present, does not mean it is properly seated or the correct size (not messed with or drilled out). Perhaps someone has a spare carb for that engine you could try.
And sorry, I don’t have a 40hp carb to make that depth measurement for you.
Don’t mess with that flywheel unless you confirm there is an ignition problem, no sense creating more challenges unless it is absolutely necessary!
Any chance of posting a video of the engine running/misbehaving?
I know I have asked before, but did you replace the his speed nozzle gasket: #32
http://www.marineengine.com/parts/johns … Carburetor
The engine will run very rich at high speeds if this gasket is missing at high speeds.

[twsnagel]

Thanks again for the help!

It’s problem solved this morning – at least one problem solved.

The high speed jet has been drilled out and buggered up by persons unknown. The slot for the screwdriver is gone entirely and the passage is larger than it should be.

I took it to an outboard shop this morning and they confirmed it.

So – I don’t need anyone to measure anymore. But I do need a carb bowl. It’s been discontinued from OMC and so I’m now stuck finding a used one. I’ll try on ebay and perhaps post here in the free classifieds.

The only other option is to try to drill and tap the old jet to get it out, and I just had a $100-$200 quote from a machine shop to do that — with an uncertain outcome.

I’m sure this is a big part of why the engine was behaving oddly.

[fleetwin]

Good work buddy!
Post an add on the classifieds, I’m sure someone can help you for just a few bucks!

[twsnagel]

It’s alive! Through the generosity of a member, I was able to get a new carb. Bolted it on last night, and it fired right up. Thank you so much, fleetwin, and everyone else for the help.

Damn redneck fixes. Who would have run a drill bit through a jet? And broken off the screwdriver slots? Unbelievable. It’s amazing it ran at all.

Still have a big to-do list left:
– Find a new idle stop screw and spring (discontinued)
– Get the new cables and controls working
– Get a proper gasket in the gear case
– Some work on the hull
– Adjust the idle etc.

But she’s on her way now. Thanks again everyone!

-Tyler

[fleetwin]

Glad it has worked out, can’t kill an old 40hp!

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