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Rebuilding Rochester 2bbl on 1989 OMC Cobra 4cyls

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bob-the-boater

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Hello!

I'm planing to undertake a rebuild of the carburetor on my 1989 OMC Cobra TKO4 2.3l, which is a Rochester 2 barrel. I found this super helpful video:

https://www.youtube.com/watch?v=K3rGkqxlKq0

At 13:45 in that video, he talks about the two check balls, and mentions that for the smaller one, some of these carbs have one, some don't, and don't go by whether you find one in there or not 'cause these old carbs have probably already been rebuilt and you can't be sure it was done right. Instead, find out which is the case for your particular carb.

Excellent information - except, does anyone know where would you find out the check ball requirements for your particular carb? I do have the carb ref # off the unit - but where to go with that?

Thanks.
 
Jeeziz, please don't do what that guy does!! Having seen the videos, I wouldn't let him within ten feet of my boat. Use proper tools when working on your carb to avoid damage. There are screwdrivers made for installing jets. Regular flat screwdrivers can easily cam out of the jet and ruin the slot.
 
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o2batsea said:
Jeeziz, please don't do what that guy does!! Having seen the videos, I wouldn't let him within ten feet of my boat. Use proper tools when working on your carb to avoid damage. There are screwdrivers made for installing jets. Regular flat screwdrivers can easily cam out of the jet and ruin the slot.
Click to expand...

Well now I'm really intrigued. Anything else glaring?
 
Well removing the carb was disturbingly easy.

The four bolts that hold it onto the intake manifold were barely more than finger tight. With a stubby wrench on them, they turned free with little more than a light finger turn. I don't know what the torque speck is on these, but it can't be that loose. Looking at the carb, it looks like it's already been rebuilt at least once. But, for example, getting into it, the air horn / float bowl cover screws were barely tight as well. I didn't have to really grip the screw driver to crack them, juts a gentle twist with fingers on the screw driver.

Whic might explain why it's been operating as if there's a small air leak in the carb, and why it always smelled more like gas than it should.
 
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.....AND, upon disassembly, found the accelerator pump check-ball stuck in its hole. I'm guessing this would explain why it would hesitate (and sometimes die) when accelerating from idle.

And if that wasn't enough - on removing the venturi cluster, there are no emulsion tubes in the holes. I thought I read somehwere that not all Rochester G2s have them, and even those that were supposed to have them can run fine without them. Can anyone confirm?
 
Marine carbs are not like automotive carbs. They are more like what one would find on a stationary industrial engine. They also have some minor protections built in such that flooding conditions would dump into the venturi rather than all over the outside of the engine....so don't expect that you will find it is built the same way as ham-fist shows in his viddy.
So now you know. When troubleshooting look for horses, not unicorns. You probably would have solved all your carb issues by simply tightening four nuts and not buying a carb rebuilding kit and going thru all this drama.
 
o2batsea said:
Marine carbs are not like automotive carbs. They are more like what one would find on a stationary industrial engine. They also have some minor protections built in such that flooding conditions would dump into the venturi rather than all over the outside of the engine....so don't expect that you will find it is built the same way as ham-fist shows in his viddy.
So now you know. When troubleshooting look for horses, not unicorns. You probably would have solved all your carb issues by simply tightening four nuts and not buying a carb rebuilding kit and going thru all this drama.
Click to expand...

I appreciate the feedback.

Are you suggesting that the stuck check ball has so little effect that it's not worth fixing? (That really is a question, not a snarky reply.)

And, this sure looks like every other Rochester 2G I see on the web - did they do something special to these for marine applications that's not apparent?

And, just so we're clear - I think you're saying that the "missing" emulsion tubes is, in fact, not likely a problem?

Thanks.
 
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