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Need info on Mercruiser 140 carburetor and linkage

M

mergatroid

New member
I recently acquired a 1979 VIP 16 footer with a Mercruiser 140. This is my first inboard. Unfortunately the previous owner swapped carburetors and apparently did some surgery on the linkage. The carburetor now installed is leaky and doesn't get full throttle travel, and probably needs a rebuild. I want to just buy the correct carburetor and go from there. I called a well known carburetor rebuilding company to figure out exactly what carburetor I need to buy, but they are kind of stumped by my photos and they don't want to sell me the wrong thing.

The carburetor currently installed is a Rochester 2 jet with the small mounting pattern. It has a non standard throttle arm, and the boat linkage has been modified to accommodate it. I have no idea how extensive the linkage modifications have been.

The way it is connected currently, when I advance the throttle the main rod pulls. This action is transmitted through a bellcrank to an obviously bent rod that pushes on the carburetor linkage.

My questions are: Which direction is the linkage supposed to act on the carburetor? What kind of arm is supposed to be on the carburetor that belongs on my engine? What carburetor belongs on my engine? Please refer to the attached photos. I can take more photos if anybody needs to see more.

Thanks
Rob
 

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The arm that is there moves the accelerator pump. You need another one in that area that goes to the choke lever that opens the choke plate on cold start, whatever the electric choke spring determines is necessary. The lever also opens the choke plate on a cold start a smidge when the accelerator is fully depressed. I think!
 
To be clear, I'm not asking about linkage and rods on the carburetor itself. Those rods and levers are all bent, and it's not even the correct carburetor. What I want to know is what direction the linkage from the boat is supposed to move the throttle arm when it accelerates. Is it supposed to push or pull the throttle arm? The arm on the current carburetor opens the throttle when pushed, but it's not the right arm and not the right carburetor for the boat. And the boat linkage has been altered.

I guess the best way to ask is what is it supposed to look like when the correct equipment is installed correctly? Can anybody take a photo of a correctly equipped Mercruiser 140 from 1979?
 
Just look down the throat of the carb and move the accelerator linkage back and forth, when the throttle plates on the bottom are wide open (vertical) that is the acceleration position. The cable pushes to accelerate
 
fastjeff said:
And marine carbs flood inwardly, not into the bilge! Get that thing out of there.

Jeff
Click to expand...

No they don't..........

Fuel pumps when the diaphragm fails there is a outlet fitting that delivers the fuel to the carb throat.

What some marine carbs have is 180 degree bent bowl vents so the carb sucks the fumes into the motor so they are not released into the bildge.
 
bertg said:
Just look down the throat of the carb and move the accelerator linkage back and forth, when the throttle plates on the bottom are wide open (vertical) that is the acceleration position. The cable pushes to accelerate
Click to expand...


Right, but do all Rochester carbs turn the same way? Do some of them go clockwise and others counterclockwise? This thing looks like it came from a car, and my boat linkage is messed up. I'm wondering if somebody put extra parts in it to change directions.
 
kghost said:
Look here for a old picture of the correct parts, item 24 - 37

http://www.marineengine.com/parts/m...hru-6229717/fuel-pump-carburetor-and-link-rod


The pic below is what it looked like originally........
Also the carb you have appears to automotive........Marine carbs do NOT have vacuum ports............
Click to expand...

If the triangular piece in your photo is the carburetor throttle arm, then it appears that the correct carburetor turns counterclockwise to accelerate, judging from the return spring. The one I have turns clockwise to accelerate.

If this is the case, then my setup is backwards. Based on the rod in my photo that was bent down, I'm guessing I need a counterclockwise rotating throttle arm that is positioned above the throttle plate shaft. Then I would bend my rod up to attach it, so it can turn the arm counterclockwise by pushing.

This seems like it would be correct, and this theory is consistent with the linkage in the carburetor in this photo:
 

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You may be correct........

problem is you have a automotive carb not a marine and not the original marine used back then.


If you have a chance and it may not be easy, try to reach out with someone with the same vintage boat as yours and take a look at there set up.

That would be the best course of action........besides you may find someone with the exact carb lying around.......there were hundreds of thousands if not over a million of these made.

The picture I attached here shows the carb for that motor.

The air/fuel adjustment screws face the passenger side of the boat and the linkage faces the back of the boat.
They kept the cable straight and added the V piece as a pivot point and cable end mount. Then they had a "S" shaped link rod that had a threaded center section that would lengthen or shorten the links length.
 
Last edited:
..."What some marine carbs have is 180 degree bent bowl vents so the carb sucks the fumes into the motor so they are not released into the bilge."

That's what I was talking about!

Jeff
 
Any fumes escaping from the bowl vents with the engine running will be consumed by the carb....the inverted J tubes' purpose is as Jeff stated previously.
 
Thanks for the photo. This looks like the same carburetor as the one in the vendor photo that I posted, except with a different throttle arm. What's the part number on the carb in your photo?

I live very close to Truman Lake in Missouri, so there are lots of boat shops around here. Now that I have a bit more info I may be able to shop around and see if anybody has old linkage lying around.



kghost said:
You may be correct........

problem is you have a automotive carb not a marine and not the original marine used back then.


If you have a chance and it may not be easy, try to reach out with someone with the same vintage boat as yours and take a look at there set up.

That would be the best course of action........besides you may find someone with the exact carb lying around.......there were hundreds of thousands if not over a million of these made.

The picture I attached here shows the carb for that motor.

The air/fuel adjustment screws face the passenger side of the boat and the linkage faces the back of the boat.
They kept the cable straight and added the V piece as a pivot point and cable end mount. Then they had a "S" shaped link rod that had a threaded center section that would lengthen or shorten the links length.
Click to expand...
 
mergatroid said:
Thanks for the photo. This looks like the same carburetor as the one in the vendor photo that I posted, except with a different throttle arm. What's the part number on the carb in your photo?

I live very close to Truman Lake in Missouri, so there are lots of boat shops around here. Now that I have a bit more info I may be able to shop around and see if anybody has old linkage lying around.
Click to expand...

http://www.marineengine.com/parts/m...hru-6229717/fuel-pump-carburetor-and-link-rod

Item 10
 
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