2Jet Carb settings?

[Tycer]

My Mercruiser 140 (6920118) has the MCM 470 Rochester 2Jet that was probably the carb that came with the boat’s original 470.
When I rebuild it, what settings do I use? The carb numbers don’t show up on any chart I have found.

 

[Tycer]

[No message]

 

[Tycer]

Chris,
Is the main jet and power valve in the 470 carb appropriate for the 140? If not could you pull one of the carb #s from the chart for the 140 and post it here?

 

[achris]

My Mercruiser 140 (6920118) has the MCM 470 Rochester 2Jet that was probably the carb that came with the boat’s original 470.
When I rebuild it, what settings do I use?

Use the carb specs, not the engine.

The carb numbers don’t show up on any chart I have found.

Found it in the first manual I looked in... #03, All engines 1978-1984...

Chris,
Is the main jet and power valve in the 470 carb appropriate for the 140? If not could you pull one of the carb #s from the chart for the 140 and post it here?

Main jet on the 140 2GC are slightly leaner (0.062 as to the 470 of 0.066). The power jets are the same (0.052)

Chris....

 

[jimmbo]

I wonder what differences there are in the Air Bleeds, the spring tension for the Power circuit, off idle, and other circuits between the carb for a 140 and the carb for the 470

 

[Tycer]

Use the carb specs, not the engine.



Found it in the first manual I looked in... #03, All engines 1978-1984...





Main jet on the 140 2GC are slightly leaner (0.062 as to the 470 of 0.066). The power jets are the same (0.052)

Chris....

Thank you Chris!
I ordered a new kit from Mike’s with the smaller jet and the new power valve ( just in case)..

 

[Tycer]

I wonder what differences there are in the Air Bleeds, the spring tension for the Power circuit, off idle, and other circuits between the carb for a 140 and the carb for the 470

I wouldn’t begin to know where to look! The two GC was used on so many different applications, I wonder how many of those items were actually changed.

 

[achris]

I wouldn’t begin to know where to look! The 2GC was used on so many different applications, I wonder how many of those items were actually changed.

None. If they were different between applications, that would be called out in the spec sheets...

 

[Tycer]

I wonder what differences there are in the Air Bleeds, the spring tension for the Power circuit, off idle, and other circuits between the carb for a 140 and the carb for the 470

https://www.hotrod.com/articles/ctrp-1101-rochester-2g-carburetors/
Good race 2g article. Very little might actually apply to our boats but it really explains the circuits.

 

[jimmbo]

None. If they were different between applications, that would be called out in the spec sheets...

Since the Air Bleeds, Power Circuit Calibration are not considered Serviceable Items, their Specs would not be in Overhaul kits.

 

[achris]

Since the Air Bleeds, Power Circuit Calibration are not considered Serviceable Items, their Specs would not be in Overhaul kits.

I have trawled the internet, and nowhere does any site, marine or automotive, make any reference to different sizes in these items. I again suggest, they are all the same size for a 2GC carb. OP, don't worry about them!

Chris.....