Choke valve position? Carb experts enter

[cgrooves]

Specifically talking about a Rochester 2GC, although the general question may apply to all carbs with an electric choke.

I recently rebuilt the carb and was looking down the throat of the carb last weekend to watch how quickly the choke was unloading. The choke adjustment is set at the middle index mark. I noticed that when the choke fully unloaded the choke valve wasn't completely vertical. Should I adjust the index marks from the middle setting to one of the leaner settings so that the valve is vertical when the choke is fully unloaded?

Basically, should the choke valve be fully vertical when unloaded?

 

[ziggy]

Re: Choke valve position? Carb experts enter

Basically, should the choke valve be fully vertical when unloaded?

yes..... after it's warmed up....
almost closed when cold after one full travel movement of the remote at the helm.

did you get the bimetel spring in the electric choke part on the correct side of the tang for the choke plate itself. easy to be on the wrong side of it when reassembling it. index at the middle as you have it... also the choke unloader cam can be installed incorrect too if your not careful when reassembling it....

 

[cgrooves]

Re: Choke valve position? Carb experts enter

did you get the bimetel spring in the electric choke part on the correct side of the tang for the choke plate itself. easy to be on the wrong side of it when reassembling it. index at the middle as you have it... also the choke unloader cam can be installed incorrect too if your not careful when reassembling it....

Thanks.
I believe I re-assembled it correctly, but I will look at the service manual to see if there is a good picture / diagram. I took some pictures of the carb from different angles before I removed it for the rebuild, so maybe I have a good shot I can compare it to.

 

[ziggy]

Re: Choke valve position? Carb experts enter

i believe theres a good pic of it in the oem service manual, if not, i can load up a pic for ya too if needed.....

oh, just so ya know. i ain't a carb expert.... but i did just rebuild my 2gc too. successfully.......

 

[Fishermark]

Re: Choke valve position? Carb experts enter

Yep. Bottom line - you want it completely open when it is warmed up. Adjust it accordingly.

 

[Fisnfool]

Re: Choke valve position? Carb experts enter

yes..... after it's warmed up....
almost closed when cold after one full travel movement of the remote at the helm.

did you get the bimetel spring in the electric choke part on the correct side of the tang for the choke plate itself. easy to be on the wrong side of it when reassembling it. index at the middle as you have it... also the choke unloader cam can be installed incorrect too if your not careful when reassembling it....

I have a Mercuriser 110 I/O. It is not an electric choke but which side of the choke plate tang does the bi metal coil go on?

It is a 1965 and the service manual picture / drawing is not clear.

The original owner remove the choke cover so I want to be insure it is installed correctly.

THANKS

 

[SuperNova]

Re: Choke valve position? Carb experts enter

The tang should go right in the small loop at the end of the Bi-metal spring so the spring can open and close the choke plate.

 

[Fishermark]

Re: Choke valve position? Carb experts enter

Actually, I believe there is a choke piston that will pull the choke open, the spring will only pull it closed. (When cold, the spring will overcome the pull of the choke piston, as it expands, the choke piston takes over and keeps the plate open). There is only a "tang" at the end of the spring - not a loop. Position it in such a way that the spring will pull the choke plate closed when it contracts.

 

[Fisnfool]

Re: Choke valve position? Carb experts enter

Actually, I believe there is a choke piston that will pull the choke open, the spring will only pull it closed. (When cold, the spring will overcome the pull of the choke piston, as it expands, the choke piston takes over and keeps the plate open). There is only a "tang" at the end of the spring - not a loop. Position it in such a way that the spring will pull the choke plate closed when it contracts.

Thanks for the quick reply. You are correct. there is only a tang.

To clear up a point: Does the coil become tighter when it contracts or when cold does it expand in diameter?

Right now I have the tang on the right side of the choke shaft, view from coil cover. This would push the choke open as the coil unwinds.

If the coil is to push it closed then I have it backwards.

The cover is marked, so clockwise would be leaner and counterclockwise would be richer.

 

[Fisnfool]

Re: Choke valve position? Carb experts enter

Thanks for the replies.

Since I learned that the choke bi metal coil should CLOSE the choke, I fixed the problem.

I have a 2 barrel GM carb. I took off the choke cover with the bi metal coil attached. I put the cover on a dish of ice with the coil up so I could watch it.

As the coil cools, it opens wider, it does not contract.

So, in order for this to push the choke open, it gets installed with the coil tab on the forward or right side of the choke lever as seen from the open choke housing.

Then as the coil cools, it rotates counter clockwise, closing the choke.

This matches the rich / lean adjustment direction indicated on the choke cover.

I found a carb repair site that stated at what temp to set the choke closed:

"Setting an automatic choke is quite simple, even if an after market choke is used. For integral chokes, loosen the retaining screws such that the choke will rotate freely. Adjust the choke such that the choke plate just touches closed at 68 degrees F. (65~70 degrees is close enough). Tighten the retaining screws. For the divorced choke, the same setting applies, but bend the operating rod to set the choke plate."

GONE FISHIN