The 1950 Rocket 88 workshop manual talks about an “Index” on the choke housing but all I can find is the marks in the photo. They almost look like accidental damage marks.



Does the choke plate look in the right position?

Many thanks in advance

 

The AA was a fairly bizarre carburetor which didn't last long.

Suggest visiting the Antique Automobile Club of America website and forums and try to contact a poster there who goes by "carbking". Very knowledgeable on almost any vintage carburetor and knows of an appropriate substitute for the AA.

https://forums.aaca.org/

 

They look like deliberate marks to me, but that’s from someone with absolutely no knowledge of that carburetor.

 

Yes, those are "index" marks.
There is nothing wrong with a "turtle back" AA carb.
If you understand it.
Study your shop manual carefully when re-building or tuning it and you will be fine.

 

I’ve rebuilt the carb and the car runs lovely but it is hard to start so the choke is the suspect. I agree with you Charlie, I think the carb is a good design because of it’s simplicity and to be able to access all the workings without even having to remove the air filter is a big plus.

Thank you to every one who responded

 

I have a '57 and the choke housing looks similar. My comments are based on experience... I agree that you should follow your shop manual for basic set-up. I am not sure whether there is a heat riser valve on this car - my '57 was originally equipped with one and it is long gone. They were problematic in that they would rust and get stuck in one position, not always the right position. If you think it's the choke, I would remove the air cleaner and look at what is happening with your throttle plate. From a cold start perspective, what is the position of the plate and is there spring tension (choke spring) that is holding it toward the closed position, not fully closed? On my '57 the choke is set by pressing the gas pedal to the floor of the car once - I think many cars of this era functioned that way.

I think an earlier post suggested that you have two sets of index marks - a single one on the choke body and a number of them (rich to lean) on the cover.

Is the manifold choke tube intact where it connects to the manifold (can't see this from your photo)? Is the choke spring wound the correct way to hold the throttle plate closed when cold and then relax when warm?

Lastly when I look at your photo, I think there should be 3 cover retaining screws - I see the openings, but no screws or washers. I've added a picture that shows my choke housing and you can see some of the choke cover screws and washers (index marks are also visible). Hope this is helpful, David

 

Hi David,
I don’t think there’s a heat riser. The air cleaner is off and the throttle plate has spring tension and, once I press the gas pedal, the plate is fully closed. When the cam is on the fast idle I have the clearance on the throttle plate at 0.147” as per the book. My only issue is I’m not 100 certain where the cam should be as there are three positions. I’m afraid the second photo trying to showing the cam position isn’t very good but the choke rod has been straightened to get the 0.147” dimension
I have an index mark on the body of the choke and one on the cover plate that you can rotate to lean or richer the mixture and the choke spring is wound the correct way and in contact to close the plate when cold.
Yes there are three retaining screws - I just hadn’t put all of them in when I tool the photo - my bad.
I have a spare carburetor coming from the states and that may give some clues.
Thank you for your help.

 

At cold start, I think you should be on the highest step on the cam. You said when you press the gas pedal, the choke fully closes - this may be too much choke (too rich). With out changing any adjustments, I would try using a small screwdriver or wedge to open the throttle plate by roughly 1/8th to 1/4 inch and see if a cold start is improved and also results in a high idle. To do this, you may need a second set of hands, unless you have a remote starter. Good luck, David

 

Do you have this in your service manual instructions?


The index marks are to get you in the general position for a cold start. It sounds like you have the cover set correctly (the tang on the inside of the cover is hooked to the coil inside the housing) when you rotate the cover you should feel tension on the coil which applies pressure on the choke plate that holds it closed. It's a matter of experimenting turning the cover ccw or cw while starting it cold to see which best suits your environment, such as starting it up in < 0 temps or > 0 temps.

 

Thank you Supernice 88, I have that diagram in my manual and everything seems correct. I can feel the tension on the tang as you say and will experiment with position. I’m going to try what David said and wedge the choke open slightly. It’s not cold over here in the UK at the moment so hopefully will get a result. Working with a.slow turnover at the moment - due to too much cranking so battery on charge.

 

I forgot to mention. Another reason for the flexible adjustment is the coil looses its spring tension over time.