Heading down a stromberg rabbit hole

[Acollin]

I believe I have a small problem with the stromberg starter bar. The small spring attached to the starter bar operating lever does not appear to do anything. However, when I manipulate the starter bar operating lever with a finger , I can raise and lower the idle without things bouncing back by activating any of the springs in that area.
For now, I would like a place to study up on how the starter bar works and how the spring end is supposed to operate. Advice would be good too, but I think this area needs a reset To work properly.

I am fairly certain I am in trouble here because I am fiddling around and really do not know enough to push through this issue. This came up as a problem when I was attempting to change my idle to time the car with a strobe.

My car was running great with good response to the throttle, just idling a bit too high (900 rpm) to get around the vacuum advance. I fear I should have left well enough alone.

Any advice here would help— even if the conclusion is too pack up the carbs and send them to a rebuilder.

be well all
Andrew

 

[hartmandm]

Hi Andrew,

Post a photo or two? I'm not sure what a Stromberg starter bar is. Do you mean the mechanical choke mechanism?

Mike

 

[Acollin]

Not a great pic sorry— I can do better and send more if you like. This picture at least shows the spring in question

 

[Acollin]

I have another related question after a bit of study. I have another set of cd150s for parts. I was looking at the assembled bits on the “starter bar” and it appears that the “ fast idle cam and lever” is a two piece assembly connected by springs that circle the “bar”. The two pieces meet on horizontal to vertical surfaces and are held together by springs which circle the bar. Much of this can viewed on pages 60 61 in the wsm. In the schematic #42 appears as one piece, yet has two lines coming from the reference number. I believe the two lines are saying they are actually two pieces held together by springs and actually operate as a single piece. Question: If my observations are correct, do these two bits of the “fast idle cam and lever assembly” ever have cause to separate and move independently? They seem to on the carb set up on the car, but not on the set up on my parts carbs. I‘m thinking I could have a weakened or broken spring on the inner most section.

Not sure if any of this is a help to those trying to help me, but it could help me unravel the magic and mystery of how all that stuff on the end of the bar is supposed to operate.

be well
Andrew

 

[hartmandm]

I see that WSM 145 indicates the starter bar is the bar the choke is attached to, closest to the air filters. The starter bar is only relevant when the choke is engaged. To adjust the "slow" idle speed, i.e. when the choke is off, you adjust the slow idle screws that make contact with the throttle bar.

Why do you think you have an issue with the starter bar behavior? Are you having problems starting the car or maintaining a high idle speed while the choke is engaged? From your first post it sounds like all you wanted to do was adjust the slow idle speed.

Mike

 

[rixter]

That contraption that your choke cable attaches to is serving multiple roles. It is "twisting" the starter bar shaft, which is lifting your piston and with it the needle. It is lifting the piston without increasing the opening in the airway because the starter bar is blocking the airway. The effect here is to increase the richness ratio. "Choking" implies strangling the airflow, but some carbs increase the fuel supply in comparsion to the air supply. Either way, the ratio becomes more rich for cold start. The cam plate on the end of the starter bar shaft is also lifting the butterfly plate on the engine side of the carb a bit.

As I am playing with a spare carb here in front of me, I do notice that there is a bit of movement on the cam plate before any movement of the starter bar shaft. I am not sure if this is play or wear on the spare I have here or if this is by design. In any case, these parts work together when the choke cable is actuated.

Rick

 

[Acollin]

This did all start with me trying to get the idle down to where the advance does not kick in, but like so many open doors,mit leads to another door— hence my wondering down the rabbit hole. Mike—Slow idle screws do not reduce the idle low enough. Other stuff must be askew.

I believe I understand the concept of the “ choke/ strangler” and what it does. The new door leads me : to how it does it— how do all those little bits do what they do? Ex1– the above pictured spring that does not appear to do anything with the choke activated or what I tried to describe earlier with fast idle cam and lever assembly— picture enclosed. That said, if I want to try to work on a system, I need to how what it does and how it does it.
So my questions from above still remain— how should that spring function and do the horizontal and vertical pieces of the fast idle cam and lever assembly ( pictured below) ever separate or function independently?

Trying to communicate all this through notes / writing is the greater challenge.
Thanks for your advice and your patience.
Be well all
Andrew

 

[hartmandm]

Is your tachometer accurate? It needs to be if you want to set idle speeds.

Mike

 

[Acollin]

My tach was set by the rpm reading on this old sears meter I have.

 

[hartmandm]

Quote: "Slow idle screws do not reduce the idle low enough." I think you should be able to stall the engine using the adjustment screws. Are you sure the starter bar is not engaged at all when the choke is off and the choke is not engaging the screw that turns the throttle bar?

 

[Acollin]

I would say that the choke cable is not taut when the cable is not pulled. But I can not say the “screw” that turns the throttle bar is not in play.
Which screw are you referring to ? A name or number from page 60 61 - stromberg carbs- in the wsm would help me.
Thanks

 

[hartmandm]

 

[husky drvr]

Andrew,

Have you ever tried to check the synchronization on your carbs?

Just curious,

 

[Acollin]

update : my car is running great— no hesitation- super throttle response, but dieseling when turning off the ignition key. Idle is around 1000 rpm.

I did the synching of the carbs by listening through a rubber hose and they sounded the same. So if the are off, it would not be by much.

I have never done an adjustment on the “fast idle adjustment” that Mike identifies in the picture. I will see if the “fast idle cam” is engaged when the choke knob is push into the dash. If it is, it would be slight. This, however, could be related to the picture posted in #7.

Do the two pieces of the “fast idle cam and lever assembly” work independently or do they stay held tightly together by a spring?

As I said in a prior posting, I can manipulate/separate them on my car with my finger and change idle speed— but on the parts carbs off the car, the two pieces of the assembly are held fast together by a spring— and I do not know which or either is correct.

Am I correct in thinking that if there is contact with the cam with the choke knob flush to the dash, if I freed the cam by adjusting the screw inward, I would then need to screw in the throttle stop screw to achieve a reasonable idle?


Thanks for all the follow up
Andrew

 

[RootesRooter]

"Dieseling" can be because of a worn needle valve. Look down the carb throats while running. You may see a 'river' of gas in one or both.
Worn throttle rod(s) will limit how low the idle goes.

 

[Acollin]

Update
Well just came in from the shop and found that I could not slip a piece of paper between the fast idle cam and the fast idle adjustment screw with the choke knob flush to the dash. As previously stated by me, in the time I have owned my car, I never looked at that area as a problem area. Amazed, I now have adjustment capability with the throttle stop screws and while I need to go through the carb set up regiment, I am currently idling about 800 rpm — car idling smoothly with good throttle response/ acceleration.
I still have some dieseling and I hope that too will disappear when I go through the carb set up.
Any advice here too would be appreciated!

Note: I did not expect this but on my two sets of strombergs the fast idle adjuster screw is a whitworth size 1/8w— the locking nut is American standard.

Back in the shop later today to try to sort the carbs and the deisaling issue.
Thanks all— props to Mike
Andrew

 

[Acollin]

I went through the dialing in process for the carbs as written in the wsm.

** I noticed that my carb pistons are not functioning the same. The front is a bit harder to raise and while they both come all the way down, the front comes down more slowly. Please advise— it must be a problem, but I do not know where to look for a resolution.
That said, after making adjustments to mixture and throttle speed, my car is running very well- maybe better than ever, but I believe that there is a carburetor issue that needs attention. If I had not raised the carb pistons with my finger, I would not know there is a problem other than dieseling at shut off.

please offer suggestions
thanks
Andrew

 

[hartmandm]

Maybe the metering needle is binding in the jet. Try re-centering the jet. The procedure should be in the WSM. If that doesn't fix the issue, then remove the metering needle and check if it is bent. You can spin the needle in a drill press or maybe a hand held drill to check if the needle is not straight.

Mike

 

[Acollin]

I read up on the metering needle centering and the did the procedure on my carb spares. I had a binding needle on the spare set. The process went well but as always, with my Sunbeam experiments, a question came to mind.

Question: If centering is all I want to do, do I really need to mess with the jet adjustment /mixture adjustment?
Could I simply loosen the jet bushing retaining nut- give it a “ sharp tap “ and center the jet and not lose what appears to be a good mixture adjustment?

Anyone do it this way?
Thanks
Andrew

 

[hartmandm]

You can try loosening the nut and tapping without tightening the adjustment screw. I'm not sure if that will impact proper centering or not.

You should be tracking what your adjustment settings are on each carb. I.e. how many turns out you are on each adjustment screw. Then you can easily get back to that setting when needed. If you don't know where you are at currently, you can slowly screw the adjustment screws in, counting the turns as you go, until the air piston just starts to move. Then it is the same number of turns in the reverse direction to get back to your current setting. Practice the procedure on your spare set of carbs until you are confident.

Mike