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Stromberg CD175 carbs (damper oil issue)


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It needs a new "O" ring. A simple, but fiddly job, best done in a plastic bag to avoid loosing the bits. take the top  off the carb, piston out, undo the needle retaining screw and take the needle out. Tap the rest of the assembly back up the barrel. The retaining clip, also known as a sprag washer will fly out, hence the need for the plastic bag. "O" rings are available from the usual suspects, Rimmers are a couple of quid.

Oring.PNG.db51128491e9a9c3d3c6eb9b6b40ec71.PNG

Doug

 

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thats assuming the 175 is top adjuster  ????  

what vintage is the carb   

 CD   CDS    bottom adjusters   

CDSE    CDSEV  etc  top adjuster ( as doug shows ) 

in as much CD CDS dont leak but oil can be consumed if it gets pulled over the top of the dashpot 

pete

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Hi Guys

Carb is a CD175, I already have the mixture control adjuster which has been adjusted via the dash pot accessed through the top level of the carb.

Would I be correct following removal of the needle, the loading Brass part is pushed out carefully through the upper section inclusive of retaining star,  mixture control and ‘O’ ring. Reinstated in reverse with the new O ring, assuming the previous adjustment of the mixture would remain as is.

Just to add when I replaced the diaphragm on both carbs - one carb retained the correct oil damper level - would you agree the O ring is my issue.

i look forward to your additional comments.

Best regards BRIAN 

 

 

 

 

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Brian,

Yes it's the "O" ring.  And yes, the needle comes out the bottom and the adjuster mechanism is pushed out the top, but you will loose the setting.

With the piston out the carb, use the adjusting tool to separate the needle and the adjuster. Also remember that the screw in the side is a locating screw not a clamp, it goes into a slot on the side of the needle and stops the needle from rotating, but allows it to move up and down. So when separating don't take the locating screw out or the needle will just turn around and around. Once separated take the screw out and carefully pull out the needle.  And when you put it back together ensure the slot and screw line up! 

 You'll need a small hammer and drift to push the adjuster mechanism out, I used the blunt end of an old drill bit. The Sprag washer can be re-used, it just holds everything in place. I found the new "O" ring once on the adjuster mechanism was a force fit back into the bore. Hammer and drill bit again.

Doug

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Hi Pete/Doug - O ring now installed successfully on both carbs although one was more challenging (belts & braces) your help was appreciated.

Slight issue with the mixture control as I believe the car is running rich (tested by slightly raising piston there wasn’t a significant change apart from the engine speed apart from staying increasing). Although normal even tick over at 800/900 RPM, significant improvement since O ring installation.

As the mixture control appears to be set at maximum travel adjustment (clockwise to weaken mixture) would it be possible to push/tap the star washer down a fraction further or is this not advisable - any additional thoughts?

Brian

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what is the position of the small washer on the head of the jet ??? 

 if there is lack of adjustment it may be the jet needs a move ??

are you diaphragms nice and flimsy gossamer or made from recyled elephant condoms 

there are some very thick ones about  they jam the piston from being a free mover.

but where is the washer   flush ( correct  )    sunken   proud of the piston  ( wrong)   ?????  

using the lift pins or lifting the piston is just lift a few mm and wait for a hint of change like a few seconds +50 rpm not a dramatic change 

and without lifting pins removing the air filter gives a very false reaction so it can be very misleading 

Pete

 

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The star washer/retainer is sat directly on the adjuster cam - when I was removing one carb needle up through the carb (last chance to remove) the seat of the adjusting cam was on the needle at max, unable to be split the thread apart  again. Although the other carb appeared adjustable as the needle was removed easily.

The diaphragms were replaced new although instead of sending 2 items they sent two joined as one twice noticed prior to install and they were gossamer thin.

The pistons were both free movers and closed with a metal thud.

Air filters were removed - spark plugs were all sooted up - prior they would have been brownish.

Should I consider replacement needle/cam/star washer or try and tap the cam/star washer down a little - just not sure which is my best route.

 

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I don't think the washer will go down any further if you've got it to the right position, it does need a good whack to get it down..

With the needle in it's very weakest position it will be sitting on the bridge and the base of the needle flush with the bottom of the piston. 

Take the rubber off and have a look where the needle is in the piston.

And I just had to check it :lol: it's confusing!  Clockwise enriches the mixture, you're screwing the thread into the body and lifting the needle. 

Doug

 

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Pete / Doug / Poppyman,

Latest update Following all your previous most helpful comments.

Prior to watching the video provided (both entertaining and informative) I had the car running although all the 6 plugs were sooted up - mixture to rich. I obtained a color tone kit and installed in no 2 & 6 cylinders although I was unable to achieve the blue flame when installing following warm up, color of flame remained bright yellow despite using mixture tool adjustment - just went overboard attempting to weaken the mixture.

Since watching the video I strip down the first carb to find I hadn’t seated the needle shoulder flush with the piston re-installed in correct seated position - now in a weaker mixture position. Unfortunately while attempting the work dismantling the other carb needle cam I had already damaged the adjusting screw for the needle making final mixture adjustment  impossible.

I believe with all the assistance I’ve received I’m now almost there my issue is obtaining a new needle inclusive of adjusting screw - star washer could be re-used. Rimmers appear to have a  needle only part no 519055 although I cannot find a replacement screw which controls the mixture adjustment - can anyone assist.

Many thanks for all your help on this issue.

Brian S

 

 

 

 

 

 

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Thank you Guys,

Burlen were very helpful and had the parts - needle part for reference was Identified under the delfrin washer shaft and being a Stag item.

Replacements due shortly as the mainstream parts suppliers were unable to identify.

Once again great help thank you.

Best regards Brian S

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2 hours ago, Brian Sculpher said:

Thank you Guys,

Burlen were very helpful and had the parts - needle part for reference was Identified under the delfrin washer shaft and being a Stag item.

Replacements due shortly as the mainstream parts suppliers were unable to identify.

Once again great help thank you.

Best regards Brian S

I got my bits from Paddocks (for a Stag) mainly because they are close to me and i can collect. Glad you are sorted Brian.

Tony.

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its a common search requirement to get the whole picture of what parts you are looking for is to 

dive into all makes of stanard equipment used across the whole model and maker ranges 

many parts are not listed by "A"  but will be Listed by "B"  so a full search ignoring your particular model and maker  will often find  what you were beginning to think was just elusive rocking horse pooh  

its good fun searching make it a good habit 

Pete

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Hi All,

Agreed it’s worth the challenge searching for parts especially with the assistance of TSSC people like yourselves :-

Pete / Poppyman and Doug especially not forgetting a good sense of humor added to the mix.

I will post a final comment with the car running when the parts are fitted with carbs color-tuned. Am now looking forward to doing the round Devon run on 5-Sept 2021.

Best regards BRIAN (in Plymouth) 

 

 

 

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