Triumph Repair: zenith-stromberg 150 CD carb., zenith stromberg, haynes book

Question
QUESTION: Scott,

I'm having a ridiculously difficult time getting my carb set up. None of my manuals deals exclusively with the 150 CD model of Stromberg.

What it's doing now: The idle 'pulses' unevenly! I just noticed this afternoon that while I was trying to adjust the air/fuel mix with the tool whenever i pressed slightly dwon on the tool the pulsing stopped!?!? Is the diaphram in need of replacement?

Also, could you tell me how to set the carb up from scratch. I'm just not getting the interrelationship between the slow idle and the fast idle adjustment? Do I need to remove the carb to get it right?

Thanks a lot!

Jeff

ANSWER: The haynes Zenith Stromberg book gives you what you are looking for in an initial setup; The pulsing may be coming from a vacuum leak or a plugged port in the carb itself.

Don't worry about the fast idle; that is for when the choke is engaged under cold start conditions;  You can back all that off until you have the warm idle set correctly.

You shouldn't need to disassemble the carb to get it right.

First step is the initial needle setting,of the washer just below the bottom of the air piston valve.

I don't recall the # of turns out for the idle mixture; but it doesn't much matter.  The process is repeatedly setting the idle timing, idle speed, idle mixture until you get a maximum or optimal idle speed for the desired timing.

Let me know if this helps or if you don't have the haynes book.  If need be, sound back, and I'll pull it out of the book; the book isn't very good at describing, but its our only decent  reference for this carb.

---------- FOLLOW-UP ----------

QUESTION: scott,

what washer are you referring to? i saw no washer at the base of the piston. i can clearly see the needle coming out of the base of the piston but nothing that looks like a washer to me!?

here's what's going on: i can get it running by setting up the high-speed idle high enough to get it going. then once it's hot i back it off so as to be able to adjust the low-speed idle. then, when i try to adjust the high-speed lever to the tolerance the manual suggests, way before it's where it's supposed to be (.50mm, or .o20 inch) it starts moving the low-speed idle lever. what then happens is that it'll drive like a dream until i stop somewhere and then try to restart it! i have to always get out and reset the idle speed way up to get it started and then turn it back down to get it back to semi-normal but from then on it acts up! the car lurches, and pulses and at deceleration the idle dips way down and sometimes cuts out! none of this makes sense to me. i'm wondering whether the internal temperature control mechanism is out of whack?

i've not been able to find any vacuum leaks anywhere!

this is a real head-scratcher!

thanks, Jeff

here's what's going on!

Answer
Some of the needles have a washer as part of the needle assembly. most of the CD 150's I've seen have it, but then again there's alot of variations.

I'm not sure what the problem might be;  I would have to go through the carb myself to see what is set where; it could be the temp compensator or bypass assembly, but I've never thad them affect things as much as you describe.

Sorry I can't help more...