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Solex (Zenith) 175 CD Air/fuel adjustment.

Rust Reaper

Banned
Joined
May 25, 2003
Car is running very rich now, with the idle trim screw all the way in (lean?)


I've looked at the haynes manual section for setting the air fuel (says "take your car to a registered emissions shop to adjust the CO") and have been able to put this together from the sources i've been able to come up with :

1) SU carbs typically have the "jet seat" adjustable through the BOTTOM of the carb float bowl, accessed either through a port, or by removing the entire float bowl itself. The solex 175 CD on my car has no such unscrew-able port, so i'd have to take the whole bowl off to adjust it, IF that is in fact what I have to do.

2) The jet needle itself, attached to the piston and diaphragm has an adjustment on it. It has a slot and a setscrew that can move it up and down 360', since there is only one slot on the threaded jet itself.


My question is, how do i lean this carb out? Without my own CO meter Its "seat of the pants" work, and the idle trim screw in and of itself isn't doing much/enough.


My knowledge has come from the 240 Haynes manual, and this thread i searched and found on here http://forums.turbobricks.com/showthread.php?t=91387&highlight=solex
 
Get some fuel injection, Carbs is a 140 thing. All 240's shoulda had fuel injection stock.

:roll:

Thanks for the help. I'd be glad to have fuel injection, and sooner or later (read when i build a motor) it will. But for now i need to insure this car, which means making it pass emisisons.
 
Ick, at least I didnt have to pass emissions when I had my 244 with B21A in it. Maybe go to the junkyard and find a B21A with a SU carb or get someone to send you one for cheap. They are far simpler and much less to go wrong.
 
you might have to big of a main jet, also somone may have messe around with the needles causing it to contach the inside of teh carb damaging it. that you you wil alway sbe rich because the needle will cause a small divit in the carb casting.
 
you might have to big of a main jet, also somone may have messe around with the needles causing it to contach the inside of teh carb damaging it. that you you wil alway sbe rich because the needle will cause a small divit in the carb casting.



Needle goes into a bolt-like fitting that has a hole in it. Needle isn't bent, diaphragm is ok and unbroken.



I guess i'll just tinker more.
 
ZS adjustment

There is a good Haynes manual that explains really well how the CD175 carbs work. You have to make sure all the mechanical adjustments are spot on. You want to make sure the warmup bypass devices on the side are working. They affect the fuel air mixture. The float level should be correct as well as setting the idle mixture screw.
 
there's a tool for adjusting the needle on 175CD, but i'm pretty sure the ones that are adjusted by needle don't have the lower adjustable jet.

my 175CDUS had the adjustible jet so the needle was set in one place and not adjusted.
 
there's a tool for adjusting the needle on 175CD, but i'm pretty sure the ones that are adjusted by needle don't have the lower adjustable jet.

my 175CDUS had the adjustible jet so the needle was set in one place and not adjusted.

On your adjustable jet version, was there an access port in the bottom of the float bowl, or did you have to remove the 6 screws holding it up?
 
Cd175

Pretty sure the ones on my 1969 164 were the type that adjusted through the top of the damper. You can buy a hex wrench tool they sell for Triumph TR6 to adjust them.
 
Pretty sure the ones on my 1969 164 were the type that adjusted through the top of the damper. You can buy a hex wrench tool they sell for Triumph TR6 to adjust them.


Perfect info. My carb has the indexing slots for the tool on the top of the piston chamber. I'll see if my local parts store has the tool, if not, i'm going to have to do something involving allen wrenches, a grinder, and some ingenuity.


the TR6 nugget was the real helper. Info came off a club site :)
 
Wow, it seems I just cant win....




Here's a picture of that adjustment screw. Despite all online knowledge saying that it's a 1/8" hex screw, here is what it looks like...
picture010lf6.jpg



So the tools online wont work.....
 
adjustment screw

Well, there's no telling what someone might have done or could have happened to a 40 year old carburator. The picture isn't too clear. It looks like someone broke the screw from what I can tell.
 
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