Carter BBS Slant 170cui idle problems

[Schyrjajew]

Hello, we have a 71 Valiant. In Switzerland it was still built with the 170cui Carter BBS at that time. Number is 4930S
Since we have it, the problem is that it runs only in fast idle.
As soon as the choke is open, it no longer idles but stalls.
The colleague then recently overhauled and cleaned the carburetor and we wanted to mount and test it. But there was still the same problem.
Even the purple leather strap swelled up. So much for the quality of the overhaul kits... so we put an otherlether thing in...

The fuel pump is impeccable. There is also always gasoline in the filter. Not dirty.
When accelerating at a standstill, it also runs, just as soon as it should be idling, it turns off.
The idle screw we have already turned to the maximum and and and

Should I buy a new one? To what extent are these interchangeable? I can't find one with the designation 4930S. Can you also take one from the years 67-69?

 

[Charrlie_S]

Doesn't relate to your issue, but are you sure it is 170? In the USA the last year for the 170 was 1969

 

[Schyrjajew]

Doesn't relate to your issue, but are you sure it is 170? In the USA the last year for the 170 was 1969

As I wrote it is a 170 and this is 100% sure and it is also true that they built them here still in 71.

 

[Charrlie_S]

As I wrote it is a 170 and this is 100% sure and it is also true that they built them here still in 71.

Thanks for the reply. That is an interesting fact.

 

[Schyrjajew]

Thanks for the reply. That is an interesting fact.

no problem, you are welcome.
They built the Valiant as a Chrysler in Switzerland. looks exactly like the american ones but under the name of chrysler.
Because of the oil crisis they still put the 170cui as a basic one in.

 

[RustyRatRod]

It sounds like a vacuum leak to me. If you take a spray bottle of water and spray around the engine at the manifold and carburetor gaskets and all of the vacuum connections, if it is a vacuum leak, you will quickly find it.

 

[Brooks James]

It sounds like a vacuum leak to me. If you take a spray bottle of water and spray around the engine at the manifold and carburetor gaskets and all of the vacuum connections, if it is a vacuum leak, you will quickly find it.

Also partially choke off it with a rag

 

[RustyRatRod]

Also partially choke off it with a rag

The way it sounds, he might be able to close the choke and it stay running. If you can do that, you've just about confirmed a vacuum leak.

 

[Schyrjajew]

For what is this plug and what is under there? I have not seen that with the other BBS. Maybe this is related to the problem?

 

[Bugman]

For what is this plug and what is under there? I have not seen that with the other BBS. Maybe this is related to the problem?View attachment 1715707983

 

[Bugman]

Under that plug is a screw, I would make a definite mark on the side of the carb as a starting reference point. Count the number of turns and direction. You can go way too rich or way to Lean. If I remember correctly clockwise will rich in the mix. What is actually being adjusted is the spring tension. The air bleed size is not adjustable. Upon further investigation I think I got this backwards. The actual spring tension is not adjustable but I think the size of the air bleed is

 

[Bugman]

That ball is supposed to be seated at curb idle. No extra air

 

[Bugman]

That's the bottom view of that ball you can spray carb cleaner on there and see if it's leaking, sometimes a small punch and small Hammer couple of lite taps will reseat the ball

 

[Bugman]

 

[Bugman]

for Diagnostics and testing purposes wear that red arrows pointing right next to that red dot is The air supply hole for that air bleed. A small piece of cardboard covered up with duct tape will block off that air bleed. This Arrangement worked good when new 50 years going by it very well may be leaking at Curb idle,

 

[Bugman]

for Diagnostics and testing purposes wear that red arrows pointing right next to that red dot is The air supply hole for that air bleed. A small piece of cardboard covered up with duct tape will block off that air bleed. This Arrangement worked good when new 50 years going by it very well may be leaking at Curb idle,

 

[Bugman]

After removal of that cover plug, it is either aluminum or soft lead. small ,Hammer very small screwdriver punch through it, should pop right out. Turn screw clockwise to richen counterclockwise to lean

 

[Bugman]

That drill bit represents the idle air entry point for the adjustable off idle air

 

[Bugman]

Installs from the bottom up, the underside of this is what actually subject to idle vacuum

 

[Bugman]

It's hard to see but there's a spring in there pushing against a check ball, the vacuum or lack of vacuum will seat or unseat that ball, that part not adjustable

 

[Bugman]

It's hard to see but there's a spring in there pushing against a check ball, the vacuum or lack of vacuum will seat or unseat that ball, that part not adjustable

View attachment 1715708270

 

[Bugman]

The bottom of that screw visible from the top, it is tapered it is also plastic so be gentle. Turning clockwise will fully seat that taper in the air hole blocking off all air flow

 

[Bugman]

The bottom of that screw visible from the top, it is tapered it is also plastic so be gentle. Turning clockwise willfully seat that taper in the air hole blocking off all air flow

 

[Bugman]

Seated position no airflow

 

[Bugman]

Seated position no airflow

That spring is a tension spring so that screw will stay in one spot turn clockwise lightly seated no air flow into idle circuit. Turn counterclockwise unseats taper lets air in to idle circuit; this is adjustable , my first assumption was incorrect