Stromberg CD150 Throttle stop and missing fast idle screw

[Robin]

Sorry, another question...

My vitesse is fitted with CD150s which I think were fitted to 2000s? The 2000 manual indicates there should be a a throttle stop screw and a fast idle screw but there's only the throttle stop screw on mine. Are there variations of of the CD150 carbs i.e. some without a fast idle screw? If so do I just use the throttle stop screws when balancing both carbs?

 

[Pete Lewis]

on some only one carb will have a fast idle cam , as the throttle and choke are all linked up  so what happens on one happens on the other

yes there are many variations over the years

to balance you only need the idle screw the choke fast idle should have always a small gap between choke cam and its adjustable screw

the choke should have no connection with basic balancing   which relly just needs back the idle screw to just off/ wind it in 1.5 turns  then clamp the links so both throttles are in th same place  

you dont need any siily equipment to achieve the basics 

Pete

[Robin]

Hi Pete

I only seem to have the throttle stop screw on both carbs and the choke  on one (see attached) but no fast idle screw on either

 

[johny]

The first photo shows the fast idle screw and adjusts the idle revs when using the choke while the second pic is the stop screw. Each carb should have a stop screw which you use to ensure they are both working equally before doing up their connecting linkage. The fast idle screw is only present on the back carb as said linkage will automatically transfer its operation to the front carb. Note however once the choke is pushed in the cam must no longer touch the fast idle screw...

Have you got the free to download Vitesse/GT6 Triumph workshop manual from vitessesteve.co.uk ? 

[Iain T]

2 hours ago, Robin said:

If so do I just use the throttle stop screws when balancing both carbs?

I know it's obvious but don't forget to loosen the throttle shaft connection between the two carbs then adjust idle and balance. 

Also make sure there is some slack on the throttle cable or the back carb may be held back on the cable not the stop screw. I may be guilty of this misdemeanor....... 

Iain 

[Robin]

Thanks Johny and Iain

what was confusing is that in the Haynes 2000 manual it shows the position of the fast idle screw on the CD150 on the same cam as the throttle stop screw - which it isn’t!

[Robin]

1 hour ago, johny said:

The first photo shows the fast idle screw and adjusts the idle revs when using the choke while the second pic is the stop screw. Each carb should have a stop screw which you use to ensure they are both working equally before doing up their connecting linkage. The fast idle screw is only present on the back carb as said linkage will automatically transfer its operation to the front carb. Note however once the choke is pushed in the cam must no longer touch the fast idle screw...

Have you got the free to download Vitesse/GT6 Triumph workshop manual from vitessesteve.co.uk ? 

Yep I’ve got the manual but think this refers to CDS carbs not the CDs fitted to my Vitesse which looks slightly different

[johny]

The manual does cover the later carb but the majority of the info is for the CD as fitted to my 1967 Vitesse mk1. It answers every question you have asked with photos and diagrams...

Saying that of course carbs have been fiddled with over the years so you may have some other bits fitted...

[Iain T]

10 minutes ago, Robin said:

Yep I’ve got the manual but think this refers to CDS carbs not the CDs fitted to my Vitesse which looks slightly different

The big difference is the CDS has the choke enrichment disc mechanism as well as slight butterfly lift. 

[johny]

Definitely CD150s in the photos looking exactly the same as mine...