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1970 Vitesse 2L Mk2 Choke / Throttle synchronisation


PatK
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Hi All, my Vitesse is fitted with Strombergs 150 CDS, the front carb is 3224F and rear 3224R.

Only the front carb has a fuel enrichment supply, the rear one is fed the same enrichment supply via a tube.  On this carb fuel enrichment is supplied by a circular disc with calibrated holes, from small to large and this disc allows fuel to the intake side of both carbs, the fuel being drawn directly from the float chamber.

When the choke cable is pulled, the disc rotates and supplies more fuel the further the choke is pulled out. 

To match the increasing amount of fuel supplied, the carb throttle has also to be opened to get the right fuel air ratio, and this is achieved by a cam attached to the disc spindle, which opens the throttle more as more fuel is supplied.

The amount that the throttle is opened is governed by an adjustable bolt that contacts the fuel disc cam, and this is my problem as I can find no reference in any of my manuals on how to set up the clearance between the bolt and the cam ( the cam is attached to the choke cable as shown in the photo below as is the small bolt whose head is contacting the cam.)

I would very much appreciate any help that you wise people can give me.

Thanks

PatrickIMG_1572.thumb.jpg.0df2ae1774f11b88477bcaf4197f817f.jpgIMG_1572.thumb.jpg.0df2ae1774f11b88477bcaf4197f817f.jpg

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About where you've got it is a good starting point. It needs to have clearance with the choke fully off but to raise the idle speed before enriching. The corner of the cam (left of the cable fixing, directly below the adjuster bolt head, in your photos) is the reference point for that. Beyond that, it's a matter of judging the fast idle when cold. The book spec is probably a faster idle than your gut feeling says (though probably not as high as the Acclaim's >2000RPM figure).

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a gap  eg 1mm  but there must be a small gap    

you have non triumph carbs as you have the summer winter choke stop  quite useful its just push and turn to set more or less choke

having a start valve on the front and tube tp rear is quite normal

pete

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Pat,

According to my Autobook 723 manual the choke fast idle screw gap for the standard - earlier CD150 carb should be set at 1.6mm (1/16th). I can't find a specific setting for the 150 CDS carb. I always start with that setting. They are the correct originally fitted items for a MK2 Vitesse. 

Gav

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with wear and tear its not unusual to reprofile the lead of the cam so you do get a good fast idle  

as when worn it has a limited uplift in idle 

then they stall and soot up    needs a good fast idle 1500/2000 rpm so you actually burn the en riched  mixture 

the  first 1/2" of choke pull wants around 1000  but a lot more on full choke 

Pete

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8 hours ago, Pete Lewis said:

a gap  eg 1mm  but there must be a small gap    

you have non triumph carbs as you have the summer winter choke stop  quite useful its just push and turn to set more or less choke

having a start valve on the front and tube tp rear is quite normal

pete

Thanks Pete, I thought that these carbs were correct for this Vitesse!

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2 hours ago, Pete Lewis said:

with wear and tear its not unusual to reprofile the lead of the cam so you do get a good fast idle  

as when worn it has a limited uplift in idle 

then they stall and soot up    needs a good fast idle 1500/2000 rpm so you actually burn the en riched  mixture 

the  first 1/2" of choke pull wants around 1000  but a lot more on full choke 

Pete

Thanks Pete,that now makes sense as I thought that the idle was too fast, so I will set it at that setting.

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2 hours ago, Pete Lewis said:

the gap is there so it doesnt interfere with the idle settings  and makes it easier to pull the choke as this should use the lost motion levering so choke does not

react all back through the throttle 

Pete

Thanks Pete, good info.

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