choke doesn't seem to work too well

[daverclasper]

Hi all

 

Twin Stromberg 150 CD carbs.

 

My car has always run on the rich side and would start in winter well (using the choke never increased the revs hardly)

 

I have rebuilt a second set of carbs and using a colortune the car is getting better MPG and running well.

 

I used all the choke assembly parts that were with the rebuilt carbs and it looks like the choke bars are raising the pistons and the cam is working the fast idle .

 

When starting the car in the morning, it is sometimes difficult to start. Uses lots of very short bursts of the starter as the pinion disengages straight away and it sounds like it is nearly starting.

 

When it does start the choke only seems to make a bit of difference, as it was like with the old carbs and also when the choke fully pulled out the revs drop off a bit as it did with old carbs. When hot it starts on the button

 

I seem to remember driving various Heralds years ago that the choke would increase the revs quite a bit.

 

The cars has had recent new plugs, points, condenser, Ht leads, coil, dizzy cap, rotor arm.

 

Any tips on getting better starting when cold much appreciated.

 

Cheers, Dave 

 

 

[Pete Lewis]

Dave fast idle on choke is only controlled by the cam on the choke spindle and the contact with the small

tappet screw that contacts it the gap may need reducing to increase the fast idle and on some the cam

gets worn so there is not much of a ramp , as you have doesnt matter how far you pull or twidle the gap

It does diddly squat

 

this can be filed to creat a better profile, , take a few mm off the leading edge makes more gap, and move the screw out further , then as you pull more choke the cam will open the throttle as the tappet bolt rides up the new cam profile,

 

pete

[daverclasper]

Cheers Pete

 

Did wonder about the cam or cams having wear but as the same/similar choke response on both sets of carbs wasn't sure.

 

That's a brill idea to file the leading edge, wouldn't have thought of that my self.

 

Thanks, Dave

[daverclasper]

Hi Pete

 

Was wondering how much to file off.  Maybe about 2mm at lead, gradually tapering off to about 10mm up the cam profile.

 

Cheers Dave 

[Pete Lewis]

you only need to file a bit   off  long enough to clear a  lead so there more room for the bolt to extend , leave the rest of the cam alone 

 

Pete

[daverclasper]

Cheers Pete

 

Started a treat this morning

 

thanks, Dave