Choke adjustment

[jleyton]

Below is what someone has just posted on the Stag digest. I hope he won't me mind repeating it here but if it gets an answer to his problem, which is exactly the same as mine, I'm sure he won't mind

"I actually set my fast idle adjustment according to the ROM by using a 5/16 rod/drill between the cam and cam stop. Now what I've noticed is that the fast idle really only comes in when choke cable is fully pulled out and the cold RPM goes up by maybe 100 or so. According to the ROM, I'm expecting at least 400 RPM (cold 1,100-1,300). My problem is, since the RPM goes up by this nominal amount, my car, BW35, tends to stall. Should I adjust the fast idle screw with say using a 1/4 rod/drill or something even smaller in diameter? ( With the choke cable fully pulled out, isn't the fuel mixture being made
richer?.)
How can I increase the cold RPM without using/ creating a richer fuel mixture?

With my earlier cab setup, I adjusted the fast idle bolt to make my car fast idle when the the choke cable was extended out very slightly. you could say I used a 1/8th or 3/15 rod/drill. As I pulled the choke cable out more, the RPM would go higher.
The RPM would jump to about 1300-1500"

I'd just add that it seems odd to me that nearly all of the cable movement is just operating the enrichment devices and the fast idle only operates AFTER it's fully enriched. Surely, once it's started then you'd want a higher tickover but not an unduly rich mixture ?

Any advice gratefully received.

Cheers

Julian

[ampotter]

Hi Julian

I am also puzzled with the choke set up using a 5/16 rod/drill bit to set the fast idle. I followed this procedure after replacing the choke cable using a 5/16 drill bit and although the engine starts easily using the choke it does not idle at 1000/1200rpm, regardless of the choke position. I think the gap is to big using the 5/16 drill bit and as suggested a smaller sized drill bit/rod should be used. I believe that this adjustment does not affect the enrichment devices, only the idle speed when using the choke. When fully warmed up the engine idles at approx 750rpm.

Andrew

[V Mad]

We need to consider that this way of setting the fast idel may have been suitable with new engines and cars, but may not suit the situation 40 years on. There is no reason why you should not decrease the gap to get the idle speed you desire. However, the fact that you may have to do that is an indication that your engine, carbs and ignition system may not be in tip top condition.