Hi how do you set the idle on twin webers? i am running a 9a/kr head with twin 45's i have it running but if i take my foot off the throttle it cuts out, how do you adjust the idle so it ticks over smoothly? Thanks Ro
brand new weber 45s jetted from the factory for 2Lish cars will have it all rolling roaded but need it to idle for the MOT so i can drive it to be set up
The four screws with little springs under them that are closest to the manifold control the idle mixture (in conjunction with the idle jets). The idle speed is controlled via another spring loaded screw at the end/side of the carb, it'll be the one you see that rests against the lever arm. Screw it down (clockwise) until you get an idle speed of around 1000rpm, adjust the mixture screws one at a time by turning them inwards to weaken the mixture until the engine stutters or tries to falter, then turn them out until you get a smooth steady idle (do this with each screw one at a time). You no doubt need to keep adjusting the idle speed as you do this as you ballance the mixtures. You should end up with the screw around 1-2 full turns out from fully in. Try that as a base setting before you run the engine. If when turning the screws in the engine revs keep going up without faltering the the basic idle jets are too rich and will need changing. If you have to turn the screw out more than 2.5-3 full turns then they're too weak, as you'll find out when you go to drive it and it feels flat and fluffy on light throttle.
i have the car idleing ok now but it hunts around a bit. will it be safe to drive 5-6 miles to get it set up ok? as long as i take it easy.
Yeah no problem at all, you'll probably only be using light throttle so no harm at all even if it's too rich or lean.
