HD8 idle air path

[mgcjag]

Hi All....looking at a friends 4.2.....diy rebuilt carbs......timming ok...i cant increase the idle with the air volume screws above about 550rpm...so its struggling.....ok if i give it throttle and it revs up fine....but all butterflies closed then low idle....im thinking a blockage but all 3?......anyone have a drawing of the exact idle path via the volume screw.....cheers..Steve

[abowie]

The slow idle path comes out as a tiny hole just behind the closed butterfly at the bottom.



I agree that it's unlikely that all 3 are blocked

Is it possible the timing is out, or the mixture is wrong?

[mgcjag]

Thanks for the reply Andrew...and Geoff who gave phone support.....so update..removed bells/pistons/volume screws..all looked OK....butterflies all fully closed as normal.....inlet to volume screws was larger than i thought...blew through the volume screw no blockages...jets were a bit too low so raised them 1/2mm reassembled and it fired straight up with good idle...and I can raise the idle with the volume screws...so no definite problem....but all now running good..Steve

[Gfhug]

That’s good news and you didn’t even need to hit it with a hammer!