Interesting idle

[Bricol]

Got a crossflow engine with a twin choke downdraft weber, points ignition, manual choke.

 

Start it up - ticks over as tho you are blipping the throttle - revs up and down all the time. Will do this all day long, even when warm - pull up after a run and . . .

 

Also feels "fluffy" if you know what I mean -doesn't rev cleanly. But when asked to run, it does - pulls from low revs and just keeps going (it's used in a trials car). Not too good at maintaining speed in the higher gears when on the run and you get to a hill - but if you are trickling along in first, you can give ti full thottle and it'll pull nicely. But kanagroos a touch on light throttle when on the road.

 

So any suggestions - carb clean and seems leak free. Points seem fine - although timing open to doubt (I didn't set it).

 

Could it be an air leak on the inlet side? But wouldn't that make it simple rev high on tickover -not the blipping effect?

 

All suggestions gratefully relayed to the car owner.

 

Bri

[CageyH]

Accelerator pump diaphrahm?