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godamn twin su

sorted the flooding problem with a pair of superflow float needle valves and some proper floats...

just havin probs setting the mixture on idle

everything totally reset from scratch...mess with the mixture to get best idle...rev it once or twice,,goes lumpy,,,,mess with the mixture again,,get it ticking over sweetly,,,vroom vroom,,rev,,rev,,,lumpy again

on
and on ,,,and on

and so on,,,,,,,,,

am i missing something here, ??????,never had this with twins before...im ready for hitting the lot with a hammer,,,,,

Are both needles properly centred in the jets?

Lift the pistons about quarter inch and both should make same audible click when the pistons drop back down. They can be a right pain to get centred...

yer..the basic set up is all fine

brook shaw wrote:yer..the basic set up is all fine

id say not....

next time its lumpy spray a bit of wd40 around the gaskets and spindle, if they sharpen up you know you have air problems that can be hidden by the throttle disc position when balancing them.

if the wd40 doesnt affect anything and they then balance with a carb balancer so you will know that the air side of it is right (i.e no airleaks round the gaskets, worn/bent spindles etc etc, then it can only really be a dashpot/damper problem or a bent/worn needle or a bent/worn jet


they can drive you round the bend when they are first on a car, particually if they have been built from bits & bobs.

ive got a set that took hours to get the 'drop' on the dampers to match, then to match them to a pair of air chambers, then to match them to a pair of bodies, it really isnt a case of just throwing them together - its no wonder that they have a reputation for been a bit of a black art!

know what u mean rich-they are a bugger
they are a matched pair off an mg 1100 ,and ive put them on a cooper 998 inlet manifold with the 998 cooper linkages

about the only thing i didnt do is change the jets as my sharp eye usually sees an oval jet orifice but i suppose im gettin on a bit now,,and i have dodgy eyes...

im gonna get a couple of new jets,to go with the new needles i got off yourselves(along with the other stuff)

the throttle spindle wear is negligible,,ive actually never seen used carbs this unworn,,the core unit engine had about 14000 miles..
ive had more slop in "new carbs"

the jets must be a tad worn as the jets are near enough screwed up almost against the bridge to even get a reasonable idle

it has a 2 ring cam fitted,,i assume these arent as low a tickover speed as the std cam??

I agree with Rich, 99 times out of 100 a lumps / uneven idle on tickover with twins is caused by worn throttle spindles.

M

think ill strip and rebuild the old carbs off my 998 cooper and try these...
i know its barmy but the mg1100 carbs seem so unworn....but ive had the same prob before yrs ago on a very low milage car,,,,suppose stop start driving puts a hell of a lot of wear on the spindles