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Discussion Starter #1
Hi all - hope one of you carb gurus can help me with this
Twin 40 DHLA’s – spider S2, running lovely until I took the airbox off to do some work on it, when I put it back together it had a lumpy tickover and misses and sometimes spits on light throttle openings – if you run it stationary you can hear the engine and exhaust missing on one cylinder, on the road once its warm it accelerates lovely , no missing, but at any speed just maintaining steady speed is difficult because its not running smoothly – no backfiring

The only clue I have is the idle mixture screw makes absolutely no difference to the engine running on no.2 – you can screw it all the way in and all the way out – no difference.

I did have an air leak on no.3 O ring but sealing that hasn’t made any difference either

Spark plugs all swopped out – no difference

Timing spot on – electronic so no points

I checked the jets and blown them out – no difference



Is it possible some dirt got into the carb when I took the airbox off and blocked one of the passages, which passage would be blocked to make it run this way?

Thanks
 

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Not my flavor Alfa, but thought I'd give you a bump.

How goes it?
 

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The carbs have a supporting arm that "sprouts" from the engine mount and bolts to the back of the carburettors.

When you removed the airbox you would have to have removed that support arm. Changing the position of the arm when re-installing could have opened up a split in the o-ring on cylinder 2 (or others). Those intakes behave really badly with even the tiniest of holes (ask me how I know).

I wouldn't be at all surprised if you had a split intake. The intakes are cheap to buy, but a bit of a job to replace as the aluminium / aluminum / whatever intake manifold has to be removed from the head to allow replacement of the flexible couplings.

How did you repair the split on 3?

The carbs (particularly DHLA's) should be relatively trouble free. You were right to attack the sparky things first as that is where most woe's lie.

You may also want to report this thread on the carbs and injection forum to see what they come up with.

If you need to replace the flexible manifold thingies then please bear in mind that this is one of those jobs where the car demands a blood-sacrifice...
 

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Discussion Starter #5
Its the Alfaholics conversion so I've ordered new O rings and thackarys - but I'm pretty sure there's an issue with no2 HT - cracked cap or lead - just waiting for my week off to get all these jobs done...
 
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