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How does a triple weber choke behave?


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I just tried the choke on triple DCOE 40 151's with the default choke jets/tubes/air that came with the car. It seems to be too rich and no fast idle.

Can someone describe how 3weber chokes are supposed to behave when properly set up? What will the idle jump up to when engaged? What A/F should I aim for?


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Webers do not have a cold start choke. They have a cold start enrichment circuit and no fast idle. There's a little lever that gets pulled via a cable that increases fuel. What that AFR is depends on how you've tuned the car. It can be anywhere from 14 to 1 to 10 to 1.

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Thanks, I am 14 at idle with no choke. I did not measure A/F with choke but I see symptoms of too rich (instant bog) and no fast idle.

Is 12 A/F a good choke target at 60 degrees F or 11?

A good target would be as lean as you can go while keeping the engine running smoothly. That might be 12-13:1 on a cold start. If you're at 14:1 at cold idle without start enrichment, then I bet you're too rich when the car is fully warm.

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The Mikunis have an enrichment circuit but it is ONLY used to start the engine. Your not even supposed to touch the pedal while enrichments are engaged.

The Mikunis also increase air to raise the idle.

Once she's running I feather the throttle till she warms up

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I see AFR at very light cruise with choke system engaged as low as 11.5.

Quite frankly, I don't think you should bother with AFR. I never engage choke lever fully. I play with the lever until engine idle nicely, that's all. When engine is stone cold, idle is around 800-900rpm choke engaged , without it, engine stalls. after 1mi., rpm at idle are around 1200 so I play with choke lever to get back to 1000rpm. As soon as water Temp needle starts to move significantly, I close choke and engine idles at 800rpm.

I have no clue about my setup inside my carbs :)

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