panichat
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| posted on 27/11/10 at 03:20 PM |
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carb problem diagnosis help
Hi all
More carb tribulations - I've got a Weber 32 DFM on a 1.3 xflow, not had the carb working on this engine before as it is replacing a single
venturi ford carb. Carb has new jets of the suitable sizes recommended by the Dellorto suppliers and has had the service parts replaced.
The problem is I can't get the idle down to a reasonable level - it is racing badly even with the idle screw right out.
Any ideas? I'm wondering about vacuum leaks (although I can't see why that would make it idle too fast) or perhaps replacing the idle jets
with smaller ones.
Thanks
Dave
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marcjagman
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| posted on 27/11/10 at 03:25 PM |
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Could be mixture or/and timing.
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mookaloid
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| posted on 27/11/10 at 03:27 PM |
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is the butterfly closing properly? is there a bit of play in the throttle cable to allow it to close?
"That thing you're thinking - it wont be that."
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panichat
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| posted on 27/11/10 at 03:31 PM |
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I think the timing should be as the car was running fine with the old carb.
Play in the throttle is a possibility - I'll investigate.
Thanks
Dave
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russbost
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| posted on 27/11/10 at 04:44 PM |
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An air leak WILL cause it, but obviously check butterfly is definitely capable of shutting completely - if necessary disconnect linkage.
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rusty nuts
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| posted on 27/11/10 at 04:49 PM |
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As said already check the butterfly is closing properly, if not slacken the two securing screws and play with the butterfly to get it closed. Have you
got any slack in the throttle cable? you can check for an air leak using wd40 , just spray it around any suspect areas. Did you change the manifold ?
check for unplugged vacuum take offs
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panichat
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| posted on 27/11/10 at 05:06 PM |
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Yes, I changed the manifold - I'll take off and refit tomorrow to make sure it is seated well. Will also check the pipe from the pcv to the
manifold to see if it is leaking air.
The throttle cable has slack in, but when I disconnected the linkage it has a suspicious sticking feeling before it closes - I'm not confident
that it is right - another job for tomorrow.
Thanks for your help everyone.
Dave
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rusty nuts
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| posted on 27/11/10 at 05:13 PM |
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If the throttle linkage is sticking when in the closed position it's a sure sign that the butterfly is jamming on the bore of the carb.
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