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View Full Version : Causes of high idle? 1200 carb


matt_vaughan
07-10-10, 08:03 PM
Right, i need suggestions.

I've messed around with idel mixture, no difference unless it just bogs out and stalls...so dont think it's that (if anyone has a setting of turns in/out that's good please post cause i'm assuming now the idle mixture is wrong)

Also tried spraying all inlet with carb cleaner, no rev rise, so dont THINK there's a leak?

Could the distributor be causing problems?
comptoncj
07-10-10, 08:14 PM
If the ignition is advanced it will raise the idle speed, only slightly mind you, urm well could be a small air leak, make sure its not dragging air from the brake servo pipe, other than that, sounds silly but sticky throttle or choke? Is there an idle adjust screw on the carb as well as a mixture one?
matt_vaughan
07-10-10, 08:16 PM
Im not sure about an idle adjust screw, would have to check.

It could be the advance on the dizzy, as I changed the dizzy not long ago, and therefore could have fitted it wrong slightly.

It's only idling at 1k rpm, but its just a little niggle that's been annoying me for a while.
comptoncj
07-10-10, 08:23 PM
Could be a igniton timing issue, double check with a timing light, sure there are other people on here who may know more about the carb adjustments as ive only really used webers lol
ward
07-10-10, 08:34 PM
wat carb are you running?

because i can copy and post the picture and instructions for you
matt_vaughan
07-10-10, 08:36 PM
its a standard pierburg 1b on 1200.
Nova_Tek
07-10-10, 08:46 PM
Check the idle adjust screw. It's basically where the accelerator cable ties to the spring loaded linkage at the carb. There should be a screw there to push out and bring it in.

Best to get the idle mixture set up properly now as you've disturbed it.
ward
07-10-10, 08:49 PM
ill get it on here tomorow for you buddie
marc69
07-10-10, 09:54 PM
I had exactly the same problem with a nova, i eventually found that the gasket between the inlet and carb wasnt sealing, put new one in and realised that the bolt fitting was worn, there fore the car was leaking air and would not idle unless high. Put new bolt in manifold, tightened up and readjusted carb, perfect!
tom reid
07-10-10, 10:21 PM
I think your carb has an air bleed screw as well as the mixture screw, need to balance one against the other.