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When I take my foot off the throttle.........

PostPosted: Sat Feb 25, 2006 12:46 am
by mark030358
When I take my foot off the throttle when the engine is warm the idle speed does nor always return to approx 900 rpm. What happens is it will drop off rapidly the slowly come down from say 1400 rpm and eventuallt settle at about 900 rpm after say 15 to 20 seconds. I remember Keith mentioned this in one of his post but I can't find it. Any suggestions?

I am running dellortos on a sprint. And the car runs well otherwise.
Thanks
Mark

Re: When I take my foot off the throttle.........

PostPosted: Sat Feb 25, 2006 12:30 pm
by hatman
No help, I know, but mine does exactly the same and I had my Dell 'Ortos optimised on a rolling road session just a few miles ago.

Re: When I take my foot off the throttle.........

PostPosted: Sat Feb 25, 2006 2:07 pm
by marcfuller
What model of DHLA is installed in your Sprint?

Re: When I take my foot off the throttle.........

PostPosted: Sat Feb 25, 2006 3:02 pm
by mark030358
Marc,
Standrad 40's, non emission type.

cheers
Mark

Re: When I take my foot off the throttle.........

PostPosted: Sat Feb 25, 2006 10:42 pm
by freddy22112211
Probably not your problem, but a partly dud sparking plug caused this on my car.
Gordon

Re: When I take my foot off the throttle.........

PostPosted: Sun Feb 26, 2006 4:11 am
by twincamman
mine required a stronger return spring on the pedal--and lubricate the pivot points on the cluster up under the dash with penetrating grease -ed

Re: When I take my foot off the throttle.........

PostPosted: Sun Feb 26, 2006 9:40 am
by iain.hamlton
I have this on my weber big valve engine as well, but it is much better than it was after doing the following:
- Extra return spring
- Ensure the throttle cable is well lubricated and free
- Make sure there is not too much advance at idle and 1000 rpm (see threads on timing!)
- Stop all vacuum leaks - i had one on the headlight circuit
- Ensure the carbs are balanced at idle as well as higher speeds - if one carb is more closed than the other, it will prop the other open. Check balance by pulling each plug lead in turn. revs should drop the same amount
- Set idle speed with the engine warm or hot. Even when you have sorted everything else idle speed seems to temperature dependent.

have fun.

Iain