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Power drop off of idle.
https://slantsix.org/forum/viewtopic.php?t=64724		 Page 1 of 1
Author:  Demonator [ Wed Apr 08, 2020 11:48 pm ]
Post subject:  Power drop off of idle.
1st post, thanks in advance.
Fresh rebuild, everything is great except one issue. Takes off smoothly with tiny bit of pedal, give it a little more and it stumbles. Give it more gas and it takes off. Timing is 2.5 before .
Author:  Louise76 [ Thu Apr 09, 2020 10:34 am ]
Post subject:  Re: Power drop off of idle.
Idle fuel adjustment.
Author:  SlantSixDan [ Thu Apr 09, 2020 10:52 am ]
Post subject:  Re: Power drop off of idle.
Welcome here. This is probably not caused by an improper idle mixture adjustment, no. It's more likely a problem with your accelerator pump and/or your vacuum advance. Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download. Also follow Tune-up parts and technique suggestions in this post, and make sure you've done a proper valve adjustment.
Author:  Demonator [ Thu Apr 09, 2020 4:42 pm ]
Post subject:  Re: Power drop off of idle.
Thanks for the replys. Valves are set per spec hot, Carb has not been rebuilt so I will try that as well. Question about vacuum adv. I set timing with vac adv plugged at dist and carb, when I reconnect idle goes up and timing marks seem to retard a lot. Does this mean my vac adv is working properly. asap I am going to upload a video of of the issue.
As far as drivability, there seems to be 2 modes of drivability with this. One is a light pedal that has smooth power at low RPM and doesn't seem to get into the powerband, just nicely shifts up with just a little more than idle. This would be perfect for economy driving. The second is when you give it enough gas to get into the powerband and it accelerates rapidly. The stumble happens between the two so I am leaning towards carburetor. Maybe it s the transition from the idle circuit that is the issue. Time to study the links you posted Dan. Thx 8)
Author:  ProCycle [ Thu Apr 09, 2020 4:47 pm ]
Post subject:  Re: Power drop off of idle.
Quote:
Thanks for the replys. Valves are set per spec hot, Carb has not been rebuilt so I will try that as well. Question about vacuum adv. I set timing with vac adv plugged at dist and carb, when I reconnect idle goes up and timing marks seem to retard a lot. Does this mean my vac adv is working properly.
It sounds to me like the vacuum advance hose is getting plugged into the wrong port on the carburetor.
Author:  SlantSixDan [ Thu Apr 09, 2020 4:52 pm ]
Post subject:  Re: Power drop off of idle.
Quote:
Carb has not been rebuilt so I will try that as well.
Definitely.
Quote:
I set timing with vac adv plugged at dist and carb, when I reconnect idle goes up and timing marks seem to retard a lot
No, the marks are advancing a lot. This means your distributor is receiving vacuum at idle, which it probably should not be—what year and model is your car, is it a Federal or California emission car (as applicable), what transmission does it have, and which carburetor?
Author:  Louise76 [ Fri Apr 10, 2020 9:05 pm ]
Post subject:  Re: Power drop off of idle.
(Idle fuel adjustment.) My first & easiest step. Then I go deeper, as these other gents are directing. :)
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