cruising stumble
Thread Starter
Intermediate
Joined: Sep 2008
Posts: 40
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cruising stumble
My car idles and runs out fine but when cruising stumbles somewhat. Giving more gas takes it away till I slow down again. Just changed spark plugs which were carbon covered. When I turn the mixture screws all the way in, the idle does not change. Should the car stall or not? Not sure if the problem is carb or ignition. Can a Crane points replacement cause a problem? By the way, the car is a BB with Quadrajet. Any thoughts?
Thanks in advance,
Rob
Thanks in advance,
Rob
Melting Slicks
Joined: Jun 2011
Posts: 3,116
Likes: 598
My car idles and runs out fine but when cruising stumbles somewhat. Giving more gas takes it away till I slow down again. Just changed spark plugs which were carbon covered. When I turn the mixture screws all the way in, the idle does not change. Should the car stall or not? Not sure if the problem is carb or ignition. Can a Crane points replacement cause a problem? By the way, the car is a BB with Quadrajet. Any thoughts?
Thanks in advance,
Rob
Thanks in advance,
Rob
Also if the mechanical / vacuum advance of the distributor is not working smoothly the timing will be off.
1. check that the mechanical advance is working with in the proper range. Usually adds 22 degrees for base timing. base @ 14 ,36 @ 2500-3000. (vacuum advance disconnected)
2. check at idle the change of vacuum advance connected vs disconnected. should be able to advance ~ 10 degrees connected.
Because when you close the idle screw and nothing happens you may have a vacuum leak at the carb base , or any vacuum hose connected to full vacuum port on the carb. (PVC, Brake booster)
What kind of vacuum do you have at idle ?
