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Good Afternoon Group, I have a 76 Cutlass Supreme 350 Olds, Quadrojet Carb Automatic trans, been chasing Vacuum issue related to opening of 4 BBl,
I will show the Vacuum diagram, the issue is if I pull the Vacuum break Control it allows the 4 bbl to open, when vacuum is connected to the CTVS port the Vacuum break is Locked.
is it a problem with the vacuum break or the CTVS, any help would be greatly appreciated
Exactly what problem do you think you have? The vacuum break is designed to hold the secondary air valves closed at high vacuum conditions - idle and light throttle. If you are trying this at idle, this is exactly how the system is supposed to work. The secondary air valves only open when manifold vacuum drops to near zero, which is when you go to wide open throttle under load. The vacuum break prevents them from opening too quickly, which would cause a bog. If you are trying this in PARK by revving the engine, the secondary air valves should not be opening.
the secondary air valves don't seem to open when Vacuum line is hooked up as in Diag.
The secondaries don't seem to open when?
In Park / Neutral? (they should not)
When driving and going WOT? (they should, but gradually for a smooth transition)
Last edited by Fun71; December 18th, 2022 at 12:44 PM.
the secondary air valves don't seem to open when Vacuum line is hooked up as in Diag. please note EGE system has been eliminated.
We must get at least one question a month where someone is losing sleep over the fact that the secondary air valves don't open when they rev the engine in PARK. They aren't supposed to. The only open when there's load on the engine.
when Drivinng Full Throttle, when Disconnected the Vacuum line and drove it I heard that wonderful 4BBl open sound I hook up the Vacuum and I dont get it
correct I understand they only open when car is at proper temp and your full throttle in drive, I understand how it works the issue is at Full Throttle the 4BBL doesn't open so i replaced the CTVS when i had the engine out years ago and have been chasing this issue rebuilt carb and adjusted with vacuum gauge off manifold Vacuum PVC line on carb , just haven't heard or felt the Secondary's open so I tried something today and it worked so that's why i made the post. Just thought i could get some opinions on what might be the issue.
Excellent series started here. My uncle ran a shop for 50 years. This is exactly why he had lifetime customers. You were treated with respect. Patience and a smile, no one ever felt dumb for making mistakes as they learned.
December 18th, 2022, 12:12 PM
