2 Holley questions
Thread Starter
Pro
Joined: Nov 2001
Posts: 534
Likes: 6
From: Cave Creek AZ
2 Holley questions
1972 LT-1
1) What would cause the vacuum secondaries to stay closed even at high rpm. I have plenty (17-18) of vacuum at idle. The carb has just been thoroughly restored (6239). I can open them by hand but when I rev it by hand and watch the secondaries - they don't seem to be opening.
2) Secondary float is continuously binding up causing flooding. Any suggestions here beside pulling the needle & seat every week and re-adjusting...
Thanks
Dave
1) What would cause the vacuum secondaries to stay closed even at high rpm. I have plenty (17-18) of vacuum at idle. The carb has just been thoroughly restored (6239). I can open them by hand but when I rev it by hand and watch the secondaries - they don't seem to be opening.
2) Secondary float is continuously binding up causing flooding. Any suggestions here beside pulling the needle & seat every week and re-adjusting...
Thanks
Dave
Safety Car
Joined: Oct 2004
Posts: 3,921
Likes: 731
From: Youngstown Ohio
It's normal for secondaries not to open when "blipping" the carb by hand; there is no load really put on them. They will open, however, when you drive. You have to judge under driving conditions whether to alter their openning rate.
Burning Brakes
Joined: Jul 2005
Posts: 787
Likes: 0
The secondaries wont open for you to see; they open under load....wish I had a better explanation.
Holley floats can be reliable enough for a daily driver......I'd look at replacing the float and making sure the new one doesn't bind in any way thru it's swing.
Holley floats can be reliable enough for a daily driver......I'd look at replacing the float and making sure the new one doesn't bind in any way thru it's swing.
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
the vacuum reading you are stating, 17-18" at idle is manifold vacuum and it's irrelevent. True vacuum secondary carbs are controlled by Venturi vacuum, not manifold vacuum.
Simple reason why is the secondaries are suppose to open during hard accelleration and at WOT and that is precisely when there is virtually no manifold vacuum present. on the other hand, it's that same time of operation that you have the most air & gas flowing thru the carb and producing the highest levels of venturi vacuum which can than be tapped to open the secondaries.
You most likely aren't going to be able to get them to open by just revving the motor in your garage to test it out. As stated by the previous poster the motor need sa load on it for them to operate properly so you need to check them by driving and feeling for when they open. Turn off the radio and try to listen carefully as you may be able to hear the change when they open.
Simple reason why is the secondaries are suppose to open during hard accelleration and at WOT and that is precisely when there is virtually no manifold vacuum present. on the other hand, it's that same time of operation that you have the most air & gas flowing thru the carb and producing the highest levels of venturi vacuum which can than be tapped to open the secondaries.
You most likely aren't going to be able to get them to open by just revving the motor in your garage to test it out. As stated by the previous poster the motor need sa load on it for them to operate properly so you need to check them by driving and feeling for when they open. Turn off the radio and try to listen carefully as you may be able to hear the change when they open.
Safety Car
Joined: Dec 2005
Posts: 4,270
Likes: 20
From: Central Michigan
Did someone bend the float arm to adjust it? If so, the leading edge of the float is likely hitting the metering block, preventing the needle from closing. Ran into this with the last used Holley I bought.
Thread Starter
Pro
Joined: Nov 2001
Posts: 534
Likes: 6
From: Cave Creek AZ
Thanks for the replies - I guess my secondaries are working OK then - it sure seems to be running OK at WOT - you can feel a bit of a kick when you jump on it.
The float arm is not bent. The floats, needles, seats etc are all new. I have adjusted the float so that no fuel comes out when I remove the little window screw. We'll see how it goes... last week it started flooding after about a hundred miles of driving.
What is the purpose of the needle/seat, movement?
The float arm is not bent. The floats, needles, seats etc are all new. I have adjusted the float so that no fuel comes out when I remove the little window screw. We'll see how it goes... last week it started flooding after about a hundred miles of driving.
What is the purpose of the needle/seat, movement?
