Q-Jet Secondary Adjustment
Thread Starter
Drifting
Joined: Feb 2005
Posts: 1,583
Likes: 5
From: Richardson Tx.
Q-Jet Secondary Adjustment
hi - My Secondary throttle blades are rotating just past 90 degrees when I open up the throttle all the way using my hand. I noticed in Lars' t-shooting article that its recommend bending the Primary throttle tang.
Is this the tang that is closest to the carb body and eventually makes contact with the flat surface of the carb body? I am guessing that the point is to make the tang hit the flat spot sooner (to keep the secondaries from over-rotating)
If so, I noticed that if I were to do this adjustment then the Primaries would then stop before 90 degrees as a result.
Can you lend some advice on this?
thanks Rob
Is this the tang that is closest to the carb body and eventually makes contact with the flat surface of the carb body? I am guessing that the point is to make the tang hit the flat spot sooner (to keep the secondaries from over-rotating)
If so, I noticed that if I were to do this adjustment then the Primaries would then stop before 90 degrees as a result.
Can you lend some advice on this?
thanks Rob
Melting Slicks
Joined: Mar 2006
Posts: 2,465
Likes: 0
From: Orange Park Fl
First off, if the throttle blades open just slightly over 90 degrees (5 degrees or less), that can be a good thing on a Chevy engine to avoid leaness in ther forward cylinders (see "Rochester Carburetors" by Doug Roe, pg 139-140).
Second, Lars is the man, but you may be misunderstanding his directions. You really do not want to bend the primary to secondary actuating rod to adjust blade angle.
Usually, if the blades open more than 90 degrees, it was an intentional modification. If they did it correctly (as described above), leave it alone!
God bless, Sensei
Second, Lars is the man, but you may be misunderstanding his directions. You really do not want to bend the primary to secondary actuating rod to adjust blade angle.
Usually, if the blades open more than 90 degrees, it was an intentional modification. If they did it correctly (as described above), leave it alone!
God bless, Sensei
Melting Slicks
Joined: Sep 2010
Posts: 2,414
Likes: 59
From: Emerald Isle NC
You should get a friend to actuate the carb using the accelerator pedal as you observe the secondary throttle plates. Often, you can open them more by hand than your pedal will allow. Lars re-did my carb after a bad rebuild. Using the above method, the secondary opens to 90*. If over opening was preferred, I think he would have adjusted it so. There's a reason the guy's a q-jet legend...
Thread Starter
Drifting
Joined: Feb 2005
Posts: 1,583
Likes: 5
From: Richardson Tx.
My throttle plates are going past 90 deg so I'd prefer to get them back to under 90 per Lars.... Lars provided this pic to show me the correct Tang to bend. I think that the logical way to bend this would be towards the other tang on the right....but I wanted to make sure before I do it.
Do I have this right?
Do I have this right?
