Four Barrel Secondaries Question
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Four Barrel Secondaries Question
Hi everyone,
Have the Holley 390 on my Bronco apart for a stripped fuel bowl bolt.
This time while I had it apart, I noticed that even with the primaries completely closed, the secondaries had quite a bit of travel.
As far as I know, the secondaries aren't supposed to be able to open AT ALL if the primaries are closed.
For those that know carbs, are the secondaries (on the right) in these pictures opening too much? If so, do I need to bend the arm to limit their travel?
A picture of the primaries and secondaries completely closed. A lot of travel left.
Primaries and secondaries completely closed.
These three pictures are to show how far the secondaries can open on their own with the primaries completely closed. Seems like a LOT to me.
Thoughts? Is this normal? Or are these just able to open up way too much whenever they want? The vacuum secondary actuator does keep them stable, so they don't wobble around, but I wouldn't want them to be open while I'm just cruising down the highway.
Have the Holley 390 on my Bronco apart for a stripped fuel bowl bolt.
This time while I had it apart, I noticed that even with the primaries completely closed, the secondaries had quite a bit of travel.
As far as I know, the secondaries aren't supposed to be able to open AT ALL if the primaries are closed.
For those that know carbs, are the secondaries (on the right) in these pictures opening too much? If so, do I need to bend the arm to limit their travel?
A picture of the primaries and secondaries completely closed. A lot of travel left.
Primaries and secondaries completely closed.
These three pictures are to show how far the secondaries can open on their own with the primaries completely closed. Seems like a LOT to me.
Thoughts? Is this normal? Or are these just able to open up way too much whenever they want? The vacuum secondary actuator does keep them stable, so they don't wobble around, but I wouldn't want them to be open while I'm just cruising down the highway.
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From: Lost
The way the secondaries work is the flow thru the primaries creates a vacuum to open the secondaries, therefore, they shouldn't be able to open while just cruising. Unless the primaries are nearing peak flow, there won't be enough vacuum to pull the secondary pod open.
That's more free travel than most I've seen, but shouldn't be an issue.
That's more free travel than most I've seen, but shouldn't be an issue.
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From: Boise, Idaho
Yeah, they're completely controlled by vacuum, but if they were completely secured by it, I don't think there'd be a need for the limiter bracket shown in picture 1. It's currently allowing the vacuum from operation to pull the secondaries further open than the primaries.
My thoughts on it, doesn't necessarily mean I'm right.
Just to be on the safe side (since that seems like it could greatly affect MPG, which have been an issue), should I bend the limiter to make sure the secondaries can't open at all when the primaries are closed?
My thoughts on it, doesn't necessarily mean I'm right.
Just to be on the safe side (since that seems like it could greatly affect MPG, which have been an issue), should I bend the limiter to make sure the secondaries can't open at all when the primaries are closed?
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From: Lawrence Swamp
My YF rebuild had a lill' sheet of directions (for a real mechanic to use). It gave measurments for almost every operation of the carb: "Push this to here, measure, return to former position, measure. Difference should be xx. Bend tab xx to achieve that measurement." U might benifit from similar proceedure if U can get those figures (from the co., as it seems U R in the process of aquiring).
my .02$
Good luck, I know YOU will get YOUR Qs answered n B back on the rd!
my .02$
Good luck, I know YOU will get YOUR Qs answered n B back on the rd!
Last edited by chrlsful; Mar 2, 2010 at 10:09 AM. Reason: spelling
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