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Discussion Starter · #1 ·
The link off the throttle that controls the “release” of the secondaries is in the secondaries slot to retain it prior to the vacuum secondaries coming into play. I’ve found that taking up all the play in the link to slot helps retain secondary throttle plates in position prior to throttle release off of idle.
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Without it bottomed in the slot the secondaries have play. Is anybody “adjusting” this link? Out of the box they seem to be all over the place. Sure it makes a difference if you have the transition slot opening correct at .040” or less. It’s like the accelerator pump, adjust it after throttle position is set. My friend was having all kinds of stumble and his link had 1/8” gap. Closed it up gap and stumble gone. I didn’t witness it but I believe him.
 

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What gap are you talking about? When looking at my Quick fuel carburetor the secondary link sits all the way back against the secondary throttle shaft in the closed position like it does in the photo. Now on a Holley brand vacuum secondary carburetor in the closed position the linkage has about a 1/8 of an inch or so from making contact with the secondary shaft in the closed position. My question is all of my quick fuel brand ones are all like your photo ones but the holley ones are not. Now I have have my holley carbs adjusted before on the secondary side using different springs and If I used the right spring and shooter combo I never had a stumble if setup right without having to change the rod linkage to where it makes contact at the idle position.

Is what what your talking about and if his had a gap to where *** would not make contact like yours in the closed position how in the world did he change that? Or am I misunderstanding this. You have me mighty interested in this and maybe it might be a new thing one can do to improve on the secondary opening of the vacuum secondary. I myself have come to not be to thrilled of the holley design to where you can only swap out springs with there quick change pod as it never give you the adjustability range you want and to fine tune and the quick fuel adjustable pod with the screw allows more precision to tune it better.

The holley pod has a .040 brass restrictor in the hole that feeds the top part and by changing springs that was all you can do and it will vary by engine but you can't really get more out of it. I took my holley pod and drilled the .040 brass restrictor hole in the pod up to .060 to allow more signal to the pod but now it seems on my engine its too much with the purple spring as it stumbbles for about two seconds before the secondary boosters start to flow and the shooter and pump cam size is spot on for what my engine needs. Before I enlarged the pod restrictor it did not do that but I read about an article in Hotrod magazine to where they drilled out there pod to .055 to get better response out of the secondary.

I figured it would be worth a shot. Now on the quick fuel pods that are adjustable they have not brass restrictor in them and the hole measures about .075 give or take a little and with the adjustment screw it allows you allow the amount of air signal coming into the pod to slow down or make faster the opening of the secondary pod using what ever spring you want. I am going to take my pod off and drill out the brass restrictor the rest of the way open and swap out to a quick fuel adjustable pod to get rid of this stumble. I had a white spring in the holley pod before I drilled anything out and it worked quite well with slight sumble but nothing bad so then went to a yellow and it did fine but I did not want them to open up to quickly so went with a purple but it was not quite as good as I wanted so did the slight enlargement mod of the brass restritctor and I think it made it to big by just a hair.

On my previous carb with all things the same except one air bleed size difference in the rear but using a quick fuel pod with a purple spring and adjusted it correctly with a purple and yellow spring it would work fine with no stumble.

I hope you can shed some more information on what your talking about as maybe I am dumb but I am kind of confused on the way your describing it but would love to try this mod once I understand it more. I have extra linkages around to try and stuff. Thanks for sharing your finding on this.
 

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Yep, I always check it, frequently needs to be bent a little longer to make sure it closes the secondary .

Worse yet is the guys who put a screw in the slot on the other side of the link, using the link to force the secondary OPEN, using that link to yank them open when the primary moves far enough .....because they are clueless about how to actually set up a vacuum secondary Holley. Typically makes a huge bog that way.
 

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Discussion Starter · #4 ·
Eric x2 yes, the link has to be bent to fit correctly fully bottomed out in the secondary shaft curved slot. Just as in my photo. If one fails to do this be it a Holley or Quick Fuel the secondary throttle shaft can “rattle back and forth” against it’s stop adjustment screw and any pot lower pin slop. I presume this is not intent. And the comment that many Holleys are like 1/8” or better gap, for what reason? I have never seen any tech articles nor discussion about this link and it’s close fitting with the end of the curved slot. I have always flattened out the link a bit to fit snug with the end of the slot. This is final setting because the primary throttle shaft has to be in the position you want it or else you will be doing this setting again. Similar to the accelerator pump adjustment has to be after final throttle shaft setting.

Yes, I also prefer the Quick Fuel adjustable vacuum pot. Quick Fuel has a number of features that put it in modern times.........
 

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Ok guys I know this sounds dumb but what how in what way do I bend the linkage arm to get it to bend back far enough to look like that in the picture above? I have like 13 vacuum secondary carbs sitting at the side for spare parts and other stuff and things to tinker with and that is something I have never seen or noticed before. This is some excellent news and want to fix mine. Do I just leave it hooked up and take a pair of pliers and grab the outside of the linkage and force it back?
 

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Discussion Starter · #6 ·
Remove the link, set it in your vise and squeeze down to take out a bit of the curved section. That will make it longer between the two ends that connect the throttle at both ends. Do not go much in the vise it comes on fast. Test fit and trial fit again, repeat as necessary.
 

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Thanks 57 nomad I will have to give it a try. I have noticed that some of my Quick fuel carbs are already correct and some are not and all of my Holley ones are not back all the way. I would have never noticed that before. I don't know how the secondary side would flap around while in operation as I have always just seen them in a smooth motion but I do notice that if you have wide open throttle at times it will stumble like blubber a few times until the secondary boosters kick in. Its to bad the vacuum secondary could not be a little bit better like how a Qjet does or a Edelbrock AVS operates without the need of a vacuum diaphragm type of a deal but its not bad once its correct but its the point to get the best out of it without being to much that is the hard part without having to use a heavy spring which defeats the purpose of the secondary side if you want performance out of it.
 

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Ok one last question when I put the link in the vice do I stick the long part that hooks into the front linkage in the vice and the curved part sticks out and then I proceed to bend the curve part of the linkage back some with it sticking straight down into the vice? Sorry to sound dumb here I just want to put my link in the right way in the vice as I look at it and then think I would stick it with the part that goes into the primary linkage straight down towards the floor with the curved area sticking up straight towards the ceiling and then slightly taking a pair of pliers and then slowly bend the curved area back until it would make contact with the back lever like in the above picture. Is this correct?

Sorry I just don't want to bend my linkage the wrong way and end up having to replace it if I weaken it and brake it by accident.
 

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Discussion Starter · #9 ·
It sounds like that will work. But I do not use pliers only the vise. With the link in vise the short leg with hole for the pin is pointing straight up. Vise against same leg, while also against curved leg and against the other short leg with the longer 90 degree leg. Vise jaws will be contacting three places so when you tighten vise it squeezes the curved area thus opening up the curved area and the result is lengthen distance between the two short legs.

Your method with pliers will work but hard to tell how much you bend it. Where as in the vise you see the metal move.
 

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I typically just use two solid sets of pliers.....you can even do it without even taking the link off if you've got strong hand grip, but it is easier for a first timer to probably take it off.

The mechanical secondary "double pumper" carbs have a similar link arm, just in a drastically shorter slot on the secondary shaft only about 3/16" long slot.....you bend that link to ensure the secondary blades go fully vertical at WOT.
They have a throttle return spring around both shafts that ensures full closure.

I remember reading somewhere that the vacuum secondary pod spring is supposed to be responsible for holding the secondary's closed against their stop and the link's job is just to push it off WOT down to nearly closed when getting off the throttle.....but if you don't confirm the link "double checks" it fully closed you can have a carb that won't return to the set idle speed and be inconsistant about it.
Doesn't change full throttle any, or anything like that, no more power...it's just an idle speed stability thing.

Once you've had it bedevil you, you never fail to check it on every carb after that, after figuring it out.
 

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Well I might not have 24 inch pythons like Hulk Hogan but I do have a measly 12 and a 1/4 inch garden snakes for arms and I think I should have enough strength in my mini hands to do the job lol if I can give anyone a laugh but all things aside Ericnova72 how do you do it with the pliers without taking it off and I think I would wrather go that way if I can and just go through all of them and be done with it. I even tried last night and tried to bend down on the rear lever part but it just bent the rear bar down without taking out the middle part to bend back.

For the vise part I am still trying to get it into my dingy head how that works as when positioning it so it will make the front part of the lever that goes on the primary to stay straight while keep the back part straight and to allow it to make the middle curved part to go backwards to allow it to keep the throttle closed once letup on wide open throttle.
 

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Well I might not have 24 inch pythons like Hulk Hogan but I do have a measly 12 and a 1/4 inch garden snakes for arms and I think I should have enough strength in my mini hands to do the job lol if I can give anyone a laugh but all things aside Ericnova72 how do you do it with the pliers without taking it off ....

In the picture 57Nomad posted, see that shiny section on the link?? Between the hairpinned link end and the large bend it maked upwards?
Facing the carb just like you are looking at the picture,
Grab it right there with one set of pliers in your left hand, with the handles pointed right back at you. You are grabbing the link crosswise in the jaws.
Next, second pair of pliers in your right hand, handles pointed right back toward you again, but rotate them 90° and grab the link above the large bend and before it goes into the slot on the secondary throttle shaft.
Now twist your right wrist, to "unwind" that large radius bend in the link just a hair as needed.
You got to have decent wrist strength to do it. Not terribly hard though.
If it's something I'm doing on the bench I'll take the link off just to make it a little easier.....but I'f I'm asked to help straighten problems out on someone's car, or tuning in a new set-up on the motor I'll just bend it right there on the carb.
 

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Thanks ericnova72 for the instructions and I will try that method but I want to try the vice as well but my question is when doing it in the vice way does the linkage matter what direction its facing? Does the part of the vice that is moving in have to be on a certain side of the linkage or does it matter as long as its in the direction like the link sticking straight up like stated but on my vice the part that pushes in with the link sitting straight up like 57 nomad said it would be hitting the top of the linkage curve with it facing me like in the picture removed, and it would be sticking straight up in my vice and I would turn it and the vice would be tightening up on the back aka the top part of the curve.

Hopefully my vice is big enough to fit it right as its just a small vice. I don't know if I would have enough wrist strength or not but I will try. Worst case I can't get it by my wrist strength which is quite weak since I discovered I have small fiber nerve neuropathy last week and that is why my body has been declining really bad the last several years from my cancer treatments to my head and neck back in 2012. Will give it a go and post back how it goes for me. Thanks to both you ericnova72 and 57nomad for sharing this information. I will add it to my notes of carburetor stuff and can't thank you guys enough for all the years of helping out so many on here and me.
 

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Eric 32, I just checked mine and sure enough there was an 1/8" gap. I took the link out and tried the vise method. OOPS too far, OOPS not enough, etc. Finally I just it installed then got 2 pairs of pliers, grabbed the horizontal part of the shaft with one set in my left and the part of the shaft that heads vertical to the secondary throttle with the other set with the right. Both sets of pliers as close as you can get to the bend. Then just hold the left hand and twist the right hand. It bends surprisingly easy. I don't think you will have any trouble. You can position the pliers to gain leverage.
 

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Jaw22w I myself today went to check my vacuum secondary pod on my engine and I was wondering why my carb would bog when I thought I had it setup just like a previous one minus just a .004 size difference in the primary idle air bleed and could not understand why my carb was bogging. I knew my plugs needed changed as they were one step colder then what I normally use and I on my previous carb had the needle and seats stick on me from the carb sitting during the winter months and they got varnished up so I sprayed them with carb cleaner and then some silicone spray and all was good again.

I then went out to see why my vacuum secondaries were seemingly opening up to quickly and I thought I had a purple spring in my pod and my old eyes these days its getting harder to see tiny things and I have my springs put into bags separate by color and I thought it was a purple spring and lough and behold it was a white spring lol as I knew my pump shot was correct and adjusted right. I then drilled out the brass restrictor in the pod and stuck on a Quick fuel topper so I can adjust the opening rate now to what my carb needs and I then remembered this post and sure enough I looked at my carb and it had the famous 1/8 inch gap on it and I noticed when my secondaries would open up it gave me a flutter feeling and on one of my previous Quick fuel carbs I had on a few years back I noticed the linkage on it was all the way back like it should be like in the photo above and it never did that.

Even with a correct spring it would sputter at certain times and it would never go away regardless what I would do with it. I am going to try the pliers thing and see if these tiny old hands can bend them right. Hopefully I wont bend it wrong. I might have an extra around if I do. I can't believe Holley would do that with there carbs and if the vacuum diaphragm would rupture and with out the primary throttle holding that back it would make for an erratic idle that is for sure.
 

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Discussion Starter · #16 · (Edited)
Eric here is photo of the link in my big vise (overkill), the squeeze comes on fast so go slow.
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And here it is all done and installed on my Holley 3810 for my 67 Corvette.
Just need to put the pin back in the hole.
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Just as a side note before I adjusted the slop out the idle was poor. Instantly it is where it should be at 650 RPM’s and smooth. Adjustment 2 corner idle screws out about 1 1/4 turns. T slots are square and secondary T slots not showing.
 

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I was able to just use one pair of pliers and bend my linkage back no problem. The pliers I used were a big thick pair and pretty long so gave pretty good leverage with just hardly turning it with my hand. I just bragged it on the curved part on the outer side and slowly turned my hand clockwise and held my throttle linkage with my left hand and just a little turn and it was done.

One thing I did figure out though is before you go bending that linkage all the way back to take out the slop I think the reason Holley does not put them all the way back is because once you bend it all the way back to keep the secondaries from opening up anymore if you need to open up your secondary side to allow more air in to keep your primary throttle closed enough to have a proper transfer slot exposure to where it is square, you will need to bend the linkage back forward just a hair until you get it to where you can adjust it again.

I just figured that out while going through my stand by carbs I have at the side for parts etc and I went through a few of them and it dawned on me that if I bend them all the way back and if I need to open up my secondary side more I can't do it without having to bend the linkage back forward. So I bent half of my carb linkages without thinking of that until I moved it with my fingers to see if the slop was gone and then it went through my mind if I did not have enough secondary opening then I have to bend it forward again. Because once you have it all the way back and if you need to go a quarter of a turn forward your not going to be able to.

I think you can maybe get a 1/8 of a turn on the rear screw before it would not want to adjust anymore. So make sure before you go bending the secondary linkage on the rear make sure your carb idle is setup correctly on both sides first before bending the linkage. Thanks 57nomad. I just went ahead and fixed it on my truck so it should not flap around anymore.
 

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Sounds pretty good on your idle mixture screws and stuff and hopefully you can get your carb tuned well. Looks like you have the quick fuel base plate on a Holley 3310 style main body and I am assuming from the photos as the main body I can tell is a pretty old one by the support ribs in the casting has the really old style like the very first 4160's they made in the 70's and early 80's. I had a few 600 Holley main bodies of the very first 80457 and 1850 where the main body had that side part like that before they added more material and more bracing for I am assuming to help against warpage like they later added the brace across the metering blocks to help against warpage as well.

I just looked up that number and I found out its a 67 carb that was on a Corvette but I don't know what cfm rating it is as I just did a quick google search but I am assuming it looks like a 600 but I could be wrong.
 

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I went back through looking through my carbs and in case anyone looks at this thread in the future I found out that if your linkage is not back correctly to eliminate the slop and to close the 1/8 inch estimate gap that is normally there, so you can still adjust your secondary and not have to keep adjusting your linkage I learned that if you open up your secondary throttle at exactly half a turn and just a hair more and you bend the linkage back to take out the slop, you can then back it off to a 1/4 to near 3/4 of a turn and the linkage will still be tight and allow just enough movement to adjust your secondary linkage to allow a proper idle setting on the primary side if your carb and timing is setup correctly and your secondary side will not have the slop anymore and the secondary throttle plates will then open up all the way and as soon as you let off the throttle at wide open throttle it will snap back all the way with out flapping like they can do with the gap in the linkage.
 

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Here's a little story. My buddy drove his brand new 1968 Bronco (beautiful piece) to my shop today, timing his visit in between rain storms. No top on the Bronco!. He wanted me to adjust his carb a new QFT SL450VS. I got it all adjusted for him, then noticed the infamous 1/8" gap in the secondary linkage. I told him what I was going to do. He said go for it, so I grabbed come pliers put just a very little twist on it, and it broke at the bend. Well CRAP! Of course I didn't have a spare, and I didn't want to take one off one of mine. I'll just TIG it back together. It took some doin' to get it clamped together in the right position to weld. Since I was taking so long to do a little carb adjusting, Of course the down pour started. There is no room in my shop for another car. We tried to cover the interior, but it was too late by the time I got out the tarps. So we had to wait on the rain to stop. Butch wasn't real happy about that. Anyway I got it all in and adjusted and as everything was already wet, he took off in the rain. LOL
That link broke with way less effort than it took to adjust my other 2 QFT carbs.
So, just a little warning that it can happen.
 
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