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Old 08-20-2024, 08:01 PM
tooski tooski is offline
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Default Qjet pull off

Does anyone run with the choke pull off disconnected from the secondary air flap thus allowing the flap to open immediately instead of the 1 to 2 second delay? I find that when when I am in low and nail it, it takes about 1000 rpm before I feel the extra 'kick' from the secondaries. I recall seeing a vid of a Qjet operation in a drag race. It seemed to me the flap went wide open immediately on WOT.

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  #2  
Old 08-20-2024, 08:53 PM
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65 Lamnas 65 Lamnas is offline
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Quote:
Originally Posted by tooski View Post
Does anyone run with the choke pull off disconnected from the secondary air flap thus allowing the flap to open immediately instead of the 1 to 2 second delay? I find that when when I am in low and nail it, it takes about 1000 rpm before I feel the extra 'kick' from the secondaries. I recall seeing a vid of a Qjet operation in a drag race. It seemed to me the flap went wide open immediately on WOT.
Depends on your application, but I don't think you'll want to completely disconnect it....maybe speed up the opening rate. But if you completely disconnect it, you'll for certain need to tighten the spring some. If they simply flop open, you'll almost certainly have a bog since there is no immediate "pump shot"

There are a few tools and knobs for this. Depends on a few things, really. Weight of the car, converter flash point, if it's an AT, and the dashpot itself. Some can be drilled easily to shorten the release time. If your engine revs ultra-quickly, it may be necessary to disconnect it and just run on the torsion spring tension. You may have to play around with it a bit to see what it likes or wants.

Another thing to consider is your secondary air flaps and the location of the POE hole vs. the flap.

Late 60's and early 70's carbs have a slot in the flaps.

The late 70's 800cfm carbs have no slot in the flaps and the holes are actually above the flaps. Sometimes it's a good idea to expose those holes to the low pressure area below the flaps, so many times I'll create a slot to do so.

A fun trick is to angle the opening of the secondary discharge nozzles to create more exposed area....it gets the fuel flowing more quickly. Also, make sure the discharge nozzles aren't pressed in too far, restricting fuel flow. Many times they aren't positioned quite right.

  #3  
Old 08-20-2024, 11:17 PM
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Formulas Formulas is offline
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the plastic units have a brass inlet orifice at least they used to you can drill it out larger for a faster opening..

i want to say long time ago i tried it without the pull off because the dashpots i was drilling were almost instant so the next step was elimination

you can try it easy enough either it will bog or go i think when i took mine off i put more spring preload on the flaps

home depot advertises the small drill set for about 22.00
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Old 08-21-2024, 07:34 AM
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Do NOT disconnect the link from the pull-off up to the secondaries. I see folks recommending this all the time and it will not work. The pull-off is there to provide smooth transition and it must be timed correctly for this to happen. Problem is that dating back at least 20 years now the pull-offs being supplies do not have the correct springs in them nor the correct restriction in the orifice so they work correctly. Take the white plastic pull-offs currently being supplied for the early 67-70 Q-jets. The spring in them requres 14" vacuum to apply the pull-off, factory spec is 5"-6".

I've tried to get the manufacturer's to correct this issue but it goes on deaf ears. I used to modify them in house but currently sending them out to be "rebuilt" with the correct spring and orifice in them.

All the pull-offs I sell are modified to work correctly, next to nothing coming from the manufacturers is worth two squirts of duck poop right out of the box......



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Old 08-21-2024, 12:15 PM
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[QUOTE=Cliff R;6521709]Do NOT disconnect the link from the pull-off up to the secondaries. I see folks recommending this all the time and it will not work. The pull-off is there to provide smooth transition and it must be timed correctly for this to happen. Problem is that dating back at least 20 years now the pull-offs being supplies do not have the correct springs in them nor the correct restriction in the orifice so they work correctly. Take the white plastic pull-offs currently being supplied for the early 67-70 Q-jets. The spring in them requres 14" vacuum to apply the pull-off, factory spec is 5"-6".

I've tried to get the manufacturer's to correct this issue but it goes on deaf ears. I used to modify them in house but currently sending them out to be "rebuilt" with the correct spring and orifice in them.

All the pull-offs I sell are modified to work correctly, next to nothing coming from the manufacturers is worth two squirts of duck poop right out of the box......

Back in 70's, we use to disconnect the pull offs so we could get immediate secondary openings. I was told to do this by a co-worker who had a 69 RAIII GTO then. Sounded good at the time but it was bog city when stomping the gas during street races. We didn't know any better back then. Today, my Qjet was set up by you and operates as it should with no noticeable bog. The things you learn over the years can be rewarding if you pay attention!!

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Old 08-21-2024, 03:29 PM
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I'm using Cliff's pull off and I get a smooth transition to the secondaries without any hesitation/delay.

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https://youtube.com/shorts/gG15nb4FWeo?feature=share
  #7  
Old 08-21-2024, 09:22 PM
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Default Pull offs

I have 4 or 5 of these, are they any good?
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  #8  
Old 08-21-2024, 11:08 PM
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Originally Posted by yahooskidoo View Post
I have 4 or 5 of these, are they any good?
No.

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Old 08-22-2024, 12:37 AM
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Cliff's pull off:

https://youtu.be/QYmY885ALcI?si=uX59rPI1ABv3Jcst

It works.

That was just really short shifting to show the flap opening but it also shows that the pull off vacuum does work well.

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Last edited by jhein; 08-22-2024 at 12:46 AM.
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