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-   -   Qjet pull off (https://forums.maxperformanceinc.com/forums/showthread.php?t=875606)

tooski 08-20-2024 08:01 PM

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.

65 Lamnas 08-20-2024 08:53 PM

Quote:

Originally Posted by tooski (Post 6521630)
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.

Formulas 08-20-2024 11:17 PM

1 Attachment(s)
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

Cliff R 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......

http://forums.maxperformanceinc.com/...1&d=1724239969

http://forums.maxperformanceinc.com/...1&d=1724240003

Ram Air IV Jack 08-21-2024 12:15 PM

[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!!

jhein 08-21-2024 03:29 PM

I'm using Cliff's pull off and I get a smooth transition to the secondaries without any hesitation/delay.

yahooskidoo 08-21-2024 09:22 PM

Pull offs
 
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I have 4 or 5 of these, are they any good?

65 Lamnas 08-21-2024 11:08 PM

Quote:

Originally Posted by yahooskidoo (Post 6521844)
I have 4 or 5 of these, are they any good?

No.

jhein 08-22-2024 12:37 AM

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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