John Osborne Performance

Larry:

There's no mechanical link connection between the primary pull-off and the choke. It only affects the secondary opening rates. Only the rear pull-off has any connection to the choke control.

 

The link or connection you must be referring to is the vacuum break rod bumping into the tang of the vacuum break lever as best I can make out. It wouldn't work without the vacuum break lever or rod, so nothing can be missing. I've always found that if the correct rods are in place, both vacuum break rod (secondary control) and the choke rod (primary choke door), once the engine starts and you have the 1/8" or so of clearance (adjusted into it) the vacuum created under that door will pull it open and then the secondary pull-off with its delayed affect will gradually pull it open even more to keep it from loading. I get too literal at times during a description (just the nature of it I guess) but now understand what you're referring to. Getting the gray matter in action during this graveyard shift is murder!

 

Hey all carb guru's
If I found a guy who will rebuild Qjets for $80, do you think he is lying, is there some important steps he must be leaving out for that price?

 

I think he just throws a gasket kit in them. Hell I can do that. Ask him if he rebushes throttle shafts or calibrates for you r exact application. If he says HUH? walk away.

 

For just a quickie rebuilt with a kit, float, primary and secondary pull-offs and filter you'll have $60 invested. Which leaves you $20 to do the rebuild and all the other necessary things to do it right. Add in rebushing the throttle shafts and sealing the well plugs for whatever that may cost you in time and materials. Then you have to disassemble, clean, glass bead and recolor........what's that time worth? And then if necessary the subject of changing jets, primary and secondary rods, power piston and the hanger, all of which are not cheap. To spend $250 to $300 is a bargain to get one done. While the performance is number one in most everyone's book, to get the small parts yellow cadmium plated is also time consuming and expensive. Its not unheard of to spend upwards of $400 to $500 for a complete show and performance oriented QJ.
As Dave said, anybody can throw a kit in one......but you get what you pay for.

 

I went out and tested the primary pull-off function of opening the choke door upon startup. The vacuum acting under the choke door from the venturii opens the choke door before the rod hits the tang and opens that door. So it would function as described in the manual if the diaphragm acted quicker. All the links and tabs were adjusted correctly. I tried a new AC pull-off and an aftermarket version. The secondary or auxillary pull-off does open it further once it takes effect and the engine is running. Just thought I'd clarify that point.

 

Heres what he answered: When I rebuild them, I disassemble, clean every nook and cranny, reassemble, checking all measurements as I go. I usually don't mess with calibration, due to so many different set ups.

Apparently he should be calling it cleaning carbs.

I really just need a kit thrown in, my car is a driver. But it sounds like he doesn't even do that. I probably wouldn't have much done to mine at all if it wasn't for the fact I have to pump it up with the gas pedal to get gas in it to start, probably due to leaky float?

 

Most likely your primary and secondary well plugs are leaking. That along with sloppy bores for the throttle shaft are the two most common problems we have with the QJ's. Not to discount the non-working pull-offs and misadjusted secondary upper door spring tension. I use MT-13 to seal those wells. The key is getting everything clean. That's why after soaking in carb cleaner I glass bead everything, it can't get much cleaner for the epoxy to stick and seal. And recoloring is just part of the deal after that. It just never seemed right to send a carb back that looked like all that was done was a kit was thrown in it. As Dave said earlier.............anybody can throw a kit in one.

 

You may have found that the choke door needed just a little more clearance so it would get the needed air to run smoothly till the secondary or auxillary pull-off took effect.
I used to run a very good modified 800 QJ on my blue car (with the old 118 cammed engine) and never used the front pull-off, or a choke. I adjusted the secondaries solely with the sec. windup spring. That was by far the best QJ I had ever used. It had several internal passages drilled out and just did everything I wanted. It would run practically neck and neck with a #4781 Holley 850 in both et and mph through the traps. But the QJ would smother the Holley in miles per gallon.

 

Dave,

Not to get into a peeing contest, but Larry is right on the control of the primary choke pull-off.

On your QJet, if the choke blade is pulled off initially only by the airflow of the engine, I would think your choke coil spring is weak or needs adjusting. If you were to run that carb/engine during a cold winter (say on a daily driver), you would likely notice a lean hesitation because the choke comes off too fast. Remember, there is a fair amount of tension called for in the choke wind-up. If the tension is correct and the pulloff is bad, the engine is guarenteed to load up on a cold start or something else is wrong! We used to buy primary choke pull-offs by the case..

I was an engineering student at Rochester Products from 82-87, and then went into the service industry and had to make QJet equipped daily drivers start and run like FI. An impossible task sometimes, but the most critical and finicky adjustment was by far the primary choke pull-off.

If you recall, the later QJets had an adjustment screw on the primary choke-pulloff, which was a lot nicer than having to bend the rod. It is also noteworthy that most QJets produced (not Buicks, of course) only had 1 choke pulloff. The rate of opening was dictated by the application.

HTH's

 

If John is going to quit doing the QJ's we(I) are in trouble! I just don't like Holley's on a street car.Mike D.

 

I have had a lot of experience with Q-jets since 1967 and still work on them . But if John is still working on them I will not take on any work from the board . Until I hear it straight from John himself , I will stay in the shadows .

 

Bob,
No peeing contest, not to worry. The open dialogue and exhange of information is what this is all about. Anytime we can gain knowledge its a really good thing. None of us knows it all and all of us have something to gain from others.
I mispoke when I said there is no direct link or connection. ou: The secondary rod does bump into the tang on the choke control. Its just what does what first.
Correct me if I'm wrong, but to clarify what I've found to be happening. The initial movement of the air door is affected upon by the vacuum under that door just before the pull-off affects the rod that pushes on the tang or at least thats been my experience.
Whereas it should be affected upon first by the pull-off.... There is a built in clearance by measuring the distance from the air horn wall to the lower edge of the door. The pull-off almost immediately then also pulls the rod back towards the tang and also pushes the door open. Then the aux. pull-off comes into affect pulling it open even more. I can sure understand the tension on the linkage from the coil in the manifold and not allowing the initial response be from manifold vacuum but from the front pull-off. Very good point. I've just never had a problem with loading on any of the QJ's I've done, and its been more than a few.
Where we live, a working choke is paramount if you drive year around. So having a working bi-metallic spring in the manifold is necessary for the tension.
I remember the various front pull-offs with varying orifice sizes and links tailored to specific applications. And I suppose the spring tensions also varied. Filling the tip and redrilling the orifice to fit has been done for years as you know, and allowed fine tuning as necessary.

As for the ability for more than one person to do a QJ correctly. Lot's of people can build these carbs right, just seems everyone is afraid to step on toes and mention anyone elses name on this board.

I've enjoyed playing with these carbs in both performance and resto. modes for a lot of years. But its low key word of mouth stuff and I certainly wouldn't want to take anything away from someones livelihood. Its just a hobby for me and I enjoy doing them with time permitting. I have a job that pays the bills.

I've known John for many many years. Always a first rate guy in anyone's book. Years ago while at the Nats in Bowling Green I was pulling the 400 trans out of the TA wagon to swap gear sets (before Mike switched to a Lenco) with John giving instruction while on a pair of crutches after he broke his leg. Don't go flushing your QJ's down the drain if John quits doing them. Its not rocket science, you guys can do it. And with this forum any questions can hopefully be answered for a good result.

 

Dave I think you and I are on the same page about the carbs . I enjoy working on them and will help anyone with theirs BUT as I said before as long as John is making a living working on them I will not take on any heavy amounts of repair on them . I still have some experiments I want to do to try some different things with them . When set up right a q-jet is a great carb when used in the right environment . I would just about be willing to take the injection system off my 454 dually and use a Q-jet .

 

Go ahead guys. Keep in mind, it is a different thing to give free advise, than to charge money for it! Good Luck!
As soon as I get time, I will start posting parts for sale. I will post one of my GS's and my T-R.

 

Apparently then, I am missing some works on the side of my carb. I have a primary pull off and that's it. It works great and has the correct 72 #s though.

 

Wow, uzzled:

 

John,

Is their anything that can be done to prolong the life of existing good "primary choke controls" on a carborator? Generally how long do they last in service?

Les