Secondaries aren't opening on my 1976 carb I rebuilt...

Discussion in 'The Venerable Q-Jet' started by berigan, Oct 24, 2021.

  1. berigan

    berigan Well-Known Member

    Can find a ton of info on bogging issues, but that's not my problem (never really have dealt with that) I bought a 1976 Electra about 2 months ago. best starting car I've ever owned! Seriously! But, after awhile, it was starting to idle rough, and then at higher RPM's. Car sat for a long time, so I knew I'd need to rebuild it, accelerator pump, the float needle had to be worn out. But wait, while it's a 17056240, I had purchased a carb and intake from someone here in 2017 that I was going to put on my 1977 Regal (2 barrel) that was from a 1976 Buick with practically the same carb number, 17056244! (long story short, Never swapped the 2 barrel for the 4 , a "Friend" that was going to help me-- even insisted I get the intake magnafluxed first, backed out of helping me, and I can't lift intake(s) myself with my lousy back)
    so, for 4 years, I have had my rebuilt carb sitting on my dryer (with an chrome air cleaner on top of it-can you believe I'm not married? :p ) and since I can't keep the Regal and the Electra , I thought, hey the rebuilt one even had new choke pull offs in place, and I knew the rear one on the carb on the car was shot, a true no brainer, just swap them!
    So I did. Everything seemed great (choke wasn't set perfectly like the original one, still need to work on it) seemed to idle ok, a slight vibration in park, but oddly, not in drive. Took it out for a drive, and smooth, torquey but no secondaries at all!
    This was the first time I ever rebuilt a q-jet that wasn't already on one of my cars, so I of course don't know how it ran previously, but didn't look like a cobbled together carb, or one that was beat up.
    I've rebuilt q-jets off and on since the 80's and don't recall having this issue before. I was comparing the 2 carbs everything looks exactly the same, everything seems to move freely on both (oh, I did forget to mention that the rear mounted choke pull off that I got brand new from a name carb shop, is somehow shot) My Dad kept saying, well, that's your problem...I'm sure it's a problem, but the original carb , it didn't work either, and the secondaries opened just fine. Also, are the back ones hard to find now? checked at 2 stores online, and they didn't seem to have one for 76's
    thanks....
     
  2. dan zepnick

    dan zepnick Well-Known Member

    The secondaries won't open when the choke is on. Look behind the choke,you can see the lever type piece holding secondaries closed.might be stuck??
     
    berigan likes this.
  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    The secondary choke pull off just opens the choke blade during cold starts. It has a delayed effect unlike the primary choke pull off that opens the choke immediately. The secondary choke pull off is unimportant compared to the front pull off. The front pull off does double duty. Not only does it open the choke blade upon cold start, it also holds the secondary air valves (not the throttle blades) closed until the engine can handle the additional air flow. The secondary air valves are the important factor on whether the engine bogs or not. Proper adjustment of the air valve spring wind up, and the front choke pull off are very important for seamless transition from primary to secondary operation.

    If the secondary throttle blades aren't opening, that is a linkage problem, or as mentioned, the secondary lock out lever that operates when the choke is on.

    For any Q-jet parts, I recommend Greg Gessler at,

    https://quadrajetparts.com/rochester-quadrajet-c-128.html?osCsid=8cdc3c474038e8114b24f4f02925f6c2

    https://quadrajetparts.com/quadrajet-pull-offs-c-128_32.html
     
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  4. techg8

    techg8 The BS GS

    secondary throttle blades not opening?
    1) secondary lockout lever engaging (should only engage when choke is closed)
    2) secondary blades possibly hanging up on the basegasket?
    3) secondary actuating linkages in need of adjustment? The top end of the link should contact the secondary shaft arm when the links lower curve is midway in the shaft arm slot.
    4) is the secondary shaft excessively loose in the baseplate? this can cause misalignment problems that contribute to blades jam up.
    5) check the secondary shaft springs, make sure they are not broken , missing or incorrectly installed

    Secondary air valves / flaps not opening?
    1) check that the secondary throttle blades are opening.
    2) incorrectly adjusted secondary link from primary pulloff can delay valve opening if set too tight. adjust link so the valves can move .060" when the pulloff is fully actuated by vacuum.
    3) on some air horns with significant warpage, the air valves can jam in contact with the air horn. adjust their position or file the air horn.
    4)check your secondary air valve windup spring tension. wound too tight, it can delay and or inhibit valve opening.
     
    berigan likes this.
  5. berigan

    berigan Well-Known Member

    Thanks guys! I'll check those suggestions out later today. Found the correct rear pull off, and ordered it.
    Speaking of that rear pull off, that would likely be a vacuum leak, correct? Or would there need to be a crack in the metal, and if "just" the diaphragm was shot, you wouldn't lose vacuum? Wondering if the bad one on the old carb was part of the reason I was only getting 9 MPG . I Know, a low compression 455 in a 4800 car isn't going to get great mileage, but I got 11 MPG out of a 1971 Coupe De Ville , and saw someone say....somewheres that they were getting 14 MPG on their 76 Electra, before an issue brought it down to 11
     
  6. Cliff R

    Cliff R Well-Known Member

    The rear pull-off isn't needed on that carb and a waste of time/funds to install it. I don't like them because most have a tiny vent hole in them to delay operation since it's only there if the front one fails anyhow. The vent hole also makes them fail a vacuum test during testing plus it will pull some unfiltered air into the engine which isn't a good idea either.

    If you fuel mileage is clear down at 9mpg's you have fundamental issues with the carburetor and overall tuning of the engine, assuming it's in good shape otherwise.....
     
    berigan likes this.
  7. berigan

    berigan Well-Known Member

    I'm just beyond frustrated right now never had so much trouble with a Quadrajet , and now it's with 2 quadrajets. The one I had rebuilt 4 or 5 years ago as I mentioned above I didn't know the history of it it was just attached to the intake I bought and after installing I notice it was leaking gas slightly at the top up front (I try so hard to not overtighten, to the point of having leaks that I do have to tighten to stop) and whatever I tried to do I could manually Force open the secondaries on the air horn (sadly I bought yet another pull off before seeing Cliff's comment above) didn't see anything that was binding in the choke mechanism or on the throttle side( no lockout like earlier q-jets I had, I can push the top of the secondaries down while its running, but it takes some effort, but can't compare to other cars as I never did this before) but it seems like no matter what I tried couldn't get the secondaries to open maybe they tipped open ever so slightly cuz it still seemed certainly up to 30 or 40 pretty quick. As my Dad would say though, 2 barrel cars are pretty quick up to 40.
    But I decided quit messing around with the carburetor that no doubt had many more miles on it, and probably needed bushings in it, why not justrebuild the one that was on it originally?
    so I ordered a kit the complete kit from Cliffs and went about rebuilding it. I never have been one to take every bit of the choke and throttle mechanism off always afraid that I'd have some spring break or something but up until now I've had zero problems afterwards...til now. So rebuilt the original carburetor new float , polished the power piston the bores of the accelerator pump and the power piston. now I did not take the APT out cuz I didn't have the tool, nor an easy way to make on. Oh, one thing I did do on either carb, I did not stake the ball the check ball , but then I've never done that on any Quadrajet. Throttle shaft bushings seemed pretty tight (I know for a fact looking back on a 1971 Cadillac I had they were, still got 11 MPH and very good performance from a worn out carb)
    So, I put the lower mileage carb on (guessing car has 40+ K on it) and the same exact problems! secondaries don't open I can manually force them to open (and before putting the carb on, I saw the primaries and secondaries opened just fine. And I have that leaking/seeping issue at the top again around the air horn gasket maybe even slightly around the accelerator pump car. started okay no secondaries again must be something I'm missing .
    I know I'm much more familiar with carburetors from say 68 to 71 in that was most of the cars we had with quadrajets we put several hundred thousand miles on those cars for the years and didn't have weeping fuel at the top didn't ever have trouble with the secondaries so what the hell am I doing wrong now? (did just check something I stupidly forgot to, I was going between Doug Roe's book and Cliffs, the shop manual shows the 455 having 15/32 as the level, saw one of the main q-jet folks youtube say he puts most of them at 9/32, and I know the original float was set right around 15/32 number) If I had the 500 right now I would just send it off,but until I sell my 77 Regal I'm stuck with what I have.
    I rebuilt the hated (By me) 2GC on my 1977 Regal a few months ago, and gee, didn't screw that one up somehow. It's faster and gets better mileage to boot. But the Q-Jet muse has left me, I was apparently better at rebuilding them 30-35 years ago.
    Not sure it will help, but some pics.(taken at night , with a flash)
    thanks for any suggestions.
    EDIT: I forgot to mention I tried on the earlier carb blocking the vaccuum port to the rear pull off, still no difference. I tried adjusting the screw on the primary 1 too, with no changes. I even saw on Cliff's forum someone years ago wondering if fast idle cam might be "dry" tried oiling it, no change there either.
    20211107_175342.jpg 20211107_175335.jpg 20211107_175328.jpg 20211107_175358.jpg
     
    Last edited: Nov 9, 2021
  8. TORQUED455

    TORQUED455 Well-Known Member

    Does the choke blade open all of the way when the engine is hot?

    With the engine off, can you manually open the choke blade all the way and then open the throttle all the way? Do the secondaries open?

    With the engine off, have a helper put the pedal to the floor. Take the throttle linkage and try to open it further by hand to check the throttle cable.
     
    berigan likes this.
  9. berigan

    berigan Well-Known Member

    Bob, so very glad you noticed the choke blade/plate not being open completely! I thought Since it was dark when I took the pics, that the engine had merely cooled down a bit, and that's why it wasn't open all the way (I was so focused looking for some external linkage issue, or perhaps a vacuum issue) so, once my back was good enough to work on the car again, I started it up, let it warm up, and sure enough, the blade could be pushed fully open, but went back to partially closed. So, I loosened the choke screws , moved it way past where it would seem to need to be, and you could see the linkage relax, and the blade straight up! I could tell the secondaries did move more freely on the airhorn, and when I forced the throttle wide open, they tried to open a bit.
    So, full of hope, I said a little prayer, drove the car around the block and....Ahhh, there's that roar we all know and love :D
    I remembered that since the "old" carb had the nicer outer choke (the black plastic wasn't broken in the center) I decided to put in on the carb I rebuilt 4 + years ago, and the other choke on this carb, that came on the car. Well, even though it seemed like everything was set just as before, somehow, someway I F'ed something up, I guess on both chokes :( (had more divorced chokes, instead of these fancy modern ones in the past)
    Anyways, I can breathe a bit better now, I am an idiot, but not a COMPLETE idiot! And can once again feel I can actually rebuild a q-jet and not make things worse than before. I do still have that fuel seeping at the top, not as bad as the other day, but the Air horn gasket is slightly damp. Could the 9/32 float setting have any bearing on this? I was pretty sure it wasn't leaking before (I can really smell a fuel leak, most of the time) but it was a super filthy carb before I rebuilt it.. Seems I have it pretty tight, don't know if I dare turn it another 1/4 turn, or not. Don't want to warp it....if it wasn't already a bit warped.
    thanks again Bob!
     

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    FLGS400 likes this.
  10. TORQUED455

    TORQUED455 Well-Known Member

    I’m glad you got your secondaries back. Those hot-air chokes needed a lot of things to be “right” for them to work properly, and on a 45 year old car, keeping those things “right” is a never-ending chore. You can convert to an electric choke. And maybe experiment with a different float setting.
     
    berigan likes this.
  11. Cliff R

    Cliff R Well-Known Member

    I would suggest converting it to electric choke unless you are going to put a filter on the hot air supply tube to the intake. That is a vacuum supply and drawing dirty air into the engine. It will knock the rings out of it pretty quickly so either route it so it draws in filtered air or just upgrade to an electric choke and block the vacuum supply to the housing and be done with it.

    Many later carburetors will show a pretty "low" float setting in posted literature for them. They used pretty high pressure fuel pumps in the later smog years and return set-ups back to the tank to help keep the fuel cooler. If you are using a high pressure pump or have blocked the return you may need to use a lower float setting.

    Fuel pressure has a DIRECT impact on fuel level in the bowl. 9/32" on that carb works fine provided you don't have a high pressure pump. I run 7.5 PSI on my 1977 Q-jet and have for at least 30 years. I've won the Pontiac Tri Power Nat's at Norwalk 5 times, logged over 100,000 street miles and several thousand dragstrip runs and it's never faltered once, or shown any signs of the fuel level being too high in the bowl.

    Even with that said if you have an OEM fuel pump you will need to use the stock float setting to keep the fuel level in check. I had a customer recently rebuild his late 1970's Olds 403 carb and set the float to 1/4" and it didn't work well at all. He contacted me for help and I had him rig up a set-up to install a fuel pressure gauge. He said it was showing 10-12 PSI at the nose of the carb. He lowered the float to 15/32" and everything was fine. His car was a 14,000 mile survivor and still using the stock OEM fuel pump.

    Keep in mind when reading this that most fuel pumps have been changed out and very few these days will be making the same high pressure that some of the OEM pumps made......FWIW......
     
  12. berigan

    berigan Well-Known Member

    Cliff, very interesting, I never knew, nor would have thought of high fuel pump pressure! I bought this car online, and many mysteries abound. Tires were from the 90s, plates were from 96, but a battery from 2016. Last oil sticker on the door from 2013 said 35,000 (one from 95 said 23,000) so, what does the odometer say? 14,000! Figure that one out! Anyway, looked at the fuel pump and looks like blue paint on it, so guessing original?
    Oh, if I were put a vacuum cap on the port on the carb that goes to the secondary pull off, do I still leave the pull off and linkage on I assume?
     

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  13. TORQUED455

    TORQUED455 Well-Known Member

    If you have a correct and operating secondary choke pull-off now, leave it alone! That little air bleed won’t bother anything and with all due respect to Cliff, it’s not there in case the primary one fails. If you want to test it, pull the boot back and cover the little hole.
     
  14. Cliff R

    Cliff R Well-Known Member

    The secondary pull-off has NOTHING to do with any of the issues you've mentioned on this thread.

    Unless you missed it the fresh air supply to the choke needs to have FILTERED air or it will ruin your engine. It 's not connected to anything in they pics above which is not a good scenario.....FWIW........Cliff
     
  15. TORQUED455

    TORQUED455 Well-Known Member

    I agree with both of these. However, secondary pull-off was not engineered and installed for redundancy. The little bleed hole in it doesn’t bother anything. However, having the fresh-air supply to the hot air choke open to unfiltered air is a no-no. An electric choke conversion would solve 2 problems in this case.
     
  16. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    The secondary pull off has a delayed action due to the air bleed, and AFAIK, is for refined choke operation for better emissions.

    72QJPulloff.JPG
     
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  17. TORQUED455

    TORQUED455 Well-Known Member

    Larry, do you have a picture of the fresh-air tube to the air filter housing for the hot air choke on a BBB or SBB? I can’t for the life of me remember how Buick did this. Since Olds engines also used hot air chokes, and those engines were around a lot longer than Buicks, I remember how Olds did it but don’t recall if Buick was the same.
     
  18. berigan

    berigan Well-Known Member

    I perhaps wasn't clear about this, since you had said
    I was just thinking, why not bypass it and cap it's vacuum source, But, I'm hearing different opinions on this...so....I'm as clear as mud on this topic ;)
    Ok, folks say, it's easy peasy to go to an electric choke, but, I've never added an electric fan, choke, nothing....I wonder if a post is pinned on how to do that? Guess I'll look.


    I do still have the the fresh air supply to the choke going into the air cleaner (pre rebuild pic) upload_2021-12-4_15-46-14.png
     
    Last edited: Dec 4, 2021
  19. berigan

    berigan Well-Known Member

    I know this isn't exactly what you were asking for, but since I have this laying about (never swapped a q-jet on my 77 Regal), thought I'd take a pic
     

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  20. TORQUED455

    TORQUED455 Well-Known Member

    Conrad, I’m wondering how Buick got filtered air to the pipe. Olds used another metal pipe that slipped into the inlet of the choke tube and the other end went to the back of the carb. The carb passageway it attached to went up and was open to filtered air.
     

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