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#1 |
Registered User
Join Date: Jul 2007
Location: Fall River California
Posts: 2,026
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Just installed new Quadrajet, secondaries not opening
Got a summit Quadrajet installed on my 350, all went fine, engine started right up and runs smooth, revs fast and idles nicely but I can't get the secondaries to open. The valves open about 1/4 to 1/3rd and the upper butterflies only start to open. The spring tension seems stronger on the new carb than my old one. I bought this carb from a guy who bought it but never used it. The choke is wide open so it's not locking the secondaries out. Any ideas?
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#2 | |
Registered User
Join Date: Jul 2007
Location: Fall River California
Posts: 2,026
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#3 |
Registered User
Join Date: Jul 2007
Location: Fall River California
Posts: 2,026
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Re: Just installed new Quadrajet, secondaries not opening
I just noticed the teams kickdown cable seems to be my problem, it won't allow the secondary linkage to travel far enough. The throttle cable and trans cable mounts although slightly different where the cables attach but they are in the same position as I set them side by side. My old linkage required a cotter pin to mount the trans cable, the new one required I slide the cable to the round hole in the end of the slot in the end of the cable, thanks for any suggestions!
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#4 |
20' Daredevil (Ret)
![]() Join Date: May 2003
Location: Jefferson State
Posts: 13,644
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Re: Just installed new Quadrajet, secondaries not opening
My knowledge of carbs, including the Q-jet on my 350, is poor at best, so take this with a grain of salt. It's my understanding that the secondaries are vacuum operated and open on demand, so you're not likely to see them open in your driveway. Not much help, I know, but that's about all I have....
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- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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#5 | |
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Join Date: Jul 2007
Location: Fall River California
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Re: Just installed new Quadrajet, secondaries not opening
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#6 |
laying low
![]() Join Date: Mar 2001
Location: Searcy, Ark. USA
Posts: 13,267
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Re: Just installed new Quadrajet, secondaries not opening
So it has full movement with the trans cable disconnected?
Oh crap. You have overdrive don't you? As you well know that tv cable action has to be just right or trans damage is almost certain.
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Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross Last edited by Boog; 08-03-2015 at 06:26 PM. |
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#7 |
Registered User
Join Date: Jul 2007
Location: Fall River California
Posts: 2,026
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Re: Just installed new Quadrajet, secondaries not opening
Yes, the secondaries operate with the cable disconnected, the cable seems too short. I held the carbs side by side and the mounts for throttle and the TV cable seemed to be in the same position. The linkage looks slightly different but I'm thinking there must be a difference in its throw. Is the TV cable adjustable?
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#8 |
laying low
![]() Join Date: Mar 2001
Location: Searcy, Ark. USA
Posts: 13,267
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Re: Just installed new Quadrajet, secondaries not opening
Yes it is. There where it plugs into the bracket there should be a sort of round top. You press it down and cable housing should slide in or out of it. It's been a while since i messed with one of those. Anyway with the cable connected to the carb press in on that button and hold while you push the carb linkage to full open then release that button you were holding down. This will pull the housing out closer to where it needs to be. This should get the tv cable reasonably close.
This is assuming you have an OE type cable.
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Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross |
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#9 | |
Registered User
Join Date: Jul 2007
Location: Fall River California
Posts: 2,026
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#10 | |
laying low
![]() Join Date: Mar 2001
Location: Searcy, Ark. USA
Posts: 13,267
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Re: Just installed new Quadrajet, secondaries not opening
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The adjustment procedure I showed you above came straight from a service manual so it should be close. Happy motoring.
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Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross |
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#11 | |
Registered User
Join Date: Jul 2007
Location: Fall River California
Posts: 2,026
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#12 |
Registered User
Join Date: Apr 2011
Location: Klein Texas
Posts: 3,852
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Re: Just installed new Quadrajet, secondaries not opening
TV cables are adjustable BUT to control line pressure in your trans.
They used TH700 in carb applications so there should be enough travel. Again proper adjustment and geometry are needed to have proper trans pressure
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My Classics: '72 K20 Suburban + '65 Dodge Town Wagon '72 Corvette Roadster +'67 Corvette Roadster '73 Z-28 Camaro '63 Ford SWB Uni Pickup '50 Ford Coupe |
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#13 |
Registered User
![]() Join Date: Feb 2013
Location: Spring Hill, Florida
Posts: 465
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Re: Just installed new Quadrajet, secondaries not opening
If the trans cable is limiting the lower butterflies from opening then that is your problem. the other problem could be that the spring tension on the air valves/ upper butterflies is set to tight and not allowing the air valve to pop open at your engines full vacuum.
to set the spring tension there is a pair of screws on the choke side of the carb. on is a small flat head screw and the one underneath is an allen and locks the setting. a good starting setting is to loosen the tension until there is no tension on the air valve... or just enough to keep it closed. then tighten the tension one full turn and lock it down. drive the truck and punch the throttle at wide open and accelerate form say 30 mph if you get a bog when the secondaries open the spring is to loose. if you do not get a bog it could be to tight. loosen or tighten 1/4 turn of the tension spring. test drive again and adjust 1/8 turn to 1/16 turn past where the bog goes away and your secondary air valve should be set perfect. |
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#14 |
Registered User
Join Date: Apr 2011
Location: Klein Texas
Posts: 3,852
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Re: Just installed new Quadrajet, secondaries not opening
He did say "TV cable"
![]() TH350 doesn't have a TV cable
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My Classics: '72 K20 Suburban + '65 Dodge Town Wagon '72 Corvette Roadster +'67 Corvette Roadster '73 Z-28 Camaro '63 Ford SWB Uni Pickup '50 Ford Coupe |
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