I have a 91 350 engine with a Holley 750 carb. I finally got it out on the road and the secondaries won't open. My friend said they are vacuum secondaries if it helps. The car is still fast, but not the beast it use to be. How do i get them to open? Please help. Thanks

 

Are you sure they don't open. It's a gradual process that should be a smooth addition of power. They only open under load so revving the engine in P or N won't open them.

Make sure the throttle is opening all the way when the pedal is pushed to the floor.

Open the secondaries with the engine off to make sure they aren't stuck.


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82 camaro--original steering wheel, brake/gas pedals, seats--everything else modified
82camaro

 

What he said. How do you know the're not opening? IF you are sure they aren't, it'll only be one of 2 things. either they are stuck shut, or the vacuum passage is clogged. So, unstick it or spray it out with carb cleaner.

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"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
JSP Motorsports
ICON Motorsports

 

my friend took a look at it and he said there is like a little ball in there, is that supposed to be in the carb or not? i am pretty sure they are not opening or if they are not all the way, the car feels like it wants them to open. how do you adjust it though, i've never done this before. thanks again

 

Okay, here's a little Holley performance carb tuning 101. To get a carb with vacuum secondaries to open quicker look at the linkage to the secondaries. You will see that it has a slot in it that the linkage must make up prior to the secondaries opening. If you don't understand what I'm saying just go play with the secondaries awhile and watch the linkage. You'll see what I mean. Get a small screw and nut and place them along this slot and tighten it down. You can put it right up against the arm that slides along the slot or put it down further, experiment and see what works best. This effectively opens the secondaries quicker. If you think your secondaries are not opening this will force them open. If they are jammed you will know it when you test it after insalling the screw and nut. Hope you enjoy the quicker response.

 

Yes that little ball is supposed to be there,if youre secondarys arent stuck closed you have to much spring pressure on the secondary vacuum diaphram.You can order a kit through summit or whoever and there is several springs included in kit for tuning.

 

Also don't forget to check that your diaphram is not leaking .

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Big 454 72 Chevy Nova
383 86 Camaro Z28

 

THanks for your help. I'll see what i can find out. i miss the power!!!

 

On my setup, even w/ the lightest spring for the vac secondaries, they didn't open up fast enough for my liking, so I removed the check ball. According the documentation I had that is supposed to basically allow the secondaries to "flop" open as soon as they start to open at all, instead of gradually opening. My car seemed to like that still w/ the weakest spring... Try it if you still don't think they're opening quick enough once you start tweaking on them.

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Ray87Z
-Vortec headed 350.
86 IROC w/ a cammed 305 TPI.
Formerly Ray86IROC.
www.inter-scape.com/Ray

 

I had this problem with mine, there is a hose that leads to the vacuum secondaries diapham in the very fron tof the carb this holds them closed if you plug it and now try it. If this doesn't work are you able to push the secondaries open with your finger or are they like glued shut?

 

a hose? where?

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Big 454 72 Chevy Nova
383 86 Camaro Z28
10.5:1compression 186 casting Heads,234dur.488lift exh&int,Edelbrock performer intake, Holley750 vac.sec 400 crank,flat top pistons,edelbrock valve springs and lifters,tranny shift kit,kickdown kit and tranny oil cooler. Will install 3.73's later on and might go with a more aggresive cam.