k i took it in the shop to have them look her over you know .. its a vaccuum secondary 750 holley. there is a vaccum line going from the carb to the distributor. and there is one going to the power brakes. and there is one more hole left but they capped it off and the other vaccuum lines are open. im not the carborator GOD so im asking you guys i dont think the car has enough GO to it cause i thought you could hear secondaries when they open. can somebody give me some tips ?

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350 bored 30 over ..882 casting heads ..comp cam..hooker headers.. 700r4 corvette servo .. 3.73 and SLP posi no hood on the car , holley 750 CFM, performer RPM intake.. and umm couple other things here and there

 

I ran a 750 vacuum for a long time. You probably won't hear them open. They're controlled by manifold vacuum, and are governed by spring pressure. Depending on which spring you have installed, they won't open until a certain rpm. The best way I've found to check if they're working is to block the secondary linkage so they won't open, and take a test drive. If you lose a bit of power, then the secondaries were opening properly. Get a set of assorted secondary springs, and a quick change kit. You can change opening rpm with different springs. The quick change kit will make it much easier to change springs.

[This message has been edited by Formula-91 (edited June 03, 2001).]

 

I'm running a 600CFM vac' sec' Holley on my 305. Had the same problem... found the small ball bearing inside the secondary diaphram housing was stuck in the hole! This is used to prevent the secondary opening to quickly, as far as I can tell. Anyway, I removed it all together and tested it using a loosley fitting, trimmed, cable-tie on the secondary shaft(Tells you if the thing moves and how far). Works great. Also found better operation by installing a weaker spring. Now I know a lot of people out there cringe at the thought of modifying carby's like this but, quite frankly, that ball bearing just seemed to hinder the operation of the thing. Anyone else had this?

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1986 Pontiac TransAm - LG4 - Vin H - 5 Speed Manual - Righthand Drive - Performer Intake - Holley 4160 600 - No Cat - no emmission equip.

 

With the right combination, you don't need that ball. The vacuum secondaries should come in gradually. Adjust them my installing the next weaker spring until you get a bog--then move one spring back(the best way is on the track but that might not be possible)



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