Im just starting to punch my car here and there. I cant remember if i had mechanical or vacume seconarys on my old 69 chevelle, but i do remember when i punched it all hell broke loose and you got a kick in your back

It was the secondarys opening, everybody knows what that feels like.

But i do have vacunme secondarys on this motor in my camaro, and i dont feel that punch. It revs up there, but its too seamless, like there almost not opening.

It gets that real deep tone, and like i said gets up there, but where the heck is the punch? The guy that built my motor just set my carb, he said you need vacume to open them and ive got vacunme, or so he says.

Could it be that my return spring is holding them back or my lokar throttle cable is preventing it??? Maybe not adjusted right? I never really checked it for pulling the throttle open all the way.

I really want to see what this thing can do. Whats going on??

As usual , thanks.

Not sure what carb you're using, but take a look at this link, in particular page 11. Holley says you won't feel a "kick" if the secondaries are working right.

http://www.holley.com/data/Products/Technical/199R10219-3.pdf

to actually see if your vacum secondaries are kicking in get a very small tie wrap and put it on the vacum pod linkage arm just below the bottom of the vacum can . now go out and do a few spirited test runs opening the throttle all the way . next open the hood and check to see if there is now clearance between the tie wrap and vacum can .this will actually show you that the secondaries are opening up by doing this test .

other things that might be causing you not to feel the secondaries opening up is the spring in the vacum diaphram .they make different springs so you can tailor your secondary opening rate


the different springs are :

white
yellow
red
purple
green
pink
orange
plain - unpainted
brown
black

the best spring for your application is by trial and error .settle for the firmest spring that gives the quickest acceleration . a correct spring choice will make sure that the primary barrels are near to reaching their maximum airflow capability before the secondaries start to open .

if the carb is sized correctly to the engine , the softer springs ( white ,yellow, red ,pink or green ) will usuallly work alot better than the harder springs ( brown and black) . consider the stiffer springs brown and black more suitable for larger displacement engines

one other thing to remember is to these springs , the first is that the softer the spring the faster the diaphram will open allowing faster secondary opening . the other is is the rate at which they allow the secondary throttle shaft to open up once the vacum threshold has been reached . now going to soft of a spring and you'll get a very noticeable bog once they open and to stiff of a spring and they won't open until very high rpm or not at all depending on vacum the motor can put out


i hope this helps you !!!!!!!:) :)

Just a little clarification. The vacuum that controls the secondary opening on a Holley carb is not the same as manifold vacuum at idle, which is a common misconception. As air is drawn through the primary venturis it passes over a siphon, which causes a vacuum effect, and depending on the setup of the carb, allows the secondaries to open up. This allows the carb to meter fuel as needed based on the air flow that is entering and is why vacuum secondary carbs are better suited for street applications where wot is rarely seen.

Your Chevelle might have used a Q-jet, which has very small primaries for economy and large secondaries (3x the size of the primaries) for acceleration. Tuned right, the Q-jet can give the feeling you describe.