I was wondering if any one knows where the vacuum secondary tube attaches to the carb at?

I have got a 625 Carter bolted to a weiand intake with no additional vacuum lines and I dont think my secondaries are operating.

there is no "vacuum tube" it work's like a mechanical on the throtel plate area, the 2 big flaper's in the secondary bore's are the part's that open the fuel flow. they are pulled down by air flow and let fuel flow in the secondary circit. they use a counter weight to keep them closed, the air flow has to overcome the weight of this to open them.

the only way i know to test them is to plug the fuel disgarged tube's with rubber cap's and go do a run, time it, then do one unpluged time it too. if you see a faster time un-plugrded thaey are working right.

hope this help's ya out.

What makes you think that they are not opening? You shouldn't be able to "feel" then open. Many people go for that "kick in " feeling, but when you feel them come in, they are coming in to fast and what you really feel in the slight lean bog before the fuel catches up.

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www.grapeaperacing.com (http://www.grapeaperacing.com)

grape ape,

on a properly adjusted vacuum secondary carb you will not feel them "kick in" if you do then you are geting a bog from them opening too soon or beeing too rich. they do not work exactly like a double pumper.

this info is from holley, and edelbrock and carter. it is a fact. IMHO a vacuum secondary carb is better 99% of the time. david vizard and other's have had dyno shoot out's and the vacuum seconday carb did as well if not better then a double pumper.

these test's where done on motor's that had a street type build most roder's use. they where in the 350HP to 450HP at crank area. most where 350's but i have seen test using 327's and 400's. all ended up basicaly the same, the diferances where in the 5 to 10 HP area and in a street rod that is not gona matter realy.

double pumper's are best with a manual tanny, vacuum secondary's with a auto. but i have seen double pumper's work great with an auto and vacuum secondary's work as well with a manual.

i have a edelbrock 750 and road demon for my motor. i prefer the demon. the 750 has more top end but is lazy on the bottom end. the demon is more balanced all around and i get better econamy with it.

allso if you can rev the motor in park or neutral and get the secondary's to crak open it mean's nothing. they open depending on the load the motor is under, not the position of the primary throtel plate's.

oh and a vacuum seconday carb sizes it self to the motor, there by not giveing it too much fuel and air as easey as a double pumper can. i have seen a 650CFM vacuum secondary carb work better then a 650 double pumper on many motor's. vacum secondary carb's are also easyer too tune and dial in and give you less disapointment over all on street car. now a race car a double pumper is best, as you are at WOT 99% of the time.