just havin a look at my carb (looking down into it), and decided to move the diaphram which controlls the secondaries, the secondary throttle plate only moves about 1mm when i fully push the diaphram and doesnt go further. i mean is this right surely its suppose to open up a lot more?

get some photos mate, its been a long time since i have worked on a std magna carbi

heh no probs, give me some time. from what i see they are mechanicaly activated secondaries but then i done see the purpose of the vacuum apart to "smooth" the transition when they open.

im guessing under WOT under load (ie driving the car) both primaries and secondaries throttle plates would be fully open.

yep. the secondary release control (the vacuum controlled diahpram) is there to aid torque and increase intake velocity at lower rpm, much like newer cars dual length runners and secondary butterflies in efi cars. if youdecrease the air velocity by opening the secondary too early then u get a pretty ****ty mixture of fuel because the secondary pretty much pours fuel in, it doesn't really try atomise it like the primary squirter does. so with low air velocity your secondarys can bog the car down and infact hinder performance if not sorted out properly.

still waiting pics

well lookin around and manualy playing with the secondary throttle plate it indeed moves etc. now the question.... (see attached drawing to get the idea). is that check ball (a tiny little metal ball) suppose to be in that line. from the magnas ive seen at the wreckers no. if i take it out and connect the line back and drive the car it is a LOT better. but when the cars idling it lopes from about 900rpm to 1200rpm because the constant vacuum on the diaphram up down up down up down....... i think the line to the base of the carb is for vacuum relief?

i connected the other end "vacuum soruce" to a open direct vacuum port on the manifold (i could feel the vacuum on my finger.... howerver the stock magna configuration is to run it to the vacuum thermal valve (which opens when the engine is at operating temp) (its located near the dizzy ull see it has about 3 or 4 vac connections to it. when i hook it to that its hard to say if i get vacuum at all i put my finger on various holes and nothing (yes i have 1 line commin from the manifold to it - after all it needs to "switch" something - it doesnt provide the vacuum). but it feels like a weaker vacuum that cant be right.

oh the check ball shouldnt be there i mean it goes in VERYYYYYYY tight. i think its there to block it off.

yes, the secondarys on the std magna carb are definately vacuum operated. cant believe u thought they were mechanical jason, thats y we all made such a big fuss wen we got the falcon carb on and it had mechanical secondaries.