Help! New Holley 750 vac sec issues

[Hemimad]

I recently decided to change the carb on the 70RR for a brand new 750. My old 750 was fine but ran a little rich but mainly grubby looking. It took about 30mins to swap over, however there is now a serious lack of power, it's as if the secondary is not opening, when hot it idles fast and in now runs on. I checked the timing and that was fine on the plus side the smell out the pipes is better, is there anything obvious that I might of missed that would cause all these issues simultaneously?

[TW71]

It sounds if the idle problem may be the blade/ butterflys over the transition slot (too high) if the idle screws are not working that is. Check the manifold vacuum etc. I take it that the timing is ok if it ran well before? I take it the fuel levels are set ok!

The secondry problem maybe the vac. secondry spring is a different colour to the old one i.e. stiffer, unless they are not working at all which would be very unusual.

[megla]

Are you trying to run the carb straight out of the box. the first thing that needs doing is to set the float levels at the correct height, and then check that the two shooters or accelerator pumps are squirting onto the primary throttle blades, these two functions are critical for proper power! With the fuel line under pressure look over and into carb , while opening the throttle you should see the shooters squirt in.

[ANTON]

You need to remove the carb and make sure the secondary throttle blades are set correctly. The adjuster screw can only be accessed with the carb off. If the secondary blades are open too far the normal idle screw will have no effect.
Check what secondary spring you have in the old carb. New cards normally come with a black spring. Also check what accelerator pump cam you had in the old carb as a new one comes with the orange cam.

[DaveB]

vac leak or linkage binding on manifold possibly