Classic/Antique Car Repair: 68 gto, edelbrock performer manifold, vacuum hoses

Question
Dick
I am kinda new to the restoration of older cars so this might seem first hand to one that has been in the hobby for a long time.  I have a 68 gto with a 400, edelbrock performer manifold and a edelbrock 600 quad & electronic ignition.  I seem to have a vacuum leak somewhere that I cannot find.  I have sprayed wd40 around the base of the carb, the vacuum ports, the brake booster and I do not get a reduction or increase in the rpm.  The rpm is about 800 when attempting this.  I only have two vacuum hoses, one to the headlight doors and one to the dist.  I have yet to retorque the manifold just to see if it makes any difference.  I can screw the gas and the air mixture completely in and it will continue to run.  The carb is new, I have replaced it once thinking that there was something wrong with it but the second one does the same thing.  So am I doing something wrong or is there something that I have overlooked?  The performance has improved since I have replaced the Holley with the
edelbrock and replaced the dist. with the electronic but it still doesn't have the power that I feel the 400 should have.  It also doesn't have any off the line acceleration like it should, I have removed the dif. housing and counted the teeth, tho I can't seem to remember what they are at this time, an auto buff that I have spoken to about this recommends a 326.
So any help you might be able to give would be greatly appreciated.   Thanks kevin  

Answer
It sounds like you have a massive vacuum leak.  You should disconnect and plug the connections to the brake booster, the AC control, the charcoal cannister, and headlight doors, and anything else that is vacuum operated on the car.  Just find all the connections for hoses to the intake manifold, including the PCV valve and block off those connections AT THE INTAKE MANIFOLD!.  The line to the distributor is ported vacuum, so it doesn't affect the idle (there should be no vacuum in that line at idle - if there is you have it hooked to the wrong port.)

Are you sure you have a cap over all the unused vacuum ports?

Once you have EVERYTHING capped off, then take a 3 foot length of garden hose and put one end to your ear, the other end you move around the engine listening for any sound of air rushing.   If you can't find it that way, take a propane torch, don't light it, but turn it on and put it all around the intake manifold and base of the carburetor.  When you find the leak, the engine will rev up.

If you want to prove that you have a vacuum leak, start the engine and then take a piece of cardboard and slowly slide it across the top of the front barrels of the carburetor, so as to block the flow of air into the top of the carburetor.  If at ANY point of doing this, the engine speeds up, you know you are running with too lean a mixture, and the only reason for that is that you have a vacuum leak.  Keep looking and listening, you'll find it!  (My money is on the brake booster or the PCV valve!)

Good Luck,

Dick