Low on power?

[patrickt]

Originally Posted by cobragene

Maybe I should look into the pump cam or it’s timing? I know one thing at a time.

No, let's just get the secondaries to open fully. If you have enough air rushing by the signal tap hole, and the linkage and vacuum diaphragm are both working properly, then the secondaries should open completely with a soft spring. It really is as simple as that. Maybe there's a little chunk of gas goo in the signal tap hole. Make sure it's good and clean when you have the diaphragm off.

[jhv48]

You can adjust and readjust the vacuum secondary carb over and over but if you want that immediate power, you’ll have to ditch the carb and put on a double pumper.
Just buy/borrow one and stick it on. You won’t regret it. Even on Holley’s web site they recommend mechanical secondary carbs instead of vacuum secondary carbs for our cars due to their light weight.
I’ve done it twice on two different cobras. Both came with vacuum secondary carbs. One a Holley street avenger the other an Edelbrock AVS. Fiddled with both until I decided to bite the bullet and buy a double pumper. Woke those engines right up and now I can break the tires loose in fourth gear if I’m not careful. And that’s with sticky 180 treadwear 315’s.
Just do it.

[patrickt]

Originally Posted by jhv48

You can adjust and readjust the vacuum secondary carb over and over but...

That's a fair comment. If we can't make him happy with our $38 toy, then that's his next step.

[patrickt]

Cobragene, I'm still suspicious that there is something that is just not working right on your vac secondaries. I'd like to see if you can "force" them open with a tremendous amount of venturi vacuum. So, get a wash cloth out of the bathroom and take your car out to a reasonably deserted straight away. Then remove your air cleaner and drape the wash cloth across the driver's side half of the primary side, so that the carb is only breathing through the passenger side of the primary. Your car is now essentially a one-barrel carburetor. Set your zip tie so you can measure secondary opening. Then put the air cleaner back on so it holds the wash cloth in place and run it down the highway at full throttle, stop, remove the wash cloth and examine the zip tie. Unless something is broken that is virtually guaranteed to open the secondaries fully.