Holley Help Needed

Don't get ahead of yourself with changing things before you see how they work.

A 3310 Holley 750 vacuum seconday carb will come with 72 primary jets and a secondary plate equal to either 75 or 76 jets. If you want to start experimenting with jets, you'll need to get a secondary metering block so jet changes can be made just like on the primary side. (The secondary side doesn't have a power valve and one shouldn't be added.) Holley does make a kit specifically for this that includes gaskets, longer bowl screws, etc.

As for the vacuum secondaries, it would be best to start out with the stock or heavier spring and concentrate on getting the idle and part throttle operation right. You may also need to play with the accellerator pump cams and squirters.

Once you get the feel of that, you can start experimenting with lighter springs while trying to keep the secondaries from opening too soon.

I'd suggest getting some soft cover books on Holley carbs. There is one by HP Books, authored by Mike Urich and Bill Fischer that's been revised over the years. It has some good explainations on how the variety of systems within a Holley carb work and what you can do to tailor them to your application. I've heard there are a couple of others that are good to learn from also.