April 2010 Performance Q&A

Tom Truty Jan 27, 2010 0 Comment(s)

A: Those pesky secondary diaphragms can be a real pain to reinstall. Are you replacing the original diaphragm with a new one? With the age of your carburetor, it's virtually impossible to reinstall the original one. They shrink over time and it's tough even for a pro to get them back into place correctly. We've got a few tips for you to make the job easier.

First of all, go to Holley's website and download the Installation, Tuning, and Adjustment manual for the 0-3310-S carburetor. We're sure your carb is a different number, but the tuning and adjustment of the vacuum secondary diaphragm is the same. This instruction manual has a section titled Vacuum Operated Secondary Tuning. This has the instructions, photos, and tips on disassembling and reassembling the secondary diaphragm. It has a photo where the small check ball goes. There's even a nice tip on how to keep the secondary diaphragm in the proper shape for assembly.

A couple of tricks we've learned over the years is to use a bench vise to help in assembly. To put together the diaphragm assembly you really need three hands. Slide the new diaphragm into the base of the secondary housing. Using the vise, clamp the shaft of the diaphragm at the proper height to keep the diaphragm at the correct shape to match the base. Then, when installing the diaphragm cover, use a little white grease on the screws to prevent them from grabbing the rubber diaphragm and damaging it. If you don't use a little grease, the screws grab the diaphragm, twisting it out of shape and sometimes tearing the rubber.

Between the instructions online and a few simple tips, you should have your carb together in minutes. When installing your fresh rebuild, start with float settings and then get the idle fuel screws close. Set your idle speed and then do your final tune on the idle fuel screws. Doing these steps in this order will give you many years of great service from your Holley carb.

Source: holley.com

Quest For A Greater Understanding
Q: Hello! I have been a longtime reader of this wonderful magazine, but I suffer from a lack of real knowledge and comprehension when it comes to the finer details of how to design street or race engines. I have dozens of books and even some videos-and have read them all- but they seem to lack that next level I seek. Do you know of any books that can help me, aside from SA books? Or even better, some videos other than the Power Building videos? Any help or a point in the right direction would be much appreciated.
Thank you!

Ben C.
Bloomington, IL

A: Finding truly accurate data can be really tough. The Internet can be great, but you have to be very careful who you listen to. Anyone with a keyboard can present a very good line of info that could be a bunch of hogwash. We can think of a couple of books you need. Reher-Morrison racing engines released its Upper and Lower Engine Assembly books about eight years ago. These hold the secrets that only professional engine builders knew and used. They are both very informative and down to earth with their explanations and theories. Well, Reher-Morrison has just improved these books by taking more than a year revising and consolidating them into its new release, Championship Engine Assembly. The book is huge, containing 392 pages of information and over 600 detailed photos and graphics that show you the right way. Several colleges recently selected to feature it in their race engine technology programs, yet you'll find it easy to read, with simple terminology in carefully organized steps. Check with Reher-Morrison and pick up a copy of the book. You won't be disappointed.

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