<VV> 390 Holley Carb

Sethracer at aol.com Sethracer at aol.com
Tue Oct 11 11:25:04 EDT 2005

In a message dated 10/11/2005 8:17:31 AM Pacific Daylight Time,  
rsampson at swbell.net writes:


I need to lower the vacuum at which the  secondaries open .

Anyone know how to ?   I'd  like to try to increase my gas  mileage.....


The secondary action is controlled by vacuum overcoming the spring in the  
diaphram. Holley sells kits with various strength springs to "allow" the opening 
 of the secondary. I thinks a kit contains 5 or 6 different strengths - they 
are  color coded, as I recall.
Acccording to Holley:
The opening rate of a vacuum secondary system is controlled by the  diaphragm 
spring located in the vacuum secondary diaphragm housing. A “lighter”  
spring will allow the secondary throttle plates to open more quickly. A spring  
assortment kit, Holley P/N 20-13, is available to help you “tailor” the  
secondary opening rate to your application. A “quick change” kit, Holley P/N  20-59, 
is also available for fast and easy access to the spring. It consists of  a 
two-piece secondary diaphragm housing cover which, after it’s installed, can  
easily cut in half the time required to change the secondary spring.
Check _www.summitracing.com_ (http://www.summitracing.com)  for  easy 
pricing.   - Seth Emerson

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