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vac secondaries

863 views 2 replies 3 participants last post by  jamesk 
#1 ·
A mate of mine thinks his secondaries on his 750 are not working properly.
What can we try/do to see if they are working or not?
 
#2 ·
He probably needs a weaker spring inside the vacuum diaphragm.
He'll need to buy a spring kit.

Take the spring out and drive it without it, and see what happens. It will very likely open to early and stumble so you can try different spring tensions and find the right one.

Rick.
 
#3 ·
I did this to test mine, its on the holley web site.
still uncertain if they are opening or not you can take a normal paperclip and clip it onto the secondary diaphram rod. You will then push it up against the bottom of the secondary diaphram housing, now you will need to go out and drive the vehicle. When you return you will be able to look at the position of the paperclip on the rod. If it is lower on the rod then you can tell the secondaries opened and how far they opened
 
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