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Old 05-27-2018, 09:45 PM
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Tom Vaught Tom Vaught is offline
Boost Engineer
 
Join Date: Dec 2001
Location: The United States of America
Posts: 31,302
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Yes that is correct.
Stock, as you know is 2 Power Valve Channel Restrictions typically .059" on a 850 cfm 4781 Holley carb.

Low boost PVCRs can be increased to about .084" for each one.
More boost then you drill (and add 2 more PVCRs at .059" and based on your boost and AFR numbers drill those out to the size needed.
Again stop around .084" for each one.

If you are like Charlie, Lots of Boost, then you go with SIX PVCRs and go thru the same enlargement process along with bigger jettings too.

Hope that helps. AFR/Lamda Gage is your friend, along with a SHOTGUN RIDER actually reading and documenting the AFR/Lamda numbers on a clipboard. Fast car with lots of boost, hard to do it all yourself safely.

Tom V.
ps Find a very quiet road that you can use for your tuning without irritating the locals.

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