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  #1  
Old 07-14-2008, 05:39 PM
Scremn Scremn is offline
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Location: Columbus,Ohio
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Default secondary power valve

I have purchased an 800 dp holley for my 72 Demon with a 340
4-speed in it.It has a secondary power valve in the metering plate.
Should I leave the power valve in the secondary metering plate or
plug the power valve?I know that on typical holleys with a single
power valve the secondary jets are 6-8 jet sizes larger than the
front.Will it be easier to properly tune this carb with or without the
sec power valve.The carb has 2 corner idle system.Your opinions are
appreciated.
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Old 07-14-2008, 08:16 PM
fox fox is offline
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Why not try it like it is?
Are the 4 jets near each other in size?
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Old 07-14-2008, 08:18 PM
turbododge turbododge is offline
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A lot of folks don't like the secondary power valve, but with a stick especially, I do. It will allow you to tune the secondaries for a smoother transition from the primaries, and also give you a big break on "feathered throttle" conditions, where the secondaries may still be open some, but there is vacuum in the intake. The 800 on a 340 is going to be pretty big, especially if it is a square bore, unless you are going to run some pretty high rpms. It will be tough to tune for good low end jump and hard to keep your foot out of it enough to prevent bog at low-mid rpms.
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Old 08-31-2008, 02:47 PM
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shelby340 shelby340 is offline
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turbododge...when you say "It will allow you to tune the secondaries for a smoother transition from the primaries" Can you elaborate further on that. Should the difference in front and rear jet sizes be less than one would have if a secondary powervalve was not in use?
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Old 08-31-2008, 06:48 PM
rusty duster rusty duster is offline
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put a plug in the sec. and get a notched float and jet extensions.Most likely you will need a bigger pump shot too.
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