typhoone Posted May 14, 2007 Share Posted May 14, 2007 i am trying to help out a friend of mine, he has a 327 crate engine with a holley 600 carb. he put in a bigger power valve becuase he wanted some more power, but now he wants to put it back to stock. there are 3 power valves sizes; 65, 45, & 35. does anyone know which one is the stock one???? Thanks in advance. -Typhoone Quote Link to comment Share on other sites More sharing options...
specialk Posted May 14, 2007 Share Posted May 14, 2007 power valve sizing is based upon how much vacuum the engine draws at idle. Do a google search for the replacement information. Quote Link to comment Share on other sites More sharing options...
icewtr Posted May 14, 2007 Share Posted May 14, 2007 Ok there are more than 3 sizes of power valves.. the way ya wanna chose the right one is get yourself a vacuum guage to hook on the carb and at idle in gear check the vacuum.. then get a powervalve about 3 in lbs lower than the vacuum ya show at idle in gear.. so if ya show 8in at idle then get a 5 the number on the powervalve is the point it opens due to vacuum... Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted May 15, 2007 Share Posted May 15, 2007 I've got two 600 holley here but I would bet they've both had different powervalves put in them. The above is good advice. Holley recommends getting a powervalve that is half of the vacuum at idle (sitting in gear with an auto and in neutral with a standard). 3lbs less might give you a little quicker response but I don't think it's a difference that you could feel without seeing a difference at a track. Quote Link to comment Share on other sites More sharing options...
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