Now that I have the engine work completed, I want to dial in the 650cfm Holley I have.  I measured the vac @ idle in drive, and I get 17" Hg.  The rule of thumb I recall for selecting the value for the Power Valve was 2" Hg less than the vac reading @ idle, which would indicate a 15" Hg PV.  Holley only supplies PVs up to 10.5" Hg.  I'm anticipating a lean stumble under acceleration, due to the PV not opening until the vac drops to 10.5"Hg.   Any suggestions? 

Thanks

 

BB NJ Ken

Sorry , no, it is 2" vac below the "lowest" constant vac you see driving the car ,i suppose.So therefore you need to line upp a vac meter in the car and go driving and measure vac at constant speeds .

A Holley factory set is a power valve 65 or 85 , i'm trying them both .

I tought a 600 and 650 have a 65 , from 700 and up there's a 85.

Good luck !

PS try it first and if problems you can always read our thread " what did i wrong".....

 

 

[QUOTE=windrider1200]

Now that I have the engine work completed, I want to dial in the 650cfm Holley I have.  I measured the vac @ idle in drive, and I get 17" Hg.  The rule of thumb I recall for selecting the value for the Power Valve was 2" Hg less than the vac reading @ idle, which would indicate a 15" Hg PV.  Holley only supplies PVs up to 10.5" Hg.  I'm anticipating a lean stumble under acceleration, due to the PV not opening until the vac drops to 10.5"Hg.   Any suggestions? 

Thanks

BB NJ Ken

[/QUOTE]

Take it off your Vette and back to where you bought it....get your money back.  If ya wanna race carb, check out the Demon (sp?) at Summit or Jegs.  Just my 2 cents.

The Demon is great on a dragstrip, but TERRIBLE on the street.

The engine mods were selected to provide a low to mid range boast in torque, so I thought the 650 Holley would be a decent selection for the street / cruise / take the wife on a Sunday afternoon ride type scenes.  I'll try a few more info sources, and unless it indicates otherwise, I 'll try a 10.5" PV, and go from there.  Thanks to all for sharing thier thoughts.

http://community-2.webtv.net/MATTGRU/pv/

This might give some useful info

http://www.bob2000.com/carb.htm

this one might be of use also