Sorry, I thought earlier you said you had 14 In/Hg, but that was your Neutral Idle.
So, Yes, if you have 7 In/Hg at
"In-Gear Idle, 1/2 that would indicate a 3.5 or Holley P/N: 125-35 Power Valve.
Here is the Exact Quote from the Holley Website:
Quote:
Each Holley power valve is stamped with a number to indicate the vacuum opening point. For example, the number “65” indicates that the power valve will open when the engine vacuum drops to 6.5" or below. An accurate vacuum gauge, such as Holley P/N
26-501, should be used when determining the correct power valve to use.
A competition or race engine which has a long duration high overlap camshaft will have low manifold vacuum at idle speeds. If the vehicle has a manual transmission, take the vacuum reading with the engine thoroughly warmed up and at idle. If the vehicle is equipped with an automatic transmission, take the vacuum reading with the engine thoroughly warmed up and idling in gear. In either case, the power valve selected should be 1/2 the intake manifold vacuum reading taken.
EXAMPLE: 13” Hg vacuum reading divided by 2 = 6.5 power valve. If your reading divided by 2 lands on an even number you should select the next lowest power valve. EXAMPLE:
8” Hg vacuum reading divided by 2 = 4 power valve.
Since there is no #4 power valve you should use a 3.5.
