Holley powervalve rating

[dutchrunner]

Still fine-tuning the 6-pack on the 528 RB.

Just wondering what happens if the powervalve rating in centre carb is to low?

Have 3,5 inside now and 7 inch vacuum (hot@1000rpm).
Will change to 2,5 to clean-up the idle and low-load situation.

Any-body ? Pro-max guy ?

Greetings and Thanks Bigfoot

 

[moparchris]

Still fine-tuning the 6-pack on the 528 RB.

Just wondering what happens if the powervalve rating in centre carb is to low?

Have 3,5 inside now and 7 inch vacuum (hot@1000rpm).
Will change to 2,5 to clean-up the idle and low-load situation.

Any-body ? Pro-max guy ?

Greetings and Thanks Bigfoot

A 3.5 power valve opens at 3.5 inches of vacuum. Since you have 7 it is closed for sure at idle. You have the right power valve in it.

 

[69hemibeep]

Still fine-tuning the 6-pack on the 528 RB.

Just wondering what happens if the powervalve rating in centre carb is to low?

Have 3,5 inside now and 7 inch vacuum (hot@1000rpm).
Will change to 2,5 to clean-up the idle and low-load situation.

Any-body ? Pro-max guy ?

Greetings and Thanks Bigfoot

A 3.5 power valve opens at 3.5 inches of vacuum. Since you have 7 it is closed for sure at idle. You have the right power valve in it.

I agree, unless its bad, then it will load up

 

[dutchrunner]

Yeh '.

Thats what I tought , but looking in Holley book it states that engines with can >285 duration will have lower intake vacuum during lightloads than it has during idle.

Also the STR manifold with VERY large plemium will not help the idle vacuum signal.

Due to this I am thinking of putting an 2,5 inside.
To be sure I have to extend the vacuum hose form intake to outside enginebay and connetc the gauge and wach is during lightload conditions.

Main question is what happends if powervalve rating is to low?

 

[6R9Runner]

Main question is what happends if powervalve rating is to low?

Then the power valve will not open until the engine is at an even higher load condition, i.e. higher rpm. The power valve enrichment will be delayed further/ will have less effect.