power valve check ?
- Thread starter merc40
- Start date
19Fordy
Well-known member
Found this info. on another site.
To check with the carb on the engine and the PV still in the carb just start the engine put your finger over the carb bowl vent and if the engine stalls right away the PV is blown. If it take 3-4 seconds for the engine to stall the PV is OK. To check with the carb on the engine and the PV still in the carb just start the engine put your finger over the carb bowl vent and if the engine stalls right away the PV is blown. if it take 3-4 seconds for the engine to stall the PV is OK
And this:
From Holley:
THE TRUTH ABOUT POWER
VALVES USED WITH HOLLEY
CARBURETORS
There still seems to be a lot of misconception about
Holley carburetors blowing power valves. Nothing
could be further from the truth. Holley performance
carburetors built since 1992 have utilized a power
valve check system that effectively eliminated this
infrequent problem. Consisting of a spring, brass
seat and check ball, the check ball system is 100%
effective protecting the power valve diaphragm
from damage due to engine backfire.
The power valve check ball is designed to be
normally open but quickly seals to close off the
internal vacuum passage when a backfire occurs.
Once closed, the check valve interrupts the pressure
wave generated by the backfire, thus protecting the
power valve diaphragm. There is no way that the
power valve’s diaphragm can rupture due to an
engine backfire!
If you have a carburetor older than 1992 (or you have experienced
an extreme backfire) and expect a blown power valve,
use this simple test. TEST: At idle turn your idle mixture screws
(found on the side of the metering block) all the way in. If your
engine dies the power valve is not blown. You can see this in the last sentence of this video. http://www.youtube.com/watch?v=6vKlAnKdcB4
THE TRUTH ABOUT POWER
VALVES USED WITH HOLLEY
CARBURETORS
To check with the carb on the engine and the PV still in the carb just start the engine put your finger over the carb bowl vent and if the engine stalls right away the PV is blown. If it take 3-4 seconds for the engine to stall the PV is OK. To check with the carb on the engine and the PV still in the carb just start the engine put your finger over the carb bowl vent and if the engine stalls right away the PV is blown. if it take 3-4 seconds for the engine to stall the PV is OK
And this:
From Holley:
THE TRUTH ABOUT POWER
VALVES USED WITH HOLLEY
CARBURETORS
There still seems to be a lot of misconception about
Holley carburetors blowing power valves. Nothing
could be further from the truth. Holley performance
carburetors built since 1992 have utilized a power
valve check system that effectively eliminated this
infrequent problem. Consisting of a spring, brass
seat and check ball, the check ball system is 100%
effective protecting the power valve diaphragm
from damage due to engine backfire.
The power valve check ball is designed to be
normally open but quickly seals to close off the
internal vacuum passage when a backfire occurs.
Once closed, the check valve interrupts the pressure
wave generated by the backfire, thus protecting the
power valve diaphragm. There is no way that the
power valve’s diaphragm can rupture due to an
engine backfire!
If you have a carburetor older than 1992 (or you have experienced
an extreme backfire) and expect a blown power valve,
use this simple test. TEST: At idle turn your idle mixture screws
(found on the side of the metering block) all the way in. If your
engine dies the power valve is not blown. You can see this in the last sentence of this video. http://www.youtube.com/watch?v=6vKlAnKdcB4
THE TRUTH ABOUT POWER
VALVES USED WITH HOLLEY
CARBURETORS
Last edited: