Dummy Question of the day!
Fact:
Cam grinds will effect the amount of vacuum an engine produces with the throttle closed.
I'm running the 270-62h cams and am seeing 12-14 vac. at idle(850-900rpm)
Question:
What explanation is there for an engine that produces more vacuum with a slight tip of the throttle than what it does at closed throttle?(vac will increase to 17-20 or so at 1500-1800rpm)
*Another issue that goes right along with this is that when light throttle is used in nuetral to bring the rpms up to 2000, the engine will drop back to 1500 and then back up to 2000 in a cycle of rev/drop/rev/drop. Nice and smooth, rev/drop, rev/drop.
**When pressure checking the intake to the VG30, I can rolll the engine over to where all the valves are closed and pressurize the upper plenum/intake with @ 20psi of air and hear leakage. Soapy water shows me that the electrical end of the air regulator has the tiniest little seep, I can also hear the egr valve seep, but there's a fair amount of leakeage that can be felt with a damp hand down byside the throttle body(above cyclinder#6 spark plug). I can only get the intake to hold air for about 5 seconds before it all bleeds off. I know that it'll prolly loose some psi past the valves...but is the thing supposed to hold pressure for quite some time? What is acceptable?...If you've done this, post what it did for you.
~I'm puzzled!
Fact:
Cam grinds will effect the amount of vacuum an engine produces with the throttle closed.
I'm running the 270-62h cams and am seeing 12-14 vac. at idle(850-900rpm)
Question:
What explanation is there for an engine that produces more vacuum with a slight tip of the throttle than what it does at closed throttle?(vac will increase to 17-20 or so at 1500-1800rpm)
*Another issue that goes right along with this is that when light throttle is used in nuetral to bring the rpms up to 2000, the engine will drop back to 1500 and then back up to 2000 in a cycle of rev/drop/rev/drop. Nice and smooth, rev/drop, rev/drop.
**When pressure checking the intake to the VG30, I can rolll the engine over to where all the valves are closed and pressurize the upper plenum/intake with @ 20psi of air and hear leakage. Soapy water shows me that the electrical end of the air regulator has the tiniest little seep, I can also hear the egr valve seep, but there's a fair amount of leakeage that can be felt with a damp hand down byside the throttle body(above cyclinder#6 spark plug). I can only get the intake to hold air for about 5 seconds before it all bleeds off. I know that it'll prolly loose some psi past the valves...but is the thing supposed to hold pressure for quite some time? What is acceptable?...If you've done this, post what it did for you.
~I'm puzzled!
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