I am curious to know what would is causing my manifold vacuum pressure to continue to climb as engine RPM increases from idle.
I am only tuning the car in the garage at this point and have not tested while driving. All information I have collected (internet) says manifold pressure should began to decrease as you apply more throttle. Yet, my mine continues to go up!
Initial vacuum is 9-11 In Hg @ 900-1030 rpm & vacuum climbs to 20 In Hg as throttle increase to ~3500 rpm but never drops down. All measurements taken at the intake manifold port.
Build details:
Motor: 535CI Stroker,
Cam: Hughes Cam SER5458BL3-9, Duration 254 int., 258 exh. with lobe Separation@ 109 degrees.
Carb: Holley 750cfm with vacuum sec. (this is a rebuilt carb for engine startup & test. Planning to go to EFI);
Timing: 25 degrees initial; all in at 45 degrees at ~1700 rpm (dist. vacuum port not connected);
A/F ratio: Gauge reads 14.6-15.3 at idle & drops to ~13.5 at throttle.
Any help would be appreciate FBO.
Thanks, Will
I am only tuning the car in the garage at this point and have not tested while driving. All information I have collected (internet) says manifold pressure should began to decrease as you apply more throttle. Yet, my mine continues to go up!
Initial vacuum is 9-11 In Hg @ 900-1030 rpm & vacuum climbs to 20 In Hg as throttle increase to ~3500 rpm but never drops down. All measurements taken at the intake manifold port.
Build details:
Motor: 535CI Stroker,
Cam: Hughes Cam SER5458BL3-9, Duration 254 int., 258 exh. with lobe Separation@ 109 degrees.
Carb: Holley 750cfm with vacuum sec. (this is a rebuilt carb for engine startup & test. Planning to go to EFI);
Timing: 25 degrees initial; all in at 45 degrees at ~1700 rpm (dist. vacuum port not connected);
A/F ratio: Gauge reads 14.6-15.3 at idle & drops to ~13.5 at throttle.
Any help would be appreciate FBO.
Thanks, Will