COE Dan
Senior Member
Hello,
I am trying to correct some problems on my car and am using a vacuum gauge to evaluate performance. I have a chart showing what different readings mean but I need help interpreting my results.
Here's the background:
- At idle, gauge reads 15-17 inches Hg in neutral, 14-16 in gear.
- At all engine speeds, there is a rythymic half-inch Hg drop accompanied by a noticeable hiccup every so often (not consistent, random fluctuation)
- RPM fluctuates when vacuum fluctuates
- ambient air temp: 95F; sea level
- timing/dwell are in specs
What I would like to know:
1) my chart says normal engine range is 17-21 inches - can the high air temp equate to a lower reading like I am observing?
2) what does the 1/2 inch random drop in vacuum tell me? (I think it is too small and not consistent to be a valve issue; it's not low and steady like a vacuum leak would have)
3) I think there may be excess fuel entering the intake, the carb to intake gasket shows staining and is wet - would this account for the minor fluctuation in RPM/vacuum?
Thank you much,
Dan
I am trying to correct some problems on my car and am using a vacuum gauge to evaluate performance. I have a chart showing what different readings mean but I need help interpreting my results.
Here's the background:
- At idle, gauge reads 15-17 inches Hg in neutral, 14-16 in gear.
- At all engine speeds, there is a rythymic half-inch Hg drop accompanied by a noticeable hiccup every so often (not consistent, random fluctuation)
- RPM fluctuates when vacuum fluctuates
- ambient air temp: 95F; sea level
- timing/dwell are in specs
What I would like to know:
1) my chart says normal engine range is 17-21 inches - can the high air temp equate to a lower reading like I am observing?
2) what does the 1/2 inch random drop in vacuum tell me? (I think it is too small and not consistent to be a valve issue; it's not low and steady like a vacuum leak would have)
3) I think there may be excess fuel entering the intake, the carb to intake gasket shows staining and is wet - would this account for the minor fluctuation in RPM/vacuum?
Thank you much,
Dan
