The Ford Barn

Fordlane Wayne · 07-08-2010, 03:02 PM

I tested the vacuum on the Model A with a gauge placed in the hole on the intake manifold and have the following reading. The needle rapidly moves 7 inches above and below 20 inches when the car is at full advanced idle speed. It moves around 5 inches above and below 20 inches when the car is running at full retard idle speed. Does anyone know what this is telling me? At high rpm it's pretty steady at around 20 inches. I'm running a high compression head with between 86 to 90 lbs compression in all cylinders. The engine was restored around 1988 and has less than 2,000 miles on it according to my knowledge. Any suggestions would be appreciated. Thank you.

07-08-2010, 03:02 PM	#1
Fordlane Wayne Junior Member Join Date: Jun 2010 Location: Ashland, MA Posts: 9	Vacuum Gauge Testing I tested the vacuum on the Model A with a gauge placed in the hole on the intake manifold and have the following reading. The needle rapidly moves 7 inches above and below 20 inches when the car is at full advanced idle speed. It moves around 5 inches above and below 20 inches when the car is running at full retard idle speed. Does anyone know what this is telling me? At high rpm it's pretty steady at around 20 inches. I'm running a high compression head with between 86 to 90 lbs compression in all cylinders. The engine was restored around 1988 and has less than 2,000 miles on it according to my knowledge. Any suggestions would be appreciated. Thank you.