Re: Dummy Timing Chain Install Question

Posted by HH56 On 2011/1/15 22:48:41

The pump is strictly a helper. Plumbed in series, normal manifold vacuum will always be stronger and will just suck air right thru the pump. When at open throttle or load, when vacuum falls off then the pump will be stronger--although nowhere near as strong as manifold normally is--and will take over to provide enough vacuum to keep the motor moving at a reduced speed. I don't recall seeing a complete diagram of the vacuum on pre 55.