Re: 1956 Packard Executive in France
Posted by HH56 On 2023/3/28 10:18:25
In a stock car there are two vacuum lines supplying the wiper motor. One from the intake manifold -- or more properly, it is from a fitting on the base plate of the carb exposed to manifold vacuum -- for the main vacuum source. A second line comes from the aux vacuum pump that is in the crankcase. That line lays low on the right side of the block a bit above the oil pan and stops about in the middle with a 90 degree fitting threaded into the block. A small check valve is located a short distance away from the fitting.
Both lines go toward the firewall where a rubber hose connects them into the side of a balance valve screwed on the firewall. From that valve a hose goes to the wiper motor. If the optional windshield washer is installed another hose off the valve supplies vacuum to it.
With the crankcase aux pump removed it is important the second line is completely blocked off. Some who did the mod removed the balance valve and second line and added a plug in the block port. Others wanting to maintain a stock look left that part intact but capped the line that went to the aux pump either by blocking the rubber hose at the balance valve or by plugging the final 90 degree fitting into the block. Still others did neither and relied only on the continued functioning of the check valve in the aux line. With your aux pump gone it is important to make sure what ever was done to block the aux pump line is still intact and there is no possibility of a vacuum leak.
Almost all wiper motor vacuum comes from the intake manifold but when the engine is under load and vacuum drops, the aux pump is stronger and balance valve moves an internal mechanism to fully open that port and close the port to the intake manifold. The wipers do slow down since the aux pump does not have a large volume to run it at fast speed but they do keep going. With only manifold vacuum, there is a good chance wipers will stop if the engine is under a large load or throttle is wide open. Once the load is gone and full manifold vacuum is present the balance valve flips again to fully open the manifold port.
Most who did the PI mod with aux pump removal changed the fuel pump to a dual action type similar to the pumps used in 54 and earlier cars. The vacuum lines were rerouted and replumbed so manifold vacuum goes thru the fuel pump vacuum section just as was done with earler cars. A few just ran a hose from the old aux pump line to the inlet port on the fuel pump vacuum section keeping the balance valve functioning. While that may not be the best approach it is the most stock looking and does work. I believe there are pumps for some Ford Thunderbird engines that bolt right on the V8s. Perhaps someone can post the year pumps that will work.
Attach file:
balance valve.jpg (76.97 KB)
Both lines go toward the firewall where a rubber hose connects them into the side of a balance valve screwed on the firewall. From that valve a hose goes to the wiper motor. If the optional windshield washer is installed another hose off the valve supplies vacuum to it.
With the crankcase aux pump removed it is important the second line is completely blocked off. Some who did the mod removed the balance valve and second line and added a plug in the block port. Others wanting to maintain a stock look left that part intact but capped the line that went to the aux pump either by blocking the rubber hose at the balance valve or by plugging the final 90 degree fitting into the block. Still others did neither and relied only on the continued functioning of the check valve in the aux line. With your aux pump gone it is important to make sure what ever was done to block the aux pump line is still intact and there is no possibility of a vacuum leak.
Almost all wiper motor vacuum comes from the intake manifold but when the engine is under load and vacuum drops, the aux pump is stronger and balance valve moves an internal mechanism to fully open that port and close the port to the intake manifold. The wipers do slow down since the aux pump does not have a large volume to run it at fast speed but they do keep going. With only manifold vacuum, there is a good chance wipers will stop if the engine is under a large load or throttle is wide open. Once the load is gone and full manifold vacuum is present the balance valve flips again to fully open the manifold port.
Most who did the PI mod with aux pump removal changed the fuel pump to a dual action type similar to the pumps used in 54 and earlier cars. The vacuum lines were rerouted and replumbed so manifold vacuum goes thru the fuel pump vacuum section just as was done with earler cars. A few just ran a hose from the old aux pump line to the inlet port on the fuel pump vacuum section keeping the balance valve functioning. While that may not be the best approach it is the most stock looking and does work. I believe there are pumps for some Ford Thunderbird engines that bolt right on the V8s. Perhaps someone can post the year pumps that will work.
Attach file:
balance valve.jpg (76.97 KB)
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