Re: How to add a PCV Valve to a 1949 Packard

Posted by JWL On 2015/11/14 12:13:16

First of all, thanks to Packard 1948 for sharing his PCV installation on a 356 engine.

Intrigued by his installation, I decided to investigate and see what kind of results would be with PVC on my 115C's 237 six.

I bought a valve per Packard 1948. I made a test connection to the intake manifold fitting using the valve and some 3/8" fuel hose. I did not connect the other end with the PCV falve to the draft tube fitting. I started the engine and ran it until warm. It was obvious the valve was functioning. I adjusted the idle mixture and speed screws on the carburetor to get the smoothest idle. The engine would idle down, but it was not as smooth running as it was without the PCV valve.

While the idle was acceptable, I began to think that this PCV would be a vacuum leak throughout the RPM and load range. This bothered me as in order to overcome the lean mixture above idle would mean re-calibrating and re-jetting the carburetor. While the PCV may work well at burning crankcase fumes, the lean fuel mixture would probably cause problems. We know that a lean mixture can lead to poor performance, higher operating temperatures, and if bad enough burned valves.

I decided not to go forward with the PCV because of the leaned-out mixture and its effect on performance and wear.

Another option to positive crankcase ventilation would be to run a line from the draft tube connection to the air cleaner. Some sort of anti-backfire valve would need to be fitted in order to eliminate engine damage if the line is connected to the carburetor side of the filter element (maybe a PCV valve?). A valve would not be necessary if the line is connected to the outside of the filter element. However, with this connection crankcase fumes will contaminate the filter and it will require more frequent service. This low vacuum draw might be enough to purge the crankcase. This method was used on some vehicles in the past. This set up should not affect carburetor settings.

This was my experience, others may have different results.

(o{}o)