PCV Valve on a 359

Posted by Warren J. Erickson On 2009/9/4 14:32:22

Hi All:

Has anyone installed a PCV Valve on their straight eight? Reason asking: I just completed a valve job on my 359. I was surprized at the amount of sludge in the Tappet Chambers. Also the valve springs and washers had some surface rust. And I had 3 stuck valves. I suppose this is due to not running the beast long enough to get it really up to temperature. Blowby and oil consumption, on this engine, is not bad. The last time I had the head off was about 15 years ago.

Years ago, I experimented with this on a 51 327. I read, at the time, that this was mandatory in California. Regardless of the year. As I recollect, the experiment was successful. With no noticeable change in driveability. Although I did not have this car log enough for a long term evaluation. Anyway, my rational was, this system has to be much more efficient than the road draft tube.

I'm hesitant to try this on my Pacific. As it's not a rust bucket. Like the 51 was. I know the concept of a PCV Valve. It induces a small vacuum in the crankcase at high manifold vacuum (Idle). And a much larger vacuum at low manifold vacuum (Load). The idle vacuum is not concerning. As I recollect, I didn't even have to re-adjust the idle mixture screws on the 51.

My concern is the larger vacuum under load. What does this do to carburetor jetting? And overall lean running? That might be detrimental to the exhaust valves.

Furthermore; As you know, these engines use the old rope seals for crankcase sealing. Will they stand up to a negative pressure in the crankcase?

My main objective is to obtain better breathing in the Tappet Chambers. As I use this car infrequently. And possibly reduce the above mentioned issues.

Your thought?

Thanks