z32chick's 620 build

[Z23T]

Nice job getting the truck back on the road.

 

Here is the thread about the Datsun powered boats. 

 

[z32chick]

I must have been a really good girl this year!

 

 

 

 

 

Anyone else have people that love you and support your love for Datsun??

[datzenmike]

 

You really should get your PCV valve working correctly. The PCV should be screwed into the intake below the carburetor on the left side and the hose from the bottom block vent connected only to it. The valve cover vent hose goes to a plastic elbow on the front left underside of the Weber air filter base. Weber does sell them. The vacuum supply to the brake booster should be a single hose from the intake.

 

Defeating the PCV like that will shorten the life of the engine. Before the PCV was introduced in '62 oil change intervals were every 3,000 miles. After, they were extended to 6,000-7,000 miles because this is how much cleaner the engine will run and oil will last. '50s and earlier engines were exceptionally lucky to last to 100,000 miles.  

 

 

[z32chick]

I will take a look at it Mike.  I understand how important the PCV system is, but don't fully understand everything about vacuum and why it can't all be joined together as long as the air is moving in the right direction.  The searching and research I did when putting the truck back together lead me to the current setup, I had no intention to bypass/defeat the PCV.

[datzenmike]

First of all both ends of the crankcase are joined to a vacuum source so there is no fresh air entering the engine.

 

In operation the PCV mounted on the intake slowly vacuums water, oil and gas vapors and any combustion gasses and directs them into the engine to be burned. As these gassed are removed, filtered make up air from the air filter housing is drawn into the valve cover vent hose to displace them.  Often under heavy load and/or high RPM conditions, more blow by from the rings over powers the PCV valve system and the flow reverses. Here the gasses travel out the valve cover vent hose and inside the air filter where they are sucked down the carburetor and burned. It's an elegant system, and though taken for granted, is actually an ingenious idea. Has no effect on running but everything to do with keeping the engine clean.

 

All the vapors removed would normally condense over night as the engine cools and this would contaminate the oil. Part of the combustion process involves heat, nitrogen (in the air)and sulphur (in the gas and oil) that is formed into acids. Water vapor becomes water. None of this is good for lubricating and why the oil needs to be replaced more often