Page Last Updated 05 June 2005
The road draft tube survived many years as Chevy's way of eliminating crankcase gasses so most of us don't consider changing anything, but it has its drawbacks. It's dirty, it leaks a small amount of oil onto your clean driveway, and it's hard to clean properly. Enter the Positive Crankcase Ventilation System! PCV is really simple. It simply means pulling the gases out of the crankcase using the engine's vacuum pressure.
In the case of the 216, 235 or 261 engine, you simply remove the road draft tube and install a 1-1/4" Freeze Plug with a hole in the center big enough to accomodate the PCV Valve. The plug fits in really snug so it's perfect. You then install the grommet, which is availabe at any good local automotive parts store, right inside the cup of the freeze plug. I used Permatex High-Temp Copper Gasket Sealer on the inside of the freeze plug (using your little finger, you should be able to get to it) and around the grommet to better hold it in place. It's the perfect fit, so it's not going anywhere anyway. At this point, you simply push the PCV Valve in and this step is complete.
Note: There are two ways of doing this installation. If you are worried about the PCV Valve being too close to the crankcase (thus possibly sucking oil into the system,) instead of drilling a large hole to fit the valve, drill a hole the size of a 3/8" male hose fitting and then put the PCV Valve inline somewhere. This would eliminate the need for the grommet completely.
The Valve is Standard Brand V-178 and we are using 3/8" PCV/Fuel Line hose. I needed about 4 feet. The concept is to connect the PCV Valve via the hose to the intake manifold's vacuum inlet. If you are using that for windshield wipers, you have a problem that can be solved by installing a fuel pump that comes equipped with a vacuum inlet. Those are available through our vendors, or, take this opportunity to install electric wipers in your truck!
I wanted a clean installation, so I purchased new fittings to accomodate the 3/8" hose. Simply hook up the PCV Valve via the hose to the intake manifold, and you have just installed your very own PCV system! The experts tell me this is much, much better for your engine, and will extend the life of it. They also say you need to lean the fule mixture out a little during setup. I have not as of yet tested this system, because this truck is in the process of getting a frame-up restoration, and it may be months before I can actually try this. This modification is cheap and doesn't hack up your truck in any way, so there is no harm in trying it. Anyone trying this, please let me know how it works!
