Filter or other solution for crank tube?

[Mike]

I'm no longer using SU carbs because I replaced them with Triple Mikuni's. My Mikuni's have three separate filters. Because of this swap, I now need to find a solution to cover the tube coming out of the engine (just below the carbs).

From what I understand, this tube is responsible for routing engine crank fumes/gasses back into the carbs for emission purposes.

I also have the same problem for the tube coming out of valve cover, but, I know there is a K&N solution for that part.

Does anyone have good ideas about how I can deal with the one for the engine crank? If you have pictures or ideas, it would help me out a lot !!

Thanks!

-- Mike

[240ZX]

Mike, K&N has a filter/breather for the lower vent tube as well.....IIRC, I got mine from MSA. Look at my avatar...just above the ignition coil.

Tom

[jmortensen]

The stock PCV system routes the crank to the intake, which basically creates a vacuum in the crankcase. Having this vacuum in the crankcase actually increases the rings' ability to seal against the cylinder walls and is a good thing, although running the oily air through the intake is not so good.

In order to get vacuum to the crank, I've seen guys make complicated manifolds to run the PCV to the triple manifold (Dan Baldwin and BJ Hines have done this, I'm sure many others have too).

Another option is to run a vacuum pump directly to the crankcase, and this can also be hooked to the brake booster if you have low vacuum.

Personally I never felt like the booster lost all that much when I went to triples, despite my decent sized cam. My solution to this lack of vacuum to the PCV is going to be one of these: http://www.jegs.com/webapp/wcs/stores/servlet/product_10001_10002_21252_-1

This is a simple one way valve that you install into the exhaust and hook to the PCV via a hose (on the V8 it routes to the valve covers). It routes the crankcase gasses to the exhaust pipe and uses the Bernoulli principle to suck the crankcase pressure out straight into the exhaust.