Question about oil catch cans and breathers

[T-Bone028]

Whats up everyone, I'm working on building a DIY oil catch can and had a few questions about plumbing everything up. Here's my current PCV (factory) system.

 

1) Breather from block connected via hose to PCV valve on intake manifold.

2) Breather vent on valve cover routed to airbox cleaner via hose.

 

Essentially, my set-up is just like the factory, just minus all the other emissions control devices like air pump and air injection into the exhaust. The other day, I noticed I was getting a lot of blow by coming from my valve cover breather line. Since it is hooked up like the factory system, this means that blow-by gas is being pointed directly into my rear SU carb. I cant imagine this is an ideal situation for my carb and A/F mixture. According to the FSM, in most throttle conditions other than WOT, the breather from the valve cover should be picking up filtered air from the airbox, letting it flow through to the bottom of the crankcase, mixing with blow-by gas, and eventually being pulled and re-burnt through the pcv valve into the intake manifold. I replaced my PCV just yesterday thinking that it should fix the blow-by problem, but it did not.

 

So, now I'm considering running an oil catch can. I believe the normal set-up is:

 

1) vent line from block to catch can

2) vent line from catch can to pcv valve on intake manifold

3) valve cover vent can either be vented with a breather, or plumbed into the air cleaner

 

Since I dont want all the blow by gas going into my air cleaner/carb, I was thinking about introducing a "T" fitting to the catch can. One end of the T would go to the catch can, the other end is hooked up to the block vent line, and the last "T" end would be hooked up with the valve cover vent line. So, both block and valve cover vents would be run to the catch can, the blow-by gas would get filtered, and then fed back into the PCV valve on the intake manifold to be burned. I will also use a PCV valve inline on the hose from the valve cover vent line so blow by gas can only be pushed out of the valve cover, and not back in.

 

Does anyone foresee any problems with this? I think it will work, but I'm just not sure. So far, I've spent about $45 on various barb fittings/elbows, hose, and a heavy duty air compressor air filter http://www.sears.com/shc/s/p_10153_12605_00916009000P?vName=Tools&cName=AirCompressors&AirTools&sName=Air%20Compressor%20Accessories&psid=FROOGLE01&sid=IDx20070921x00003a

 

Your thoughts?

Edited May 6, 2010 by T-Bone028

[Alxxpress]

I run a large exhaust check valve to my exhaust or down pipe for vacuum.

[dhartig]

I picked up a Hong Kong catch can off Ebay and will put it in with the same routing. BTW I was impressed with the product and delivery. Good quality polished aluminum finish with all barbs and hoses plus attachment fittings for less than $45. Probably half of that went for the air freight costs.