What do you do with the breather after installing velocity stack?

[Oilpan4]

I'll probably stick the hose under the foam outer cover for now then plumb it into the bend of the air filter elbow later.
What do you do with it?

 

[ezcome-ezgo]

Ok. Go for it.

 

[bob58o]

Why put it back into the intake?
Emissions control?

You are talking about the hose from the valve cover?

I usually find some kind of breather filter and modify the stock hose if needed. I don’t remember the hose size or size of filter that works best.

 

[Denny]

Because with it back in the breather he will have less chance of an oil leak, and his engine will last longer too!

 

[Oilpan4]

I figure it allows the engine to burn any gasoline blow by. It's only a stage 1 engine, intake, timing advanced, governor increase limited by UT2 coil, slight compression increase and exhaust. Not worried about a little bit of oil causing pre-ignition.

 

[Oilpan4]

 

[Hellion]

You can vent it straight to the ground, like they did with the old cars (before EGR, PCV valves and such). They didn't use catch cans either :

In the twenties (and probably even before) through the early sixties, engine air flow depended on a simple road draft tube. A metal tube, connected to the crankcase, was brought down near the bottom of the oil pan. The rear-facing half of the tube was cut at an angle, so that forward motion of the car created a small amount of reduced pressure, compared to the atmosphere.

https://mossmotoring.com/crankcase-ventilation/

In other words, all the moisture and combustion by-products (gasoline, oil mist, water vapor etc) was allowed to vent out of the engine and into the environment. I imagine the roads were maybe a bit more coated with engine by-products back then than nowadays but all combustion engines still leak and there's a dark stain down the middle of all freeways and highways to prove it.

Still, most of what came out of the road draft tube was vapor unless it is allowed to collect and condense.

 

[Master Hack]

Ghetto fab catch can?

 

[Oilpan4]

I figure it can add oil spray to the air filter and reburn any blow by.
It's barely even a stage 1 build.

 

[Hellion]

All the older industrial engines with a one-way breather valve (Briggs flathead for example) pumped the effluent right back into the carburetor, but downstream of the air filter. It was not blown into the air filter but under it or past it.

From a pure performance standpoint, it's not what you want pumped back into the engine (even though it may contain unburned fuel) the rest is vaporized moisture (H2O) that had collected in the crankcase oil, oil vapor that blew by the rings or the valve seals/stems (there's always a tiny amount) and various particulates, combustion by-products and maybe dirt that got in past the air filter or bad gasket. Reminder to make sure your air filter is good.

Ever see some guys racing around without an air filter? There's tons of them who claim "it runs better".

 

[Hellion]

Ghetto fab catch can?

That's hardly ghetto, Master Hack, that looks first rate and proper. Ghetto is just a piece of old tubing dangling in an empty soup can that's duct taped to a frame member.

 

[Denny]

That's hardly ghetto, Master Hack, that looks first rate and proper. Ghetto is just a piece of old tubing dangling in an empty soup can that's duct taped to a frame member.

That’s what he had before.

 

[Master Hack]

Ghetto is just a piece of old tubing dangling in an empty soup can that's duct taped to a frame member.

Just upgraded from that setup!

 

[Oilpan4]

Well I won't need to spray the k&n style air filter with oil ever again.

 

[bob58o]

All the older industrial engines with a one-way breather valve (Briggs flathead for example) pumped the effluent right back into the carburetor, but downstream of the air filter. It was not blown into the air filter but under it or past it.

I was thinking about doing this. My carb has a passage in the air horn (used for a power jet). I could run a line from the valve cover to the catch can then a tube from the top of the can back to the air horn.

Wouldn’t the pumping action of a single cylinder cause the block to pull air in from the air horn every compression stroke.

I was thinking it would mess up air flow in the air horn. Assuming there is some type of intake inertia tuning, I figured it might be disturbed.

 

[BrownStainRacing]

I was thinking about doing this. My carb has a passage in the air horn (used for a power jet). I could run a line from the valve cover to the catch can then a tube from the top of the can back to the air horn.

Wouldn’t the pumping action of a single cylinder cause the block to pull air in from the air horn every compression stroke.

I was thinking it would mess up air flow in the air horn. Assuming there is some type of intake inertia tuning, I figured it might be disturbed.

I use 2) one way check valves to keep the crankcase pressure as low as possible.
Pressure goes out when the piston is coming down. Air does not get pulled in when the piston is on its way back up, with one way check valves.

You could put 1 between the valve cover and catch can.

When that blower starts huffin, you might need to make more vent holes in the block and valve cover for more check valves,

I don't like the idea of contaminated air being pulled into the fresh air intake.

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[bob58o]

I use 2) one way check valves to keep the crankcase pressure as low as possible.
Pressure goes out when the piston is coming down. Air does not get pulled in when the piston is on its way back up, with one way check valves.

You could put 1 between the valve cover and catch can.

When that blower starts huffin, you might need to make more vent holes in the block and valve cover for more check valves,

I don't like the idea of contaminated air being pulled into the fresh air intake.

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I forgot who mentioned it, but I liked the idea of running a vent/vacuum line to the exhaust using the exhaust flow to pull out air from the block.

Ive got 2 vent locations in the block (governor hole and side cover) and two in the valve cover. I like the check valves.

 

[BrownStainRacing]

I forgot who mentioned it, but I liked the idea of running a vent/vacuum line to the exhaust using the exhaust flow to pull out air from the block.

Ive got 2 vent locations in the block (governor hole and side cover) and two in the valve cover. I like the check valves.

When you get it up and running, use 1 of those ports to install a vacuum/pressure gauge and see for yourself how much pressure is actually under that piston as it is moving up and down.

I was seeing as much as 20 psi spikes on the gauge with the stock valve cover and baffle as the rpm was at a steady 4500.
The stock pcv is jus not designed to work at that higher rpm, on these lil turd motors.

I found that 2 check valves had the same results as 3 or more, but that's for N/A engines that I tested.

 

[Oilpan4]

I get a lot of volume at idle and hardly any at 4,000.
The way the crank seals are installed you some positive pressure inside the engine.