Twin SU PCV

[SloRolla]

G'day fellas, I've recently picked up a 5k and twin SU carbs. I have stripped the carbs down and cleaned them up. However, I can't see how the PCV hose will have it's run off. What way are they normally hooked up? A catch can? (AltezzaClub? I've read how you set up yours, but I couldn't see the vavle)

Cheers!

[parrot]

Wouldn't the PCV feed into your aircleaner setup, as it does factory?

That way the gases and crap get reburnt and don't gunge up the carbs.

Generally people feed it into a catchcan though

[SloRolla]

3 minutes ago, parrot said:

Wouldn't the PCV feed into your aircleaner setup, as it does factory?

That way the gases and crap get reburnt and don't gunge up the carbs.

Generally people feed it into a catchcan though

Cheers for the reply Parrot, There is actually no way I can put it into the air cleaner, (unless I build an airbox). I'll be running trumpets, so I guess i'll run a catch can.

[parrot]

Once you see what ends up in the can, you’ll be pleased it isn’t going through the carbs. But make sure you empty it regularly

[rebuilder86]

What PCV system sends pcv gas through the air filter? Or even tgrough the carb? thats retarded and it wont even work. it needs vacuum.

PCV goes to the manifold.

Fresh air is supplied to the rocker from clean air after the air filter, and during deceleration, it can spit back some gunk up the fresh air tube.

[parrot]

No, it feeds to the INSIDE of the air filter element and is drawn through the carb. Have a look at an air cleaner thingy, and you will see the mesh covering the inlet into the induction system. 

It doesn’t get drawn through the air filter. 

[parrot]

Like this

The small grille area at the top is where the PCV hose from a 3K  engine feeds to the filter housing INSIDE the filter element. 

It then gets drawn through the carb by the engine induced vacuum

[SloRolla]

But isn't that the rocker breather and not the PCV? I thought that was for the port more to the front in the middle, where as the PCV is further back

[parrot]

Yes, often it feeds into the manifold.  But in your situation it doesn't matter, as you preferably feed it into a catch can anyway. 

 

The rocker space and the crankcase are in reality connected, so pressure within the engine's non combustion areas should effectively be equal anyway.

[SloRolla]

38 minutes ago, parrot said:

Yes, often it feeds into the manifold.  But in your situation it doesn't matter, as you preferably feed it into a catch can anyway. 

 

The rocker space and the crankcase are in reality connected, so pressure within the engine's non combustion areas should effectively be equal anyway.

Mint, I'll order a catch can soon

[parrot]

Here’s a good post that discusses the situation in detail, and how the K motor only had the one outlet for example

 

[SloRolla]

26 minutes ago, parrot said:

Here’s a good post that discusses the situation in detail, and how the K motor only had the one outlet for example

 

I see, so running the catch can runs fine, how would I hook the brake booster up? Altezza said about T'ing it in. What's your thoughts? Also. Is this how you would hook the can up? Sorry about all the questions. I haven't had much luck with searching, and I don't want to cook my newly aquired 5k haha

[altezzaclub]

Drill & tap the Lynx  manifold, I did it when I moved the brake booster inlet so I could fit the extractors on.

That gives you brake booster vac, and as you said I T-pieced the PCV line into that so they both had full vac. Later I added a separate vac line for the PCV.

The second tappet cover line goes to the inside of the air filter so it draws filtered air into the engine as the PCV draws dirty air out. When you're idling the dirty air goes into the air filter as the PCV is shut then.

You could just catch tank the breathers, but if you don't have the Lynx vac inlet for the brake booster you'll have to drill it anyway.

 

PM me if you'd like to borrow the drill & tap for that fitting.  You can see where I blocked off the hole that was in the Lynx when I bought it, and re-located it to the edge.

The PCV now goes in the middle of  the Lynx manifold.

 

 

[SloRolla]

54 minutes ago, altezzaclub said:

Drill & tap the Lynx  manifold, I did it when I moved the brake booster inlet so I could fit the extractors on.

That gives you brake booster vac, and as you said I T-pieced the PCV line into that so they both had full vac. Later I added a separate vac line for the PCV.

The second tappet cover line goes to the inside of the air filter so it draws filtered air into the engine as the PCV draws dirty air out. When you're idling the dirty air goes into the air filter as the PCV is shut then.

You could just catch tank the breathers, but if you don't have the Lynx vac inlet for the brake booster you'll have to drill it anyway.

 

PM me if you'd like to borrow the drill & tap for that fitting.  You can see where I blocked off the hole that was in the Lynx when I bought it, and re-located it to the edge.

The PCV now goes in the middle of  the Lynx manifold.

 

 

You absolute legend! i'll take my manifold to the machinist and get 2 ports tapped, (cheers for the offer of the drill and bit) I'm going to run 2 ports like you did. Cheers heaps. this makes it a lot easier!

Edited December 10, 2017 by SloRolla

[rebuilder86]

On 09/12/2017 at 4:02 PM, parrot said:

No, it feeds to the INSIDE of the air filter element and is drawn through the carb. Have a look at an air cleaner thingy, and you will see the mesh covering the inlet into the induction system. 

It doesn’t get drawn through the air filter. 

nah parrot, the fresh air comes from the air filter housing, the PCV doesnt feed into there, if thats how its setup on urs its been setup wrong.
That little meshed filter is supposed to be stoppign solids from entering the PCV breather hose, which should be on the other side of that. Thats why its inside the filter, so that the fresh air supply is filtered.
The pcv valve wont open from the "at rest" backfiring position unless it has vacuum pulling on it.

To get the catch can to work, you must pull the PCV gasses into it, by sucking through the catch can with vacuum.
If you don't have a vacuum source involved in your catchcan setup, you are completely wasting your time and risking having nastys building up in the crankcase, , and greatly increasing oil consumption.
If you want to run a catch can setup it has to be like this
Sorry bout the poor graphics haha MS paint can only do so much

 

Edited December 10, 2017 by rebuilder86