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924-76
Joined: 05 Jun 2006 Posts: 1475 Location: Ontario, Canada
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Posted: Thu Apr 17, 2008 9:23 pm Post subject: Weber carbs question |
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Working on the weber 40 dcoe conversions and I don’t know what to do with the engine breather line that connects to the air box.
What you guys did with it?
Do you know if that line needs any sort of vacuum on it? |
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Chrenan
Joined: 15 Jan 2003 Posts: 3903 Location: Canada
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Posted: Fri Apr 18, 2008 12:05 am Post subject: |
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Even with my CIS I run that to atmosphere. I'd rather lose the vacuum on the crankcase than have all the crap recirculated through my intake. I fully understand the benefits of keeping a vacuum on the crankcase, but I could care less. I don't have any running issues, however, I have a very fresh engine rebuilt a couple of years ago with low kms. On a tired engine getting rid of the crankcase vacuum might cause increased blow by? _________________ 1987 951 - M193 Version for Japan |
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Rasta Monsta
Joined: 12 Jul 2006 Posts: 11723 Location: PacNW
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Posted: Fri Apr 18, 2008 2:02 am Post subject: |
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Yeah, no PCV can also cause rear main seal leaks - ask Porschev. _________________ Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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924-76
Joined: 05 Jun 2006 Posts: 1475 Location: Ontario, Canada
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Posted: Fri Apr 18, 2008 3:01 am Post subject: |
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So, to be safe I should keep that line on vacuum?
Any recommend setup?
Any picture from any one who are running the weber would be appreciated. |
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Rasta Monsta
Joined: 12 Jul 2006 Posts: 11723 Location: PacNW
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Posted: Fri Apr 18, 2008 3:34 am Post subject: |
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When I had Webers on my 914, I bought nylon elbow fittings and drilled holes to take them in both air cleaner lids. I then teed it together and to the CCV. _________________ Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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924-76
Joined: 05 Jun 2006 Posts: 1475 Location: Ontario, Canada
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Posted: Fri Apr 18, 2008 3:47 am Post subject: |
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What do you thing if I put a small filter (like a carbs full filter type) on the line and connected the line with the brake booster vacuum line. |
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Rasta Monsta
Joined: 12 Jul 2006 Posts: 11723 Location: PacNW
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Posted: Fri Apr 18, 2008 3:54 am Post subject: |
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You don't want to put manifold vacuum on the crankcase. Use the air cleaners or nothing as Chrenan did (at the risk of oiling your clutch).
If you use nothing, I seem to recall somebody (K&N maybe) selling a mini-air filter for your breather hose that looks pretty cool (but is entirely non-functional). _________________ Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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924-76
Joined: 05 Jun 2006 Posts: 1475 Location: Ontario, Canada
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Posted: Fri Apr 18, 2008 4:01 am Post subject: |
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The line is presently attached to the air box behind the air filter.
The way that air box is designed, is that would be the same vacuum then at the manifold? |
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fiat22turbo
Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR
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Posted: Fri May 02, 2008 7:40 am Post subject: |
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Nope, the vacuum behind the throttle plate is higher than behind the air filter.
If you want to get fancy, you can add a vacuum barb to the exhaust and pull vacuum that way. There are kits for this since you have to get the barb in the exhaust at the right angle and depth to work properly. Drag racer love the fact that it increases the vacuum in the crank case, helping the rings seal, among other things. _________________ Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
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AppleBit
Joined: 16 Nov 2002 Posts: 1516 Location: Minneapolis, MN
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