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PCV Reroute

T

Thatslowvo

New member
Joined
Apr 29, 2018
I am in the process of swapping a B230F out of an 87' 740 into my 76' 242, and was curious on how i should vent the PCV. Read a thread about just running the stock breather box and running a line to a catch can to atmosphere. Is that something i could do? is there a better way? i will also be running the link provided carb setup.

Do i need a flame trap? do i need to vent the head?

www.classiccarperformance.com

Volvo b21 b23 b230 - 32/36 DGV or DGEV Weber Carb Conversion Kit

Volvo's b21 engine a.k.a the "Red Block" (1974-1985):Volvo 240, 260 Series Volvo's b23 engine (1979-1984):Volvo 240, 740 Volvo's b230 engine (1985-1995):Volvo 240, 740, 940 Increased performance can be derived by changing to Weber carbs - plain and simple. The downdraught DGV/DGEV carburetor...
www.classiccarperformance.com www.classiccarperformance.com
 
The breather box is a catch can, it drains collected oil to the sump and burns fumes in the intake. Plumb the breather box to the intake, install a flame trap between the two and you're set.
 
Radtap said:
The breather box is a catch can, it drains collected oil to the sump and burns fumes in the intake. Plumb the breather box to the intake, install a flame trap between the two and you're set.
Click to expand...
could i use the same port to take vacuum for the brake booster?
 
Thatslowvo said:
I am in the process of swapping a B230F out of an 87' 740 into my 76' 242, and was curious on how i should vent the PCV. Read a thread about just running the stock breather box and running a line to a catch can to atmosphere. Is that something i could do? is there a better way? i will also be running the link provided carb setup.

Do i need a flame trap? do i need to vent the head?

www.classiccarperformance.com

Volvo b21 b23 b230 - 32/36 DGV or DGEV Weber Carb Conversion Kit

Volvo's b21 engine a.k.a the "Red Block" (1974-1985):Volvo 240, 260 Series Volvo's b23 engine (1979-1984):Volvo 240, 740 Volvo's b230 engine (1985-1995):Volvo 240, 740, 940 Increased performance can be derived by changing to Weber carbs - plain and simple. The downdraught DGV/DGEV carburetor...
www.classiccarperformance.com www.classiccarperformance.com
Click to expand...
I've used this setup but with a genuine Weber 38/38. Don't do it.

The setup is designed as a replacement for the single or double downdraft solex carbs boats got and not really great for the average car. The problems are the following
  • There is not preheat capability in that manifold. With the hard right angle just after the carburetor you need some way to heat the manifold on cold start to prevent fuel from condensing on the manifold and not making it to the cylinder. This leads to a very bad off idle bog between 1000 and 2000 rpm until the manifold can warm up just from heat conducted from the head. This takes longer than you would think due to the length of the runners and the cooling effect of the fuel/air mixture rushing through it. There will be a point in the warm up process where the car really isn't drivable. The way around this is to jet the low end so it is very rich when choked (about 11:1 AFR) at which point you start risking washing oil off the cylinder walls.
  • The electric choke on the DGV/DGS carburetors opens too fast to counteract the manifold heating issue. You need a water operated choke but even that isn't enough.
  • The vacuum fitting on that manifold is often badly drilled and is an oddball M16 thread. I tried multiple methods of getting some form of PCV setup but found they all produced odd behavior with the carburetor.
I could go on about this but I'd consider this setup only good for a boat or racecar. In the latter case you might as well consider dual DCOEs.

Find a stock B21A, B23A, or B230A carburetor setup or retain the '87 EFI and make the needed modifications to the car to support it. There are three wires you have to hook up to the engine harness to run LH 2.0/2.2 on a K-jet car.
 
Radtap said:
The breather box is a catch can, it drains collected oil to the sump and burns fumes in the intake. Plumb the breather box to the intake, install a flame trap between the two and you're set.
Click to expand...
It isn't quite that simple. The stock breather on a B230 is set up to in a way that it can provide fresh filtered air to the crankcase and also pull excess fumes out to be burned. Otherwise you constantly put the crankcase under vacuum, which causes other issues.

Thatslowvo said:
could i use the same port to take vacuum for the brake booster?
Click to expand...
The challenge is that you are inducing a vacuum leak that has to be controlled in some way for the engine to run. The B230 approach was to take filtered air in after the MAF sensor but before the throttle plate. Air moving through the crankcase at the end was still metered by the MAF and had minimal impact on the engine's behavior.

Carbureted and K-jet cars relied on a very small and specifically sized restriction in a special vacuum fitting on the manifold to minimize the impact of the vacuum leak they introduced.

I'd look at how the carbureted redblocks, even the pushrod ones, set up their PCV system. If you are dead set on a carburetor.
 
Thatslowvo said:
I am in the process of swapping a B230F out of an 87' 740 into my 76' 242, and was curious on how i should vent the PCV. Read a thread about just running the stock breather box and running a line to a catch can to atmosphere. Is that something i could do? is there a better way? i will also be running the link provided carb setup.

Do i need a flame trap? do i need to vent the head?

www.classiccarperformance.com

Volvo b21 b23 b230 - 32/36 DGV or DGEV Weber Carb Conversion Kit

Volvo's b21 engine a.k.a the "Red Block" (1974-1985):Volvo 240, 260 Series Volvo's b23 engine (1979-1984):Volvo 240, 740 Volvo's b230 engine (1985-1995):Volvo 240, 740, 940 Increased performance can be derived by changing to Weber carbs - plain and simple. The downdraught DGV/DGEV carburetor...
www.classiccarperformance.com www.classiccarperformance.com
Click to expand...
If you are dead set on that configuration I'll sell you it for cheaper.
 
spock345 said:
I've used this setup but with a genuine Weber 38/38. Don't do it.

The setup is designed as a replacement for the single or double downdraft solex carbs boats got and not really great for the average car. The problems are the following
  • There is not preheat capability in that manifold. With the hard right angle just after the carburetor you need some way to heat the manifold on cold start to prevent fuel from condensing on the manifold and not making it to the cylinder. This leads to a very bad off idle bog between 1000 and 2000 rpm until the manifold can warm up just from heat conducted from the head. This takes longer than you would think due to the length of the runners and the cooling effect of the fuel/air mixture rushing through it. There will be a point in the warm up process where the car really isn't drivable. The way around this is to jet the low end so it is very rich when choked (about 11:1 AFR) at which point you start risking washing oil off the cylinder walls.
  • The electric choke on the DGV/DGS carburetors opens too fast to counteract the manifold heating issue. You need a water operated choke but even that isn't enough.
  • The vacuum fitting on that manifold is often badly drilled and is an oddball M16 thread. I tried multiple methods of getting some form of PCV setup but found they all produced odd behavior with the carburetor.
I could go on about this but I'd consider this setup only good for a boat or racecar. In the latter case you might as well consider dual DCOEs.

Find a stock B21A, B23A, or B230A carburetor setup or retain the '87 EFI and make the needed modifications to the car to support it. There are three wires you have to hook up to the engine harness to run LH 2.0/2.2 on a K-jet car.
Click to expand...
This is great info. Was originally going to find a replacement for my b21 and swap everything over because it ran great before the motor seized. Instead i was convinced that a carb'd B23 swap would be better.
 
Thatslowvo said:
This is great info. Was originally going to find a replacement for my b21 and swap everything over because it ran great before the motor seized. Instead i was convinced that a carb'd B23 swap would be better.
Click to expand...
It doesn't really make much sense to go from fuel injection to a carburetor if all the pieces for fuel injection are readily available.
 
Thatslowvo said:
the K-jet is half fuel injection half carb
Click to expand...
That's a bit of an oversimplification and there's really nothing in common between the way carbs and kjet function. Kjet is actually a pretty good system, especially the later O2 sensor and Constant Idle System equipped versions and when it's working properly it drives like any other fuel injected 240.

The main downside of running or restoring kjet now is the rarity and cost of good parts but that's why others here have suggested swapping to LH instead.
 
I've run an OHC redblock with all the systems discussed here. I really couldn't tell much of a difference between my K jet B21 versus an LH 2.4 B230 other than 2.4 having an IAC valve. This really just meant the idle would fluctuate a bit on the K jet car. The carburetor had me keeping track of temperature and conditions with every startup. With fuel injection it just worked.
 
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