PCV valve

[80tasmin]

The 280 engine on my Tasmin has been converted from fuel injection to carburation (Holley 600) and the PCV valve? on the valve cover is connected to the air filter. Nothing going to the intake manifold.
I've been told that this setup is OK, and that connecting the PCV valve directly into the manifold may result in a lean mixture that may damage the engine. Any thoughts? It's been suggested that I leave it the way it is.
Thanks, Paul

[GreenV8S]

Are you sure it's a PCV check valve? If so, I would have expected it to be plumbed in downstream of the throttle (hence providing 'positive' ventilation). An unrestricted breather would be plumbed in upstream (in the EFI setup, there's also a restricted breather connected downstream of the throttle).

[80tasmin]

GreenV8S said:

Are you sure it's a PCV check valve?

I've been told it's the PCV valve, but must admit my knowledge is very limited.
Here is another picture, showing a bit more of the setup, along with a photo of the other side of the engine....

Edited by 80tasmin on Wednesday 1st July 23:50

Edited by 80tasmin on Wednesday 1st July 23:54

[Comadis]

on the cologne injection engine this hose is routed towards the plenum chamber.

is there another breather on the cologne-block? i guess not.


so for me it does look ok to go this way as pictured.

did you do the injection-carb conversion?

[GreenV8S]

I'm not sure, but it looks a bit small to be a PCV check valve. I've seen one-way check valves around that size, but I don't understand why you would want one on an NA car. Perhaps it's just being used as a flame trap?

[80tasmin]

Comadis said:

did you do the injection-carb conversion?

All work was done by the previous owner.
Paul

[Comadis]

the injection engine does not have a filler cap with a hose routed to the carb.

maybe thats your problem?

on the original setup the engine draws the air through the cap (left side) and is venting through the valve (right side) towards the airfilter/carb or plenum chamber.

Edited by Comadis on Friday 3rd July 08:23

[Wedg1e]

80tasmin said:

GreenV8S said:

Are you sure it's a PCV check valve?

I've been told it's the PCV valve, but must admit my knowledge is very limited.
Here is another picture, showing a bit more of the setup, along with a photo of the other side of the engine....

Edited by 80tasmin on Wednesday 1st July 23:50

Edited by 80tasmin on Wednesday 1st July 23:54

It is indeed the PCV. It's plugged-in to a rubber grommet in the valve cover (the grommets go hard and stop sealing, by the way).
In the second pic... that braided hose leading from the oil filler cap: does it go to the airfilter, or somewhere upstream of the cab (ie engine side)?
What normally happens on the injection (as Comadis says) is that a portion of the metered air is drawn through that hose, through the filler cap and sucks the crankcase fumes out through the PCV. So the air is 'accounted for' by the injection. With a carb setup, drawing air from downstream of the carb will effectively be adding air to the mixture that the carb hasn't 'seen', so yes, you would have a potential for a weak mixture.
That said, the PCV is spring-loaded so it only opens under certain manifold depressions (over-run, mostly, I guess) so it probably wouldn't be an issue.
If the braided hose is tapped off 'after' the carb then probably not an issue; some of the air is merely taking a longer route to get into the cylinders.
I suppose the ony way to be sure would be to have full fuelling diagnostics run on it.

[80tasmin]

Wedg1e said:

It is indeed the PCV. It's plugged-in to a rubber grommet in the valve cover (the grommets go hard and stop sealing, by the way).
In the second pic... that braided hose leading from the oil filler cap: does it go to the airfilter, or somewhere upstream of the cab (ie engine side)?.

Yes, that braided hose does go into the air filter. What seems to be happening in this setup is that I've got two hoses connected to the air filter, with the hose on the "PCV valve" blowing oil into the air filter.
That just isn't right. So, today I will connect the PCV valve to the intake manifold, where, I guess, it should have been in the first place. (The port on the intake manifold had a rubber cap on it.)

Paul

Edited by 80tasmin on Friday 3rd July 13:56

[GV]

On my setup the PCV is used for positive breathing going into the rocker cover.

[Comadis]

here the injection engine: