Silly Question #2 - Where the Hell is the PCV Valve? (1 Viewer)

[Tony_Farson]

Hey Folks! So the PO stated that there was no PCV because the valve cover had no provision for one... Right. I THINK I found the hose for the PCV, but I do not see a bung for it anywhere. Was the PO correct? Do I need to tap a whole? Please forgive any ignorance I am showing in asking this question.

See pics:

Thanks!

 

[spotcruiser]

Not a dumb question. That is your pcv and it would have run to the base of your stock carb. It looks like you have a Weber carb, so it must have a different base plate. You can probably adapt the existing base plate. I have no experience with Webers, though, so I don't know what they use for a baseplate.

I do notice that you have a hose from the valve cover running to the DS of your carb. Where is that hose terminated?

Here's a diagram from SOR.

 

[spotcruiser]

By the way, if you search Weber and pcv, you might bring up a thread from the past showing what someone else did to reconnect their pcv with a Weber install.

 

[bb67tlc]

I don't know if the base plate is different from stock, but here's the none for my weber, with the pcv hose connected.

 

[Tony_Farson]

Not a dumb question. That is your pcv and it would have run to the base of your stock carb. It looks like you have a Weber carb, so it must have a different base plate. You can probably adapt the existing base plate. I have no experience with Webers, though, so I don't know what they use for a baseplate.

I do notice that you have a hose from the valve cover running to the DS of your carb. Where is that hose terminated?

Here's a diagram from SOR.

Thanks! I was wondering the same thing about that hose on the carb. Here's a better pic (maybe).

It goes between the VC and the base of the carb, I don't see why this couldn't house a PCV valve. Would there be some other purpose?

On another note, there is no choke connected to this carb and it seems to run rich (probably to make sure it starts and runs when cold without the choke). I don't know why they wouldn't have connected the choke or bypassed a PCV.

 

[Tony_Farson]

I don't know if the base plate is different from stock, but here's the none for my weber, with the pcv hose connected.

View attachment 1620455

That's a good lookin engine! It looks like your base is a bit different from mine. So there is a hose coming off your air cleaner that goes into the vc. That's just a breather right? The hose your are talking about is right near where the intake and carb meet? Is that your PCV?

 

[middlecalf]

The hose coming off of the PCV valve on the oil fill tube (circled item in the pic in your first post) needs to go to vacuum before the intake, hence usually connected at the base of the carb. If there is another plugged hole on the intake you could put a hose fitting in it and connect that hose to the fitting. The PCV valve, if working properly, ensures that air only goes one way (from lower engine to upper engine/intake) otherwise you could potentially suck fueled air mixture into the lower engine block - not good.

The hose coming off of the valve cover is a breather line (not vacuum) so it connects before the carb and should definitely be filtered air if running in any dusty environment, hence usually connects to a port on the air cleaner after the air is filtered. bb67tlc shows how to connect to your type of air cleaner (I'm assuming they're the same). This breather working in conjunction with the PCV line ensures clean air is moving through the non-combustion parts of the motor.

 

[David70FJ40]

Here is mine. The hose from the PCV is connected to the base of the Weber carb.

 

[Tony_Farson]

The hose coming off of the PCV valve on the oil fill tube (circled item in the pic in your first post) needs to go to vacuum before the intake, hence usually connected at the base of the carb. If there is another plugged hole on the intake you could put a hose fitting in it and connect that hose to the fitting. The PCV valve, if working properly, ensures that air only goes one way (from lower engine to upper engine/intake) otherwise you could potentially suck fueled air mixture into the lower engine block - not good.

The hose coming off of the valve cover is a breather line (not vacuum) so it connects before the carb and should definitely be filtered air if running in any dusty environment, hence usually connects to a port on the air cleaner after the air is filtered. bb67tlc shows how to connect to your type of air cleaner (I'm assuming they're the same). This breather working in conjunction with the PCV line ensures clean air is moving through the non-combustion parts of the motor.

Here's some pics of around the carb and intake. I think I found the spot it is supposed to be...

Behind the carb close up of blocked off bung.

Behind the carb (zoomed out)

In front of the carb (zoomed out)

Close up of the base of the carb

What do you guys think? Does the blocked off bung look like it would do the trick for a PCV?

 

[middlecalf]

Couple of options. Yes, you can use that spot on the intake manifold. But if you ever need another vacuum source that's what that's for. At a minimum I'd make a better seal/plug for that so it doesn't turn into a vacuum leak.

The better thing would be to put a brass or copper fitting into the base of the carb where that plug is (see pict). Then put the hose on that, it will be like David1947's.

 

[Tony_Farson]

Couple of options. Yes, you can use that spot on the intake manifold. But if you ever need another vacuum source that's what that's for. At a minimum I'd make a better seal/plug for that so it doesn't turn into a vacuum leak.

The better thing would be to put a brass or copper fitting into the base of the carb where that plug is (see pict). Then put the hose on that, it will be like David1947's.
View attachment 1620595

Excellent! I went ahead and connected it to the spot on the intake I found for now. I need to find the right fitting for that spot on the carb base. I am also looking for a new(ish) pcv valve, but they appear to be discontinued? The one that's on there looks like it is about 50 years old and the valve seems to be stuck open, so not sure how much good it is doing. However, I did notice the engine running smoother too. So who knows... that could be in my head!

Anyone know a source for a replacement PCV and that brass fitting for the base of the carb?

Thanks so much guys!

 

[middlecalf]

You probably eliminated some vacuum leakage by hooking up a better connection so it will run better for sure. Try spraying some carb cleaner into the PCV valve (remove it first) and shake out any crud. It should rattle if working properly.

One of the Toyota parts gurus can help with the PCV valve replacement. Not sure about the carb fitting - calling all Weber carb gurus!

 

[Tony_Farson]

You probably eliminated some vacuum leakage by hooking up a better connection so it will run better for sure. Try spraying some carb cleaner into the PCV valve (remove it first) and shake out any crud. It should rattle if working properly.

Thanks for the tip on the carb cleaner. Worked like a charm! It is clicking again. The smoother running was short lived though. I have a loud hissing sound coming from the valve cover vent tub now and the pcv line I installed is collapsing from the vacuum pressure. The hissing sound goes away when I open the oil filler cap... I don't get it.

So, I think there's a problem with my Weber carb too. The thing runs rich and I followed a guide on how to tune a/f and idle on a weber, but it makes no sense. My screws we all turned almost to the closed position and setting them according to the instructions makes it run worse. The fumes are so strong they burn my eyes. I also noticed that the electric choke wasn't connected, so I ran a 12V source to it but it isn't working. I also noticed that the linkage is loose and the butterflies aren't opening and closing properly and stay open after release the accelerator leaver. ih8carburetors! I'm going to take it to a VW customizer in town who specializes in Weber and see if he can make sense of things. I think I'm going to put TBI on the 2F I just bought to replace the F I have in it now.

 

[David70FJ40]

Had the same problem with the butterflies not shutting when I released the accelerator pedal. Turned out it was a worn accelerator cable. Installed a new one and the problem disappeared.

 

[65swb45]

Had the same problem with the butterflies not shutting when I released the accelerator pedal. Turned out it was a worn accelerator cable. Installed a new one and the problem disappeared.

This could be related to the running rich problem too.

With regards to the hiss and opening the filler cap, I’d be concerned that something in the PCV system isn’t working properly, even though it’s all hooked up.

 

[Weber Sarge]

The pcv valve's job is to keep a slight vacuum on the engine's crankcase. This helps with oil seals and to keep the rings seated properly. Your first order of business is always a compression check - if there is excessive blow-by from worn rings or other issues no valve is going to fix that. Besides, the valve will not work properly anyway and due to the blow-by pressure it can actually turn the pcv system into a bad vacuum leak on the intake side.

Another thing - rich running conditions are almost always traced back to either excessive fuel pressure or incorrect float settings. If the carb was part of a kit for your Cruiser - it should be jetted very closely to match that engine and it's flow rates/fuel curve requirement. Here's the issue with the Weber - it likes no more than 3psi of fuel pressure and off-road even less. There is no true regulator available today that is reliable and consistent enough to work correctly for a pressure limit of 3psi unless you want to get into bypass systems that cost north of $300 or more. Now, with that said , there are options -

One, and often used is an electric fuel pump versus the stock mechanical. A low pressure cut type pump will shut off at a pre-determined pressure rating. The US made Facet low pressure, Airtex low pressure and a few others are decent candidates. BUT - without a return line you're relying on that pump to work correctly, if it gets any dirt in it and cannot hold the pressure as well as shut off it's solenoid plunger/motor they are notorious for burning out , not to mention good quality ones are getting rare and expensive. Really good quality fuel filters are required ahead of the pump as well as a very clean fuel system.

Two, and probably by far the most simple and reliable - use a bypass line to route excess pressure back to the tank. With this system, you can run either the stock mechanical fuel pump or an electric - doesn't matter. Easiest way, if the truck is equipped with a return line as many are - use a fuel filter for a Jeep CJ series. It has one 5/16" inlet and two outlets - one 5/16" for the carburetor, one 1/4" outlet for the return bypass. Due to the way these are made internally, excess pressure is routed back to the tank and stops the issue of pressure overrun at the carburetor. We've been using this setup for years on various smaller engines that require low pressure fuel systems and especially for Weber carb builds for offroad use. The modified carbs I built were altered to keep the vent from causing problems at extreme angles - my setup would easily run at almost 90*, which no carb is intended to ever handle. The filter will only bleed off the excess pressure, it will flow more than an adequate amount of fuel for the engine without starvation and is a very well-proven mod.

This setup is currently feeding a Kohler K482 twin opposed engine on an old Wheel Horse garden tractor of mine with an electric fuel pump - that engine only wants about 2-3psi maximum, any more than that and the float cannot handle the pressure - very much like your Weber. This setup with an electric pump is self-priming and very reliable - the constant flow of fuel running in a loop works to keep the pump from overheating . Both rotary and pulse types pumps can get very hot and burn out easily - this stops that in it's tracks. If you place one of these filters just past the stock fuel pump and route the bypass into the return line you MUST make certain it goes directly to the tank . Some systems on Cruisers use various vent canisters and fuel vapor separators - if a return line runs through any of those parts you'll introduce solid fuel to a place it doesn't belong - and make a very bad leak. The return line must be solidly routed straight back to the tank and away from the inlet or any smog equipment - so this isn't for every application, only Weber aftermarket carburetors. Almost all Japanese trucks have a return line of some sort - you just need to fully inspect how your vehicle was built and go from there.

I can't find any pics right now but this is a common mod in the off-road network on engines running a Weber carburetor. Many threads out there covering the subject and many of the older ones are mine - just do your research. I do highly suggest a compression check to start with so you know the condition of the engine - no carb can fix a bad engine.

If you want to explore this - need to know how your entire fuel system is currently built. I try to check in once in awhile but I'm not always here but others will chime in that have done the mod.

Sarge

 

[David70FJ40]

I guess this is why I get a whiff of raw fuel once in a while. Great information that I will use.

 

[Dizzy]

Yes, an F motor Weber kit should be correctly jetted, but it does not apply when you are running on thinner air at altitude. If your mix screw is close to all the way in at idle, then, it is safe to say that, you are idling on your primary main jet and the speed screw is probably more than 2 turns in. It is turned in more because a 32/36 Weber can't deliver enough air for idle, without being tricked-out, on motors bigger than 2L according to Pierce Manifolds Youtube video, especially with Reno's thin air.

Do you know how many turns in your speed screw is adjusted to? It might be tight getting between the electric choke and valve cover. Do you know which jets are in the carb?

The electric choke may not have enough pre-load, it is adjusted by turning the spring's external housing after you loosen up the three screws a bit. And a DGEV has a stepped cam for choked-fast-idle--you have to depress the throttle or it will not fully close.

 

[Tony_Farson]

Yes, an F motor Weber kit should be correctly jetted, but it does not apply when you are running on thinner air at altitude. If your mix screw is close to all the way in at idle, then, it is safe to say that, you are idling on your primary main jet and the speed screw is probably more than 2 turns in. It is turned in more because a 32/36 Weber can't deliver enough air for idle, without being tricked-out, on motors bigger than 2L according to Pierce Manifolds Youtube video, especially with Reno's thin air.

Do you know how many turns in your speed screw is adjusted to? It might be tight getting between the electric choke and valve cover. Do you know which jets are in the carb?

The electric choke may not have enough pre-load, it is adjusted by turning the spring's external housing after you loosen up the three screws a bit. And a DGEV has a stepped cam for choked-fast-idle--you have to depress the throttle or it will not fully close.

I am in the process of rebuilding a 78 2F for my 68' and I will be ordering TBI for it rather than messing with a carb. Have I mentioned how much I hate carbs?