positive crankcase ventilation

[Schreiber]

I would like to cut down on the fumes coming into the Bronco. A friend pointed out a quick fix this weekend - reroute my pcv setup. I currently have a stock? two-barrel holley carb, aftermarket air filter (without nipple), a lonely PCV elbow on my passenger side valve cover, and my driver side routed to the nipple on the back of the carb. Would I better to route my passenger side elbow to the nipple on the back of the carb and stick a standard oil cap on my driver side valve cover? Am I gonna need replacement seals if I start switching things? Would this help with the smell of fumes coming into the cab? Just thought I would test the waters before makes changes.

 

[broncnaz]

It wont change a thing rerouting it. At most you would probably get a messy valve cover from oil that would leak out of the breather. If your getting fumes in the cab then you need to seal the firewall better. If its fumes into the carb your worried about then all I can say is dont worry thats how the system is designed.

 

[Pokey71]

It wont change a thing rerouting it. At most you would probably get a messy valve cover from oil that would leak out of the breather. If your getting fumes in the cab then you need to seal the firewall better. If its fumes into the carb your worried about then all I can say is dont worry thats how the system is designed.

If he has a PCV on one side then there "should" be no blow by.

I did and would recomend a PCV on the pass side going to the carb and the drivers side should have the filter on it. Thats how I ran mine

 

[Viperwolf1]

Put a hose on that passenger side nipple and run it through the bottom of the air cleaner. That way it'll suck any excess blowby gasses into the cylinders and burn them like it's supposed to.

 

[bronko69er]

Are we all sure that he is not smelling exhaust fumes?
Do you have any exhaust leaks?
Where is your tail pipe exiting?
What sort of top configuration are you running?

 

[broncnaz]

If he has a PCV on one side then there "should" be no blow by.

I did and would recomend a PCV on the pass side going to the carb and the drivers side should have the filter on it. Thats how I ran mine

The key word is should. But the way the PCV valve works you can still get blow by build up and it is very common for valve cover mounted breathers to fill up with oil and cause a mess. It could also just mean the engine is worn and just has to much blow by for the PCV system to handle.

 

[00gyrhed]

MAybe Im an idiot but the way you are arranged you will be drawing dust into the passenger side valve cover all the time. Thats why that hose is supposed to go to the air filter. If you run it that way in my neck of the woods lond the top of that cylinder head will be full of dirt in no time.

 

[broncnaz]

I didnt even really look at the pictures. You aftermarket aircleaner should have had a adpater similar to this. http://www.summitracing.com/parts/MRG-2079/
Although they are usually not installed but there is usually a spot on the base of the aircleaner that you punch out and then install the adpater then you just hook a hose from it to the valve cover.
It makes no differance which side the PCV valve is on but you do need some type of breather on the open side. Most broncos I've seen always had the PCV valve on the drivers side oil fill cap.

 

[Schreiber]

This thread has been dormant for a few months, so I'm raising it from the dead. Show me pics of your PCV setups, and make recommendations on suppliers/parts you like. I think I've figured out the way it SHOULD be, but I would like to see some pics to compare.

 

[broncnaz]

Here's a pic of my setup which is basically the same as yours. With a 10 in air cleaner and a holley 4V carb the hose on pass side fit perfectly I would think that with a 2V carb you should also have plently of clearance.

Some people just install small filters on the pass side valve cover such as these. http://www.summitracing.com/search/...-Attachment/Push-in/PCV-Valve/No/?Ns=Rank|Asc
but I personally dont care for most of these types as most will endup filling with oil and making a mess of your valve covers. they work good on fresh engines but once you get some wear you will have messy valve covers.

 

[Steve83]

This caption explains how the system works, and how to fix it right:



But the PCV system will have NO effect on exhaust fumes coming into the cab.

 

[76 bronco J]

>>>> for my carbed motor... I run with the PCV on the passenger side & 5/8" hose on the drivers side connected to a remote breather...this way keeps air cleaners & valve covers clean... cons>>emission police don't like this method ......

 

[lil red]

When I bought mine, the Pcv vavle was on the passenger side plumbed to a spacer plate under the carb. The driver side had a breather installed. Now that the motor has been rebuilt, I put a new breather on the drivers side and plumbed the Pcv valve into a fitting that I installed on my new intake just behind the carb.

Is that right or should I route it up to the adapter that came with my new air cleaner?

 

[Steve83]

Hard to say from a text description, but the PCV valve doesn't go in the intake. Post pics of your setup.

 

[lil red]

Here it is, before and now

 

[Steve83]

The NOW pics are backlit & blurry, so I can't tell how the PCV valve hose is connected, or where the intake is. Is that a filtered oil filler cap?

 

[lil red]

Steve,

Look in the first now pic. If you can zoom in behind the carb, you will see a blue fitting that I installed. The hose is not connected right now but sitting right next to it. Yes, the oil filler cap is filtered.

 

[slackccs]

When I bought mine, the Pcv vavle was on the passenger side plumbed to a spacer plate under the carb. The driver side had a breather installed. Now that the motor has been rebuilt, I put a new breather on the drivers side and plumbed the Pcv valve into a fitting that I installed on my new intake just behind the carb.

Is that right or should I route it up to the adapter that came with my new air cleaner?

Since the PCV valve does not completely seal to the valve cover, plumbing the PCV valve to any part of the carb/intake system can effectively create a vacuum leak. On mine, I have a vented oil filler cap on the driver’s side and I run the PCV valve to the fitting on the underside of the air filter. This insures that there is enough vacuum to run the power brakes.

This being said, the “original” configuration in 1969 was to have the PCV valve connected to a fitting installed in spacer between the carb and the intake manifold and the oil filler cap connected to the fitting on the air cleaner (see pic).

Keep in mind that this configuration was just the start of the emission control junk and not necessarily the best configuration for performance.

 

[Steve83]

If you can zoom in behind the carb, you will see a blue fitting that I installed. ... Yes, the oil filler cap is filtered.

So fresh air is filtered in thru the cap, flows down thru the crankcase & back up the R side to the PCV, where it's metered out to the intake. Perfect. ;D

Since the PCV valve does not completely seal to the valve cover, plumbing the PCV valve to any part of the carb/intake system can effectively create a vacuum leak.

The PCV is a vacuum "leak" no matter what, but the lack of a seal between the valve & valve cover has no effect on how much air leaks in; only on the amount of dirt, and the flow rate thru the crankcase. A leak between the HOSE & valve would increase the vacuum leak. But you'd only get a leak between the valve & cover if you have a crappy grommet, and I doubt that's true of the truck in question.

 

[Schreiber]

This is straight out of my Chilton manual. Drivers side goes to air cleaner, passenger side goes to spacer plate... I guess this is the true factory-original way the PCV is set up?