64fury

Over the winter I replaced the stock valve covers (which had one pcv valve on the pass side, and a breather cap on the driver side) with the Mopar alloy valve covers and replaced both oil caps with breather caps, I removed the pcv valve that was running to the carb.

Now after running the engine I notice fumes/smoke coming out the oil breather caps, if I replace the breathers with the stock oil caps the engine runs poorly as there is no crankcase venting.

I'm going to install a pcv valve on the pass side and run with the non breather cap on the other, will this work or will both valve covers need to be vented?

The amount of fumes/smoke coming from the breathers now is not excessive but noticible, and if you run with the non breather caps you can hear a suction if you take one off with the engine running, is any of this normal?

This is my first Mopar, big bloack and v8 engine, I've mostly dealt with 4 banggers in the past, so forgive the noobie questions!

440roadrunner

No, you need a breather. as well as PCV The normal way is to use a breather with a fairly large hose, and connect to the air cleaner. On my aftermarket valve covers, which had no baffles inside, I used to use !!!Ford!!! breather/ caps. You used to be able to buy Ford filler cap/breathers in chrome, fit around 68??--70?? Mustang and others, as well as having a grommet in the top, which would fit (some) PCV valves, as well as an elbow for the air cleaner hose.

If you don't want to use an open hose to the air cleaner, at least use a big vented breather.

I would be willing to bet that if you don't hook up the air cleaner hose, you will still get some oil vapor and fumes, possibly into the pass compartment, under high RPM, wide open throttle. This is because that is when the engine makes the most blowby, and has the least amount of PCV action. That is one reason why the stockers go to the air cleaner--this blowby can then be sucked into the carb instead of being dumped overboard.

64fury

Thanks!

So if I route the pass side pcv valve to the port on the side of the carb, and run a breather line from the drivers side valve cover to the port on the air cleaner I should be ok? Or would it be best to run both to the air cleaner and plug off the port on the carb?

440roadrunner

I would definately keep a PCV valve.

the older cars, before PCV, used to have what is called a "road draft tube" that went down under the car to generate a little bit of vacuum, and cause a "draft" through the engine. What was supposed to happen is clean air should enter the breather up top, go down with the fumes through the engine, and exit out the draft tube.

Older engines with lots of blowby would still expell fumes out the top breather, and these would find their way into the pass compartment---smell.

Make sure your PCV is connected to the proper port--a large "full vacuum" 3/8 fitting on the carb or manifold, usually on the carb.

Does your engine use a lot of oil, or pretty good shape?

64fury

Not Sure, I haven't had it on the road yet, bought just before the snow came down, never got to drive it. It was sitting for 7 years. Does not burn oil, although she is running rich and the gas in the tank has been sitting for 7 years so it's crap. Just trying to get the plumbing sorted out before spring!

It has a single 3/8 inlet on the rear of the carb, eddelbrock, there is a vacuum outlet on the front going to the dizzy and a vacuum outlet on the manifold for the heater cotroles etc! The only other place to plumb in the breather would be the air filter assm'y

All the other cars I've delt with have had the crankcase vents going to a carbon canister.

64fury

440roadrunner.

What did you have in mind when you asked about the engine using lots of oil??

I have one valve cover with a breather to allow air in and the other with a pcv valve to allow pressure out, but there always seams to be smoke coming from the breather!

This has me wondering if I don't have a issue with a valve guide or the piston rings?

440roadrunner

That's why I asked, but oil blowby can be somewhat subjective. Especially with these cars, people typically drive them infrequently, so they can use oil some 'til they get "cleaned out." However, running an open breather--as opposed to one plumbed into the air cleaner, will make things worse, and may smell in the pass. compartment.

If the pcv valve is old, I'd replace it, and inspect the hose. It may be partly plugged, and also make sure it's hooke to a good free flow port on the carb/intake, so it's not all carboned/gummed up.

I actually looked for a picture on the 'www for the type of camp I used to use. It was off a '70's HP Ford, had the bayonet twist in style, and a grommet in the top, you could actually use two, and hook the pcv to one, and the air cleaner to the other.

One thing you may be missing here, is that stock valve covers had fairly large baffles inside them to prevent oil splash, which can make blowby worse.

64fury

The PCV I have now, is the new plastic one for the later models not the metal one for the pre 65's, but the Early one won't fit on the mpoar alloy covers. Anyways the PCV valve is hooked to the air filterbox, not to the vacuum port on the car, I'm thinking if I move it to the port on the carb the vacum will draw more of the fumes out of the system. And instead of using an open breather run a closed breather to the now open spot on the air cleaner. or is my thinking *** backwards?

Would using a thicker oil be helpfull?

440roadrunner

I misunderstood, somehow. Yes, you MUST have the pcv valve hooked to vacuum!! Otherwise, the pcv does nothing!!

If you hook up the PCV to vacuum, you might just find that now you can get away with an open breather on the other side. However, as I said earlier, I recommend (always) that you hook the breather to the filter box--just as it is on modern cars. Again, this is to "encourage" any extra blowby coming out of the engine to be drawn into the carb.

The main reason for this is to prevent smell in the passenger compartment, and to keep oil residue from forming on various places in the "engine room"

64fury

Ahhh! Gotcha, Thanks for the help so far btw!

What was confussing me was the car came with the glovebox owners manual, and it had a diagram of the crankcase vent set up, with an open breather on the drivers side, and the PCV valve on the pass side routed to the air box.

I'll hook it up to the vacuum port and run her this afternoon and let you know!

67 GTX

[quote=krislou80;52222]
The common way to check the PCV valve is to take it out and shake it. If it has a rattle then it is supposed to be good, no rattle it is assumed to be plugged up and no longer working. I am not certain if that is still a valid check.

thats the way I do it