Indycars
Well-Known Member
I used an AC Delco PN: CV-746-C that fits the 68-69 Z28 Camaro application.
Figured that was as close to my situation as an OEM valve would get. It's installed
in one valve cover and a breather in the other valve cover. So far I have no oil build
up in either place, not sure if that's good or bad. The engine has 4000 miles.
If you want to go really high tech then there is a dual flow and adjustable PCV valve,
but it's expensive at $129. Lot of theory on their website also.
M/E Wagner Performance Products | High Performance Crankcase Ventilation Systems
Figured that was as close to my situation as an OEM valve would get. It's installed
in one valve cover and a breather in the other valve cover. So far I have no oil build
up in either place, not sure if that's good or bad. The engine has 4000 miles.
If you want to go really high tech then there is a dual flow and adjustable PCV valve,
but it's expensive at $129. Lot of theory on their website also.
M/E Wagner Performance Products | High Performance Crankcase Ventilation Systems
ChrisK
Member
Back in my Mustang days we used to vent one side then run an oil seperater on the other. The oil seperator was a glass bowl type used on air systems. Mine was made by Campbell Hausfield.
My current engine has dual breathers and no vacuum system so I might do the seperater thing on there.
My current engine has dual breathers and no vacuum system so I might do the seperater thing on there.
fletcherson
Well-Known Member
Ive done dual valve cover vents plumbed into the headers, that keeps anything from contaminating the fuel via engine vacuum, the exhaust creates its own vacuum. Not particularly emissions compliant, lol... There are kits at the speed shops. I used quality vented breathers with pcv valves also to help prevent pulling the oil out. The kits use valves similar to smog pump air valves. The big thing I've found is most aftermarket valve covers have no or inadequate baffles, so the oil is slung all over and expelled or vacuumed out of the breather. I made baffles for the inside of them and it really helped reduce oil consumption via the vents.
fletcherson
Well-Known Member
Yea, I imagine he has a bit more crank case pressure to deal with. What's he doing now? Is there an issue he's contending with?
No problem, but after many attempts I've found a good arrangement that I will reveal soon (I do like suspense). Indycar's link has excellent info re PCV valves and why the aftermarket ones may not work for you.
The blower doesn't make any significant difference since 99% of the time there is no boost and no increased blowby.
old round fart
Well-Known Member
When I had my car it ran around on 0 boost until I matted it then it pegged a 10 lb gauge. Then it got fun!
I started with hoses from each valve cover down to the ground, what used to be called “road draft tubes.” This relieved crankcase pressure, but the bottom of the car got oily. Then tried a breather on each valve cover, but the engine and firewall got oily. Tried a fancy aftermarket PCV valve on one side and a breather on the other, but it didn’t seem to work; still got oil on the motor and firewall. PCV valves are supposed to be closed at high vacuum, like idle, so as to not affect AFR and idle quality. Then they open at cruise. But my motor has high vacuum all the time, 20” at idle and in the teens at cruise, and I suspect the PCV valve never opened, forcing the fumes out the breather. Couldn’t find specs on the valve. Apparently OEM PCV valves are matched to the motor they are on, so the aftermarket ones may or may not work for you. Now some cars, particularly in Europe, use a “calibrated orifice” (i.e., a small hole) instead of a PCV valve. This orifice simply draws fumes from the crankcase at all times. Long story short, here’s what I use now:
There are what appear to be breathers on each valve cover, but they are fakes. The right one has an orifice (a disc with a 1/16” hole) and a hose to the intake manifold. The left one simply has a hose to the air filter housing. In normal operation the motor sucks the crankcase fumes through the orifice and clean air enters through the air filter. If the crankcase pressure should exceed the capacity of the orifice then fumes would back up into the air filter and be drawn into the intake for reburning. I used clear hoses for awhile to monitor the operation. I saw that fumes were being drawn into the intake and noticed some water condensation would appear in the air filter hose occasionally, possibly due to low ambient air temp. I check the spark plugs frequently and they look fine; no oil or carbon. So this system seems to work. The motor and car stay clean, I’m doing my part to control emissions and no PCV valve to clean or replace.
More reading: Positive Crankcase Ventilation: theory of operation, plus
There are what appear to be breathers on each valve cover, but they are fakes. The right one has an orifice (a disc with a 1/16” hole) and a hose to the intake manifold. The left one simply has a hose to the air filter housing. In normal operation the motor sucks the crankcase fumes through the orifice and clean air enters through the air filter. If the crankcase pressure should exceed the capacity of the orifice then fumes would back up into the air filter and be drawn into the intake for reburning. I used clear hoses for awhile to monitor the operation. I saw that fumes were being drawn into the intake and noticed some water condensation would appear in the air filter hose occasionally, possibly due to low ambient air temp. I check the spark plugs frequently and they look fine; no oil or carbon. So this system seems to work. The motor and car stay clean, I’m doing my part to control emissions and no PCV valve to clean or replace.
More reading: Positive Crankcase Ventilation: theory of operation, plus
Yes, the hose goes to the bottom plate of the filter housing, so it always gets clean air.
Screaming Metal
Active Member
Well, on the blown motors, venting the crankcase hase always been a fun agenda....theres lots of ways to do it. Pressure gets past the rings to a certain extent....
Chevy did a bang up job with the pcv system on their hi-perf motors back in the 70's....I just connect to the airclears. Don't use the baseplates on the carbs unless your running the nice spring loaded ball pcv valves....as a backfire could contaminate your oil supply....not to mention wreak havok on your gaskets....
Chevy did a bang up job with the pcv system on their hi-perf motors back in the 70's....I just connect to the airclears. Don't use the baseplates on the carbs unless your running the nice spring loaded ball pcv valves....as a backfire could contaminate your oil supply....not to mention wreak havok on your gaskets....
tbucketlar1
Member
I have been trying to see how to post a questions on this forum. It will not let me I push contact us no answer I keep different things but no luck. That is why I put it here. Getting frustrated about ready to bale
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