Opinion on PCV valve for flathead?

[scooder]

Try plumbing in a air/fuel ratio gauge and see what happens when you add a pcv.
Pcv's are a vacuum leak however you look at them, modern stuff's computer's deal with it fine, it's a bit of a job trying to get a carburettor to deal with it.
Obviously the oily air gets burnt in the combustion process, but it still lowers the resistance to detination (sp?) as does the vacuum leak. This ain't really a concern on a naturally aspirated engine, but bring a supercharger to the party and the needs change. The importance of clean air and good gas goes up massively.
All that being said, with a supercharged engine why make it more prone to detination? A step in the wrong direction I feel.
You can imagine what you want.
Martin.

 

[51 MERC-CT]

Try plumbing in a air/fuel ratio gauge and see what happens when you add a pcv.
Pcv's are a vacuum leak however you look at them, modern stuff's computer's deal with it fine, it's a bit of a job trying to get a carburettor to deal with it.
Obviously the oily air gets burnt in the combustion process, but it still lowers the resistance to detination (sp?) as does the vacuum leak. This ain't really a concern on a naturally aspirated engine, but bring a supercharger to the party and the needs change. The importance of clean air and good gas goes up massively.
All that being said, with a supercharged engine why make it more prone to detination? A step in the wrong direction I feel.
You can imagine what you want.
Martin.

I have had an AF gauge installed for some time and there is not any detectable difference when the PCV vacuum is disconnected. (no imagination or speculation)

 

[scooder]

That's contrary to what I have found. On a wide band gauge setup and on a workshop exhaust sniffer, the difference was notable, hence my post.
And again, we're talking a supercharged engine here. The fuel mixture is critical so why throw in a variable that ers on the side of lean?
I'd vent to atmosphere, with a catch can. Simple and absolutely won't screw with the fuel curve or effect the rest of the engine in any negative way.
Sure makes sense to me.
Martin.

 

[Ronnieroadster]

Just wonder how millions of vehicles use PCV systems without any vacuum related issues and the "oil fume laden air" gets burnt up in the combustion process as the system was designed to do, also without any issues either real or imagined.

Thats exactly correct and it has no ill effects to any supercharged application also proven by many thousands of miles doing just that with my supercharged vintage Flathead and ARDUN converted engines.
Ronnieroadster

 

[jrvariel48]

Try plumbing in a air/fuel ratio gauge and see what happens when you add a pcv.
Pcv's are a vacuum leak however you look at them, modern stuff's computer's deal with it fine, it's a bit of a job trying to get a carburettor to deal with it.
Obviously the oily air gets burnt in the combustion process, but it still lowers the resistance to detination (sp?) as does the vacuum leak. This ain't really a concern on a naturally aspirated engine, but bring a supercharger to the party and the needs change. The importance of clean air and good gas goes up massively.
All that being said, with a supercharged engine why make it more prone to detination? A step in the wrong direction I feel.
You can imagine what you want.
Martin.

Scooder, I have a wide band air/fuel gauge so I can certainly see if there is a difference if and when I install the pcv. Thanks for your info!

 

[jrvariel48]

Scooder- "I'd vent to atmosphere, with a catch can. Simple and absolutely won't screw with the fuel curve or effect the rest of the engine in any negative way.
Sure makes sense to me".
Martin.

Can you elaborate on the catch can set up? Is the pcv still used?
Thanks

 

[jrvariel48]

I have had an AF gauge installed for some time and there is not any detectable difference when the PCV vacuum is disconnected. (no imagination or speculation)

Merc, what set up do you have? Are you running a blower? Tell me what ya got!
Thank you, Joe

 

[jrvariel48]

Thats exactly correct and it has no ill effects to any supercharged application also proven by many thousands of miles doing just that with my supercharged vintage Flathead and ARDUN converted engines.
Ronnieroadster

Ronnie, Thanks for your reply! I'm glad to hear about the amount of care free miles you logged with this set up!
Thanks!

 

[Phil Gillespie]

I have had an AF gauge installed for some time and there is not any detectable difference when the PCV vacuum is disconnected. (no imagination or speculation)

Where exactly is the AF gauge sensor installed? As i understand the location of the sensor is important to correct readings.
Phil NZ

 

[51 MERC-CT]

Where exactly is the AF gauge sensor installed? As i understand the location of the sensor is important to correct readings.
Phil NZ

Most gauge manufactures provide their recommendation as to where it should be located.
Mine is located about 4 inches behind the left Fenton exhaust flange and in an upper most quadrant of the exhaust pipe.

 

[jrvariel48]

Mine's a little further down the exhaust as per the manufacturer. I've been reading up on the catch cans and I don't see how it could hurt to have one. It seems like what I'm hearing as compared to what I'm reading about these things, is that it's beneficial especially with a supercharger. It will remove most of the heavy crap from the air going through it. Thoughts??

 

[jrvariel48]

Can anyone comment any further on a catch can and PCV set up?

 

[Ronnieroadster]

Can anyone comment any further on a catch can and PCV set up?

Dont have a clue as to what a catch can would accomplish. Its certainly no substitute to what a PCV valve is doing.
However A catch can is used when a vacuum pump is added to the crankcase in that capacity the catch can separates the water vapor from the oil. This type of system would only be used in an all out racing application. The one drawback to using a vacuum pump is theres a possibility if the draw is to high oil can be drawn from vital areas such as the piston wrist pins.
Ronnieroadster

 

[jrvariel48]

Ronnie, I was looking at it in a different way. This would be used in conjunction with the PCV, being mounted in between the PCV and the vacuum source.
Here's what I've read:

Separates oil particles from PCV/CCV air using 50 micron bronze filter
100% billet 6061 aluminum sealed can
Defends intercooler, intake system, and essential components from oil blow-by
Helps maintain proper octane levels to reduce potential detonation

I was looking at it as sort of an air cleaner before it's returned to the motor
Thanks, Joe

 

[Ronnieroadster]

Ronnie, I was looking at it in a different way. This would be used in conjunction with the PCV, being mounted in between the PCV and the vacuum source.
Here's what I've read:

Separates oil particles from PCV/CCV air using 50 micron bronze filter
100% billet 6061 aluminum sealed can
Defends intercooler, intake system, and essential components from oil blow-by
Helps maintain proper octane levels to reduce potential detonation

I was looking at it as sort of an air cleaner before it's returned to the motor
Thanks, Joe

Thats an interesting addition to the PCV system but I see no gain in using it in our vintage engine applications. Heck even the high end performance stuff i have on occasion to be involved with have never used anything like that. However from what you wrote theres no ill effects from using it so if you want to add it to the system go for it just remember it needs to be emptied from time to time if any oil /water ends up in the container.
Ronnieroadster

 

[jrvariel48]

Thats an interesting addition to the PCV system but I see no gain in using it in our vintage engine applications. Heck even the high end performance stuff i have on occasion to be involved with have never used anything like that. However from what you wrote theres no ill effects from using it so if you want to add it to the system go for it just remember it needs to be emptied from time to time if any oil /water ends up in the container.
Ronnieroadster

Thanks for the input Ronnie!

 

[jrvariel48]

Update on the pcv install. I found a dual circuit pcv valve made by Wagner so you can adjust your idle and cruise vacuum requirements separately as well as how much vacuum you're pulling through the pcv. At idle, I'm at 2 inches and cruise about 7 inches. I ran the return back to the carb through a catch can set-up that has a 50 micron bronze filter to help clean up the air a bit and remove moisture or oil before it's reintroduced into the motor. I also installed a K&N breather cap and blocked of the oil pan vent. I just went for a test run and I din't notice any changes as far as air/fuel ratio's.
I did notice that when I'm stopped at a light there's no more smoke!! This is a plus and the main reason I installed this set-up. I know some of you will say it's too expensive and unnecessary, but with the supercharger and detonation being a potential problem, I wanted to be able to adjust the system accordingly. It's a small price to pay compared to a burnt up motor.

 

[19Fordy]

I don't run a PCV on my 8BA. Tried one and found car ran better without it.

 

[49Ragtop]

My 63 Cadillac I used to own pulled the crankcase gases right up to the Carburetor using a PCV valve and used a ventilated oil filler cap. I never had any problem with it except you had to keep the PCV valve clean and it was mounted horizontally. I going to do the same with my flathead. only 10 years late than your posts.

 

[britman]

I am running an 8BA w/ an early Eddie Meyer intake. I capped off the road draft tube w/ an elbow fitting and then drilled a hole into the center runners of the intake and installed a threaded PCV valve. It really cut down on the blow by, and it is hidden.

I have a system similar to this set up. After a few thousand miles I have had no problems and I have no blow by inside the car--I don't miss it!