My 427 SOHC Build..... Finally the time has come!

[jayb]

If the holes in those metal caps are really small, kind of like a couple of punch outs, that could be a problem.  Some "breathers" don't really breathe all that well...

[cobracammer]

yea its the metal cap with a couple of holes "Punched" into the under side.  I will pick up some others that are filter filament all around.  Also I will give each of the oil pan studs a little snugging up.  Hopefully between those items and the new manual steering rack, it will stop the "drippings"  lol

[My427stang]

Ever consider a PCV?

[cobracammer]

Hey Ross,

After your post, I was trying to look into this.  Is it literally just a valve that fits into the valve cover (to vent crank case gas) and then a hose runs to the intake manifold (to re-cycle the scavenged gas)?  Definitely possible (maybe a PCV valve on one valve cover and a breather on the other)?

Looks like these are usually used in conjunction with an oil separator?  thoughts?  It looks like you get just pick up a PCV valve at the local auto parts store, but then one of the breather tubes will need to be pulled out and a rubber grommet installed so the PCV valve pops in?

I wonder about the effect on manifold vacuum (since the PCV valve plugs into the intake manifold) and how that will affect the EFI computer (as it works based off of vacuum)?

Good Suggestion  :0)

[cobracammer]

OK so I found some PCV valves that are push in (and actually match the same stype of the oil filler tubes/ breather cap's I have on there now.  I found one that's a Push in PCV valve that will fit the hole of the tall oil filler tubes on the Cammer valve covers.  I think that the oil filler tubes are pretty tall, and thus not much if any oil will get sucked out? (Not really sure).  Possibly there wont be a need for an oil catch can?

Also, would 1 PCV valve feeding into a vacuum port on the throttle body be enough to stop the crankcase pressure from building?  I guess I am looking at the size of the PCV valves and wasn't sure if it can keep up with the pressure (or possibly I need 2 PCV valves (both push on) and I can install one in each tall oil filler tube.......  then I can T them into the larger vacuum port on the throttle body?

Thoughts?

[WConley]

You generally want one PCV valve pulling from one rocker cover, with fresh make-up air entering from the other rocker cover.  There needs to be some type of baffle under the PCV valve to keep it from sucking oil. 

Pulling fresh air through the engine will keep your oil a lot cleaner!  It's worth it if you can calibrate the EFI to work.  (It may be as simple as adjusting the plate on that one throttle body a bit...)  The oil baffle may be the hardest part of it though.

- Bill

[My427stang]

You generally want one PCV valve pulling from one rocker cover, with fresh make-up air entering from the other rocker cover.  There needs to be some type of baffle under the PCV valve to keep it from sucking oil. 

Pulling fresh air through the engine will keep your oil a lot cleaner!  It's worth it if you can calibrate the EFI to work.  (It may be as simple as adjusting the plate on that one throttle body a bit...)  The oil baffle may be the hardest part of it though.

- Bill

Concur completely, and I cannot imagine it will even make a significant difference in the tune. However, it will pull moisture that causes acids out of the oil.  Needs to be baffled though.

[machoneman]

OK so I found some PCV valves that are push in (and actually match the same stype of the oil filler tubes/ breather cap's I have on there now.  I found one that's a Push in PCV valve that will fit the hole of the tall oil filler tubes on the Cammer valve covers.  I think that the oil filler tubes are pretty tall, and thus not much if any oil will get sucked out? (Not really sure).  Possibly there wont be a need for an oil catch can?

Also, would 1 PCV valve feeding into a vacuum port on the throttle body be enough to stop the crankcase pressure from building?  I guess I am looking at the size of the PCV valves and wasn't sure if it can keep up with the pressure (or possibly I need 2 PCV valves (both push on) and I can install one in each tall oil filler tube.......  then I can T them into the larger vacuum port on the throttle body?

Get a '69-'70 Boss 302 PCV valve as it's rated as one of the lowest flow pieces around.

https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#tbs=vw:l,mr:1,price:1,ppr_max:25&tbm=shop&q=boss+302+PCV+valve

A big no to two valves: As previously noted, only one PCV valve in one breather. The other breather is the fresh air source.

All PCV valves are rated but few are stamped as such and even more oddly, getting a hold of the actual ratings is damn near impossible. Keep in mind one can also limit the flow later if need be buy sticking a short chunk of aluminum rod stock in the rubber hose after drilling say a .090 or .080 hole in the rod stock. 

If those tall breathers have a deflector plate at the bottom (i.e. valvetrain side) you can stick some SS scubber pad material (yes, it's called Choreboy, the stuff one uses by the kitchen sink) down the tube to act as a mist screen. It does work, just don't stick in too much. True SS steel wool works too but DO NOT use regular steel wool as it does rust due to condensation!

[My427stang]

To be honest with you guys, I never even look at PCV flow.  I go to the local parts store, grab the first I see with a 3/8 90 degree end and slip it in the baffled valve cover

Haven't had a carb tuning issue, and EFI certainly can compensate.  Not saying there aren't times that it could be fussy, otherwise there wouldn't be so many options, but I just haven't seen it in my street builds.

[cobracammer]

Hey Guys,

I have seen that some people will thread a hose barb into the air cleaner and just have the crankcase vent through the PCV valve into the air cleaner (above the throttle bodies).  Is this possible?  or do you need to be plumbed up directly to a vacuum port on the throttle body (Carb)?  I think if there was even the slightest chance of the EFI not liking the PCV , letting it vent into the air cleaner would be a good option.  Not sure how much vacuum is needed for the PCV as well as how much vacuum is inside the air cleaner  LOL

[WConley]

The PCV must have full manifold vacuum to work.  Plumbing a line just to the air cleaner is no different from the plain breather cap you have now.

The vacuum forcibly draws out the crankcase blowby gases, and pulls in fresh air from the opposite side of the engine. 

I don't see the PCV being much different from the brake booster, as far as EFI tuning goes.  I agree with Ross that it should be no big deal.  The benefits make it so worthwhile.  I have used PCV on all of my stuff.

[cobracammer]

Awesome.  I am going to measure the diameter of the breather tubes when I get home and order the set ( breather and PVC)from Jegs.

[My427stang]

Let me add to that

In what I call a "semi-closed" system, you would have

1- A PCV connected to a full time (manifold) vacuum source that would evacuate during idle and part throttle
2- A second tube, usually a filtered breather tube that is an air source at light throttle, and when vacuum is at zero, could relieve pressure into the air cleaner

For normal street/hot rod systems you have #1, but number 2 is just an open breather.

Keep in mind, the "semi-closed" system really is a benefit for emissions as any blowby, in any case, gets reintroduced into the system.

[cobracammer]

Thanks Ross,

I guess one last question (since it seems like its the best solution)....  Given the type of engine this is, and the fact it has (I believe) 12:1 Compression on 93 octane, I was reading a little online (Yeah I know... Dangerous) and there was concern that PCV valves feeding blow-by gasses back into the intake to be re-burnt can cause detonation on high compression engines.  Is this valid?  Just curious  :0)  I tried looking for pictures of other Cammer engines to see if they used a PCV valve anywhere, but could not find any.  The only thing you come across sometimes is the vacuum pump (like on Jays drag car).  Most of the others have between 2 and 3 breather tubes with the "old -timey" breather caps on them like I have.  lol  Never put into production cars, so I guess it was never a thought.

[jayb]

Thanks Ross,

I guess one last question (since it seems like its the best solution)....  Given the type of engine this is, and the fact it has (I believe) 12:1 Compression on 93 octane, I was reading a little online (Yeah I know... Dangerous) and there was concern that PCV valves feeding blow-by gasses back into the intake to be re-burnt can cause detonation on high compression engines.  Is this valid?  Just curious  :0) 

That is indeed a valid concern, and that is why I never run a PCV valve; I have had that exact experience.  But for the cost, I'd give one a try and see if its workable on your engine.  You can always pull it back off - Jay