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EFI and PCV - Do they Both Work at the same Factory??
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Author:  Greg Ondayko [ Wed Jul 23, 2008 8:01 pm ]
Post subject:  EFI and PCV - Do they Both Work at the same Factory??
Well After Driving my car around a bit a working out the tuning in Megatune I have a pressure build up in my crankcase..

I have the PCV Valve plumbed to the intake manifold and I dont Yet have the old Breather Hooked to anything.

The Breather used to be hooked to the Air Filter On the Carb Setup.. I just have a Rag zip tied ove the end of the breather until I Build the air Box For the New Air filter..

Well Should I keep the PCV or Just take it out and put Vacum into the Top of the valve cover??

GReg
Author:  Joshie225 [ Wed Jul 23, 2008 8:15 pm ]
Post subject: 
The PCV valve meters the crankcase vapors into the engine. The breather allows air to flow into the crankcase to prevent crankcase vacuum. My '67 has an open breather; later cars vented the breather to the air cleaner so excess blow-by that the PCV valve can't handle would also be burned in the engine. Gotta have the PCV valve connected to a source of vacuum in the manifold plenum or a throttle body port open to the manifold plenum. You don't want the PCV in just one runner as you can get a lean misfire or worse on that one cylinder. All the cylinders need to share. You don't need a rag over the breather as the breather itself is a filter.

Should I go into why you don't want manifold vacuum in the crankcase? I'll throw out one reason: Reduces valve guide lubrication.
Author:  Pierre [ Wed Jul 23, 2008 8:16 pm ]
Post subject: 
Either your rag isn't letting enough air past it or the pcv is clogged.

I left my stock breather open - I thought it had a steel wool filter in it anyways.

PCV acts as a restriction - you'll have to replace the pcv with some other form of restriction (smaller hose?) or else it would act as a vacuum leak.
Author:  Sam Powell [ Wed Jul 23, 2008 8:57 pm ]
Post subject: 
Quote:

Should I go into why you don't want manifold vacuum in the crankcase? I'll throw out one reason: Reduces valve guide lubrication.
Explain that a little more. Why is that? How about race engines that have a vacuum pump on them. Are they restricting valve guide oiling in some way?

Sam
Author:  Greg Ondayko [ Thu Jul 24, 2008 5:15 am ]
Post subject: 
Alright _ i'll check the PCV - It should be Fine as it was Working with the carb Before.. The rag might be too Restrictive..

And the PCV Hose is plumbed into the Bottom Common area of the manifold.. Not into a single runner.

Thanks, Greg
Author:  SlantSixDan [ Sat Jul 26, 2008 6:51 pm ]
Post subject: 
Quote:
Quote:

Should I go into why you don't want manifold vacuum in the crankcase? I'll throw out one reason: Reduces valve guide lubrication.
Explain that a little more. Why is that?
Mmm...yeah. Good question. Offhand it doesn't make sense to me. In the first place, if the valve guides are sloppy enough that oiling is a question of a tug o' war between port absolute pressure and crankcase absolute pressure, then they need refurbished anyhow. In the second place, the absolute pressure differential across the exhaust guide is always going to be against the flow of oil down the guide due to the high positive exhaust pressure, regardless of pressure (positive, negative, neutral) in the crankcase, and we don't generally see lubrication problems with the exhaust guides.

That's not to say that manifold vacuum in the crankcase would necessarily be a good thing. It'd tend to make problems with stock gaskets and seals (floppy portions of the oil pan gasket, valve cover gasket, timing cover gasket, etc. would tend to get sucked in and create vacuum and oil leaks).
Author:  Greg Ondayko [ Sat Jul 26, 2008 7:31 pm ]
Post subject: 
Well I think I have my Crankcase Problem Taken Care of - PCV was sluggish and I Got A new Breather So that Problem is Solved.

I still Have some issues with The Tank Vent... If I use the Charcoal Can it Builds pressure in the Tank.. If I pull A vacum Right on the Vent line of the tank (which runs to the engine compartment and used to connect to the can) It pulls a vacum on the tank so that When I open the cap there is a woosh into the tank.

Should I try another Charcoal can and hook it all up and see if I can get more Vacum to pull through it??

Greg
Author:  Greg Ondayko [ Mon Jul 28, 2008 9:55 pm ]
Post subject:  Tank Vent Problem Solved
The Vent Problem Was most likley caused by Me originally running the Factory original Vaopr line as a return line.. Not all of the gas was out of there when I Tried to convert it back to a vapor line -- So the vapors built up in the tank and went woosh Every time I opened the cap.. So now I have the Charcoal can back in place And the Vacum line is hooked to it and it seems to work fine! Now just more tuning in the VE Bins as I have the Dash AFR Gauge hooked up..

Greg
Author:  Greg Ondayko [ Mon Mar 30, 2009 8:14 pm ]
Post subject:  NEW Issue with this EFI Vent / PCV Setup
So for the last 2 oil changes My oil has been Really Dirty - Basically since I have switchewd to EFI and got the Charcoal can etc. connected up to the intake correctly.


I do have The PCV line and the Charcoal can Vacuum line connected to one Single port on the intake VIA a T - Less fittings and drilling that way.

I think the Vacuum is somehow pulling charcoal out of the can and into the oil?? anyway, Can just bypass the Charcoal Can and Just pull a vacuum on the tank to get the fumes / Vent stuff to work correctly?

Shold I try a PCV from say a 3.9 magnum v-6 or are they all the same anyway.


When I just changed the oil last week I poiured the new stuff in and it was black as soon as I started the car up and checked the dipstick.. YUCK..



Thanks,


Greg
Author:  SlantSixDan [ Mon Mar 30, 2009 8:24 pm ]
Post subject:  Re: NEW Issue with this EFI Vent / PCV Setup
Quote:
So for the last 2 oil changes My oil has been Really Dirty - Basically since I have switchewd to EFI and got the Charcoal can etc. connected up to the intake correctly.


I do have The PCV line and the Charcoal can Vacuum line connected to one Single port on the intake VIA a T - Less fittings and drilling that way.
Oops, no.

Charcoal cans do not just get hooked into manifold vacuum like that. Hook it up like this.

Also, you will want separate ports for PCV and charcoal can purge, depending on exactly where on the intake you've presently got them hooked up, and via what combination of tees and fittings; remember that you need to assure adequate flow volume for both functions, and that you really want to prevent crosstalk between the two.

And yes, the 3.9 PCV valve will be fine.
Author:  Greg Ondayko [ Tue Mar 31, 2009 5:39 pm ]
Post subject: 
Ok, well I can Work Out another port on the manifold to move one of the fittings to.


I will take a look at what i have going on now, adjust fittings and routings as per correct spec.


As far as the standalone valve in the link, It says to hook it up to a source that has no vacuum at idle, yet Has full vacuum above idle I do not have such a port As all of my ports have full vacuum except maybe AT WOT Due to the EFI Switch here with no carb in sight...


Greg
Author:  SlantSixDan [ Tue Mar 31, 2009 6:17 pm ]
Post subject: 
That's easily enough solved with a closed-throttle switch, either NC or NO. Do you have one or can you install one? If so, you can use it to control a can purge solenoid in place of the can purge valve (or, depending on what you can/can't find in terms of can purge solenoid flow rates, use the can purge solenoid to control the can purge valve).
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