Question on Non Baffled Valve Covers

I don't mean to hijack this thread, but since you asked...

Perhaps you can reshape the baffle so that your intake will clear. Cut, section, weld...it would be worth the effort if it can be done.

Otherwise perhaps you could fabricate a baffle which fits in the same place and performs the same function, but which is more compact.

The air cleaners should be irrelevant. The vacuum source is from beneath the carburetor butterflies, not from the air cleaner.

The air cleaners are not involved in a PCV system, other than in some factory systems where the air cleaner is used as a filtered fresh air intake source for the crankcase.

Hope this helps.

 

Sounds good,Ithink Ill try something like that if I have occation to take my intake off,but honestly I never did like that 8 inch long tube sticking out from behind the fan,kinda reminds me of a oil puking rain-bird. I think I would rather swing a ford into it,kinda done with the sbc thing.It just runs so good that I cant bring myself to do it.

 

You don't have to run breathers on the valve covers on your engine. The oil fill tube on the front of the intake is where the air enters the engine on your year engine. Get a reproduction PCV fitting for the rear of the engine from a Chevelle or Corvette supplier. It's held in with the same 1/4" bolt as the road draft tube used.

Baffles are needed when using the old M/T valve covers on the more modern Chevy engines but not on yours.... much ado about nothing.

 

Sometimes a few pictures are worth a whole bunch of words...(photos "stolen" from the internet, not particularly handsome, but at least handy)...


This is the vacuum source. The arrow points to the in-line PCV valve and the angle fitting which draws vacuum from below the carburetor butterflies.


This is the external hose fitting on the back of the early '60s block. I understand these are reproduced now, or you can find them on eBay. It is designed to be used inconjunction with an internal baffle, not by itself.


This is the "tomato juice" can internal baffle. Its purpose is to prevent oil mist from being drawn into the vacuum line while at the same time permitting harmful combustion byproducts and water vapor to be drawn in.


This is the vented oil fill tube on the front of the engine. It has a course steel wool filter to prevent big objects from entering while providing unhindered fresh air flow into the crankcase.

There are countless other ways of installing PCV systems on other engines, with or without valve cover holes, but the photos are of an early '60s Chevy smallblock with the breather boss cast into the rear of the block. Other examples can be found by google-imageing the topic in various ways.

Though some may poo-poo the idea of proper baffleing and of properly operating Positive Crankcase Ventilation systems in general, they greatly help keep engine oil clean while making the car much more pleasant to drive at the same time.

A properly operating PCV system will also help keep the exterior of the engine clean as well by minimizing "gasket weeping" caused by internal engine pressure and by eliminating oil blown out the vents as well.

A neat, functioning PCV system adapted to a high performance engine is also an indicator of the degree of skill, thought and care the owner has put into building his ride. It's a win-win deal for all concerned.

 

Talk about a lot of info!!!
Great.
And the pictures really help a lot too.
Some clarification on my engine that perhaps I should have mentioned in my original post.
* The tomato can is not there.
* The heads on my 283 are 305 HO heads
* My manifold does not have the hole, or a boss for the front oil fill.
Soooooo......

Sounds like maybe my best option is to:
* Block off the back down tube hole
* Get a baffled grommet and use the regular PVC set up, or get (or make) one of the early Olds type extenders mentioned here that puts the PVC valve out of the valve cover..
What you think of that??
Cheers,
Bob

 

If the engine on the original post is yours, here's what I'd do:



Block the hole in the rear of the block with a freeze plug;

Change the Holley valve covers side-for-side (to put the hole with the rag in it at the front of the driver's side);

Use a baffled grommet in the hole with the rag along with a right-angle PCV valve;

Run a short length of fuel/vapor hose from the PCV valve to the big port on the front of the Edelbrock/Carter carburetor;

Done.

 

missysdad1,
Yes, that picture is the engine I am talking about.
Thanks for all help. I will do as you suggested above.
I am happy now.....damn, love this forum!!
Cheers,
Bob

 

This is the setup I put on my car(I know its a muscle car). I put some thought into it to design a system that was going o give me the most bang for the buck. Most of our cars dont have air conditioning,so we are going to be driving at low speeds with the windows open. Most of them run somewhat rich and make a lot of stinky vapor in the crank case. The end result was always and engine that stunk like a junyard full of old taxi cab engines. The biggest issue for me was keeping stink out of the passenger compartment. Here is what I have.

A typical PCV valve in a baffled valve cover hole. I had to smash the baffle to clear the roller rockers,but it seems to be fine. The other side I took the baffle out and used a Mopar style breather with a 5/8" piece of heater hose just shoved into a hole in the base of the air cleaner. My line of thinking was that when acclerating the pcv valve gets nearly no vacum,and the engine is making the most blowby. Using a breather alone would have left me with stinky vapor chugging out into the car. This setup allows the stinky vapor to get pulled into the air cleaner by the slight amount of low pressure that is caused by the air filter. All the OEM's did this,GM used a crappy setup with the gauze breather in the air filter housing which left most tired engines with an air filter housing full of dirty oil. Mopar used a superior setup with a breather full of steel guaze on the cover before the vent tube. The oil that is drawn up just drains back down into the engine. You can get the breathers in the racing style like mine or in the oem style which is basically round with the tube coming out the side. The OEM style is more retro looking and would look more at home on a traditional car.

Aside from the "late model" look,this setup shuld be doable for you using basic period correct looking parts.

Good luck.

 

WOW!!! I was just about to ask the same question! I also have a non-baffled valve cover on my straight 6...and i'm tired of my engine drinking oil.

this forum is great! there is so much great knowledge out there!

 

Thanks for tips on this. I do have one of those under carb plates, and I picked up some more risers and one of them was tapped. I believe the motor is a late 70s truck motor and the block does not have provide access to the crankcase.

I assume I need to pull from the valve cover on the passenger side then? That kind of sucks that I need to drill into the old valve covers or can I pull from the base of the intake that goes into the valley?

Here is my current setup. The riser the wolf whistle is mounted on does go into the valley, but it is closed off, I just used it as a mounting point. Can I pull from it for a pvc system and not have to mess with the Valve covers?

Thanks for the help
RustyNCA

 

I think I'd use a '64-'65 Corvette oil filler tube and matching '64-'65 Corvette NON-VENTED cap for access to the crankcase.




Then I'd hook it up like this, using a threaded PCV valve where it says "metered orifice" on the diagram:



(IGNORE THE PART OF THE DIAGRAM SHOWING A CONNECTION TO THE AIR CLEANER - THIS IS NOT NECESSARY ON YOUR MOTOR)

The breathers already mounted on your valve covers will suffice for fresh air intake so no other changes will be necessary.

Hope this helps!

 

Thanks Missysdad. That looks perfect for my problem and what I already have.

I could use a short run from there to my first riser and run a pvc there.

Thanks a ton
RustyNCA

 

Ahhh...probably not.

Your PCV (not PVC - that's plastic pipe) valve vacuum source needs to be just below the primary butterflies of the most active carburetor in order to be most effective. That would be the center carburetor in your case.

Keep in mind that this modification will effect your mixture - it's like a big vacuum leak - and you may need to compensate in some way if the motor begins to run lean.

By placing the PCV valve vacuum source just below and between the primary butterflies you minimize the effects of the vacuum leak and do not localize the leak so that it leans any one cylinder more than the others.

Early '60s Chevys did use a "metered orifice" in leu of a PCV valve. This might be a good alternative to a modern PCV valve in your application if you run into a lean situation. A smaller orifice might mitigate the lean-out to an acceptable level without having to re-jet the carburetor.

All I can suggest is that you try it and see what happens.

Good luck!

 

Hmmmm. So I have a 70's SBC in my Merc and want to run old Chevy script valve covers instead of the gross Edelbrocks that are on there now. I drilled a hole in one side for the PCV valve.

So I guess I can use a baffled grommet in that side? And do I have to drill the other side for a breather, or can I get away with no breather??

I used to have a 79 Chevy Malibu and it only had the PCV and nothing on the other side, until I put some b/s chrome vc's on there...so maybe I'm good with just in the PCV?

 

PCV stands for positive crankcase ventilation. In essence it causes a mild vacuum in your crank case. If you are not running a road draft tube, a vacuum pump in the crank case or a pcv you are going to have problems. Your crank case will build pressure causeing poor drain back and ring flutter etc.

I have cheap cast rocker covers on one of my engines. I bent up a simple box out of brass shim stock and it is held in place by the grommit that the pcv goes into. Works like a champ you can also purchase baffled pcv grommets they are cheap and they also work.

Without the baffle you will suck oil out of the engine and into the intake that you reall want to keep in the engine.

 

You need to have a fresh air inlet somewhere in the system. The fresh air inlet should be across the block from the PCV valve vacuum source to work efficiently.

If you want to use the old style script valve cover you've already drilled for a PCV valve you can do so by using a baffled grommet. Right-angle PCV valves are available and make the installation very clean.

Drilling the other script valve cover in the opposet end and installing a baffled grommet with a breather would be the ideal solution. If you do this neatly nobody will notice that your setup is not original.

Or, you could use an old-style VENTED oil filler tube for a fresh air intake if your intake is drilled for one. To be most efficient, place the PCV valve as far away from the fresh air inlet as possible. You can trade the valve covers side-to-side to accomplish this if necessary.

Hope this helps.

 

Okay, noted about running it to the middle and what you are saying makes sense.

Not sure if you can tell, but I am running one of those 1/4" plates on the middle carb all ready as a source of vacuum for the horn. I can run that as it would be as close to the butterflies as I can get and run the air horn to the port that someone drilled on the riser.

Thanks again for the help.
RustyNCA

 

I have an Edelbrock AVS 800, my intake has no ports for pcv, I have breather caps on each side of my engine in the valve covers, they have proper baffles, I have had the pcv connection capped on the carb. This seems to let the engine favor a rich situation and it smells like the barn yard just like the rest. If I take the cap off of the pcv port on the carb the engine runs a lot better, obviously it needs that air flow into the fuel mixture, If I run a hose from the passenger side valve cover and put a pcv device into it, run this to the carb and allow air to enter the other valve cover through the breather cap is this correct and efficient. So air into one valve cover through the engine, out the pcv and into the pcv port on the front base of the carb?

 

you nailed it Plumbero, you should be able to pick up a universal PCV valve at any parts store with a 90* hose adapter on it, stick it in the grommet on valve cover on the passenger side and run the hose to the port on your carb and you are good to go.

 

Perfect, Between the pcv fix the plug re gap and the fact that I just set up my wye pipes to run open headers the neighbors are going to have a Saturday for the books, I think I may go by the ATM and pick up a little cash for bail money just in case, thanks guys.

 

Plumbero, your wit always entertains me. let me know how it all works out, hopefully you'll wake that puppy up.

 

dam i learned alot from this thread, keep up the good work guys

 

Yep, you got it.

 

If you ever took one of those coarse mesh breather caps off an old engine and tapped it in you hand or on a bench, alot of small gritty rust bits comes out.
If that was your fresh air source of venting I believe those rust pieces would find their way into your engine.
Personally, I avoid those types of caps and use the small air filter type for the fresh air inlet.

 

That's an excellent point, luckyuhaul. A thorough cleaning would be a very good idea before putting an old breather into service.

Thanks!

 

How would you adapt a PCV to a flat head 6 Plymouth? It works fine with the downdraft tube but gets oil mist all over the underside of the car and the oil gets dirty quickly.
Or, should I just leave it alone?
Great site for any info you need for these old cars!!
Paul

 

I have seen a kit offered on eBay for flathead Ford engines that might adapt to your Plymouth.

It consists of an adapter which fits a small diameter rubber tube to the road draft tube hole. The tube runs to the vacuum fitting below the carburetor which services the windshield wipers if I recall correctly.

It uses the "metered orifice" principal instead of an actual PCV valve...a relatively small orifice to avoid excess lean-out.

The flathead Ford V8 has the road draft tube mounted high on the engine and is not baffled, as I recall. Your Plymouth may have a road draft tube mounted lower on the engine and baffled internally.

It is important that the vacuum source be baffled to prevent sucking oil mist into the tube while at the same time allowing water vapor and combustion byproducts to be pulled in and reburned.

It sounds from your reference to "oil mist" from the road draft tube that your motor might have excess blowby from worn rings, etc.

I don't think this system will accomodate the blowby from a heavily worn engine. It just doesn't have the capacity due to the small orifice.

So I'd suggest that if your engine is worn that you rebuild it before you consider adding a PCV system.

Let us know how you make out.

 

Well my pcv issues are solved, that worked well, I think I over gapped my plugs at 50, I get an odd rumble at about 4500 rpm, It may also be the springs in my distributor, Then I have to set the vac in the adjustable modulator.Bit by bit she is getting faster and faster. Thanks again.

 

Someone should sticky this thread because it has lots of good info. Or put it as a tech article or something (if you guys have those here.) I honestly didn't really know much about engine venting, etc before I read this and probably wouldn't have thought of it unless I browsed this. Thanks guys!

 

Thanks MD1,
Apprciate the info. Maybe the oil is from the burnt #6 exh valve that I am trying to change now (I'll post questions on that in another post). The road draft tube is on the side at the back of the engine and is pretty high on the block. The engine is a 1938 (in my 38 coupe of course) and when I checked compression it was pretty good across all cylinders (85 and higher) except #6 cuz of the bad valve. I'm running dual 2 bbl carbs from a 1983 escort on an Offenhauser intake and Fenton nock off exhaust headers. Runs great when all cylinders are firing. I dont think the rings need replacing just yet. Maybe I'll just leave it alone for now and fix my other problems first but its tempting to go to the PCV system and with my setup there should be a port on the carbs for this purpose.
Thanks,
Paul