I've been researching this, and have never figured out a straight answer, so here it goes. I reserve the right to be wrong....

According to my chasis manual and assembly manual, my car (66 442/4-speed/AC with K20 (closed crankcase circulation) should have a 393581 Air Cleaner. I think its closed, flash chrome, with the crankcase breather pipe grommet in the rear side of the snorkle. Unless theres another air cleaner thats open (as I first understood all 4-speeds should be) with a breather hole in the base. I'm just not sure.

Anybody have a 66 4-speed (I believe a QW engine code) with an original air-cleaner set up with K20 or can confirm what I (think) I'm reading correctly? My car was a Fremont built, California bound car (2nd week of June) and did NOT come with A.I.R., I have the protecto plate and the head numnber (passenger side) matches the POP and they are non emission heads (no plugs) on an original motor.

Pics please if you have any? Thanks for the help!

 

My 66 is a Fremont car that DID come with A.I.R. It was originally a 4bbl car. I have the original air cleaner and it is as you described. Flash chrome and the breather grommet on the rear side of the snorkel.

 

Thanks! Was your car an automatic or 3/4 speed?

 

Automatic. I should have mentioned that. I just re-read your original post and saw the 4spd reference. The parts book shows an open element air cleaner for 4spd cars. The base for closed combustion cars is P/N 6422912. This is different from non-closed combustion cars. The lid is the same for both (P/N 6421832).

 

Awesome. Are you seeing that in the chassis manual? I couldn’t find anything but that’s what I was trying to figure out. My car has a 66 orange 330 4 barrel closed air cleaner on it now, with a 66 automatic crankcase vent and tube that would be correct for that air cleaner. All are aged as original.

So either the factory didn’t have the right parts for k20 as you spec’d out and put this on to keep the line moving, or, it’s been changed. The original owners daughter/son in law said it was always orange, so who knows.

For a chrome one, it seems I’m in search of a typical chrome top and a specialized k20 hole base.

Dod yoy you happen to see how the vent is attached from the valve cover to the base? Wicked helpful and I very much appreciate it.

Heres what I have now.
[img]https://classicoldsmobile.com/32c2159c-2b9e-48ca-88f1-b546f0d7ce26


[img]https://classicoldsmobile.com/cbae4bf1-5484-4262-b075-66e0db7122ec

 

This info comes from the factory parts book, specifically the Jan 1972 printing. The air cleaner parts are in Group 3.406 for the base (called a "plate") and Group 3.410 for the lid. I thought this was detailed in the PIM (Assembly Manual) but I'll have to go dig out my 1966 version.

 

Thanks, Joe, I don't have the parts book, just the chasis and the assembly from 66. I tried to attached pics of what I had, doesn't look like it worked so I added them in album if you have access to that. I now know what I'm looking for, base and top, and just need to figure out the plumbing between the valve cover and base. Of course knowing what I'm looking for and actually locating the parts is a whole other story.....

 

Yes, I see it now in the assembly manual, on my copy page 227, 6-3.3

The thing is; the 4-speed diagram shows an open element and the "pipe" 393662 going under the baseplate, assumably to a plate fitting. That's the right side valve cover, and the left (drivers) should then be what? A breather? That wouldn't be a closed system. My car has a PCV valve off the right side to the front base of the carb, and the left valve cover has the filter assembly (6421883), grommet (387197), and pipe (391556) (all on the same section 6-3.3) going to an orange 6421929 closed, short snorkle air cleaner assembly. Now I'm really confused.

 

The PCV valve would be in one valve cover and the other would have a filter with a hose that went to the fitting on the underside of the air cleaner.

 

Makes sense, figured that after I posted. Again, many thanks, Joe. I just posted in the wanted section for the correct base, any chrome top from a 66 or 67, and even a regular breather if I decide to just convert it from the CCV system. I'd rather keep it correct, but I'll see what's out there. Thanks again, if you see any parts around let me know.

Mark

 

The "filter" used in the valve cover is P/N 6424244. It pushes into the grommet and the hose runs from there to the underside of the air cleaner.

 

So that's a common one, (good) and the hose I assume is just rubber...

 

Correct.

 

Was PCV on all 66s and 67s, and that was called closed combustion? Or an option.

Side note about car assembly lines, wrong parts were never put on to "keep the line moving." Sure, mistakes were made, but, most of the time, if you're missing a part, you can let it "flow" for a few pitches while you hot call them, then send your team leaders after the cars to retrofit.

 

I’ve never figured out what was in K20 other than it substituted the “open” crankcase vent mounted on the valve cover to a closed system but routing a pipe or hose from the valve cover breather to the air cleaner, in the case of a 3-4 speed into an open element air cleaner through the base, and an automatic into the snorkel via a pipe and grommet. I think the pcv valve was on all of the cars in 66/67.

On the stop the line comment, I agree that wouldn’t make sense. I do know 66 was the first year for “emissions” controls in California bound cars, (at least A.I.R. was).

 

For the 1966-67 model years, all cars got PCV. 49-state cars got an open breather on the valve cover opposite the PCV valve. On CA cars, the "closed combustion" simply meant that instead of an open breather, this breather in the valve cover had to connect back to the air cleaner housing. The issue was that the open breather on 49 state cars could still emit hydrocarbon-laced fumes to the atmosphere. The closed system ensured that these fumes were sucked back into the intake and consumed in the combustion process. Note that starting with the 1968 model year, all cars had the closed system.

 

This is what I was trying to explain to you when we talked the other day. The open element top is the same as the other 4 speed cars. Like the one I showed you is on my car. The base. Which is the same as the standard 4 speed base has a pipe that goes to the breather for the "closed type system" you have asked about. I am going to find you a picture of the base also. I have found those reproduced but hard to find.

Larry

 

While not exactly the same as OEM, many aftermarket companies sell an elbow like this that goes on the underside of their open element air cleaners to provide the hose connection for that breather.

 

Pardon my sleep deprivation caused ignorance, but where is the suction on this one that goes back into the carb for vacuum source?

So, automatic 442 with late year no snorkel cleaner could have the closed combustion port in the 4 speed base that setup used, I surmise. Also, I guess w-30 could have that too in the big chrome OAI cleaner?

 

I'm not sure what "vacuum source" you are looking for. The crankcase volume sees pulses. Those pulses can and do cause fumes to be pushed out an open breather on the valve cover (which is one reason why these breathers frequently have an oil stain around them). By instead routing the tube to the air cleaner housing, any fumes that are pushed out get sucked into the carb inlet along with the rest of the airflow. This isn't 20" of manifold vacuum, it's just a minor pressure difference but it's enough.

 

Ok, reason I was asking is some Other Brands, like Ford, lay out their PCV that one head has a inlet from the clean side of the air filter, goes through the block, and the other head has a hose to manifold vacuum, teed off with power brakes. It's a controlled vac leak through the crankcase. I don't recall GM doing this ever.

 

That's exactly how the GM system is laid out. Hose from the air cleaner goes to one valve cover (or both if it's a 70-72 with "dual ventilation") and PCV valve in the other valve cover (or intake valley) runs to manifold vacuum. Base of the carb or manifold runner tee to the PB hose is functionally identical. Again, the PCV valve is really a check valve that responds to pulses. These pulses can cause HC fumes to be expelled out the "inlet" side of the valve, thus the requirement for the closed combustion system. From the 1969 CSM:

 

Ok, that's what I thought I thought. Thanks.

 

so the 66 4 speed cars with ac all came with the closed air cleaner?
not just the California emission cars.?

 

where can i purchase this filter P/N 6424244

 

Do not confuse closed PCV with the closed air cleaner. You could get either open or closed air cleaner with either open or closed PCV. Calif 4spd cars still got the open element air cleaner. They also got the closed PCV, which requires the special bottom plate that mzack66442 is asking about.

 

Type 6424244 into Google.

 

Thanks Larry.

 

This might help. It's a Chevelle unit but may work or could be modified to work. The closed PCV system open element cleaners are very hard to find. Some of the other Chevy's used this style cleaner,so if you search around,there might be another base that will work.

https://www.ebay.com/itm/Chevrolet-C...YAAOxyVaBSo1sS

 

Thank you. That seems to be the consensus and what im
going to try. I’ll report back after I get it

 

Ok, the 67 Chevelle air cleaner base plate (AAC-8864) and spark arrestor (ATE 5695) look exactly like the one in the 66 Olds assembly manual, and...fits my stock Quadrajet perfectly. With the typical 3" air filter and a stock 66 chrome top, its perfect. So if you're looking for one, this is the ticket. Part numbers are from Ground Up (www.ss396.com). They are super helpful.

The K20 (Closed CCV) cars have the PCV valve on the drivers side valve cover (open CCV had an open vent there) and the passenger side has a "pipe" (1" with nipples on each end that fit into the valve cover grommet on one end, and goes to a rubber hose "coupler" that attaches to the vent elbow in the air cleaner base on the other.

While the Chevelle base works great, I'm still looking for the right vent pipe. In the mean time the mid 60's Chevy Big Block vent elbow from a 67 Chevelle (part number APT-3509) works, you just have to use a 1' I.D. rubber hose to replace the metal pipe i'm missing...

Thanks all for the help, I hope this helps somebody else who's also looking for the closed crankcase vent system that works.

Mark

 

Glad I was able to help
Larry

 

Couldnt have figured it all out without your help Larry. Thx again.