The Stovebolt Site Forums The Shop Area Engine Shop Adding a PCV valve

I have a 261 engine in my '55 1st series truck. Plan to remove the draft tube and install a breather with a PCV valve. Plan to run a line from the PCV valve to the intake manifold. I have vacuum wipers that are hooked to the intake manifold. The vacuum wipers work fine. The PCV valve line and the vacuum wipers line will share the same fitting on the intake manifold. Will the vacuum wipers and the PCV valve function properly?

short answer: NO ... check a shop manual, there's info in it about the factory setup

Bill

The shop manual does not have the information, at least I could not find the information. My thought is most trucks with the PCV valve have electric wipers. My existing vacuum wipers were rebuilt by the wiperman.

try 55.2 manual ... the PCV was an option well before the electric wipers became standard

Bill

Larry, PCV is not a huge inpact on wiper operation, low engine vacuum under load slows them down. I have two bone stock 261 engine I pulled as runners, a '59 and a 55.1, both with factory PCV system. Vacuum port on intake manifold below carb has a brass connector with ports for PCV, brake booster & also wipers via the vacuum pump on the older one.
Do you have combo fuel / vacuum pump? That was there to assist the wipers under lo engine vacuum. If you don't get one! Other options include adding a vacuum storage tank with a check valve (but sooner of later you run low on vacuum on long hard pulls) or electric vacuum pump.

Install a fitting on you're air cleaner for the PVC sys.Than you can run the line from the valve cover to the bottom of your air cleaner.


Pete

Link to truck pictures and NOS set-up.
http://www.flickr.com/photos/advance-design_parts_co/8129442754/in/set-72157631868452754

There's a guy over on the VCCA site who added a PCV to his 235. His handle is wawuzit. Send him a PM and he'll send you pics of the project.

See the pics of factory set up, we cut off the down pointing part of standard road draft tube and fabbed the same set up. And I can say it slowed or stopped most or all oil leaks in the motor.

I added a PCV valve to my 216. I opened up the top of the tube, blocked the holes leading to the down spout and drilled a hole in the cap. My PCV mounts in the hole. I use a ventilated valve cover filler cap. It didn't affect the wipers at all.

Where do the fumes end up going after it leaves the PCV valve?

I did this about 10 years ago, its on my website complete with part numbers. Works great. Something a person can do to keep the mod very clean would be to use the fuel pump with the vacuum connection.

52Carl,
the fumes go into the intake manifold and are burned. This setup keeps a flow of clean air going through the crankcase when the engine is running.

truchernix,
Did you use the hole where the vacuum wiper normally goes?

I put a fitting there to accept a second inlet.

Any idea of the volume of air that gets pulled through the PCV valve? I wouldn't imagine that it is very much. I had a 90 jeep that didn't have a PVC valve. It just had a tiny vacuum line that governed the air flow.

The valve itself regulates the flow. I tried to get one that was made for an engine with similar displacement. I believe it is there to also stop a backfire from getting to the crankcase.

I did this mod this afternoon and just finished the 2nd shakedown cruise and so far it seems to be working fine.
It feels like its running alot better but it could be my imagination
I'm hopeing it clears up the massive condensation condition thats just recently cropped up w/the cold weather and it should improve engine breathing as I discovered the road draft tube was just about completely stopped up when I pulled it. This engine was barely breathing.
I decided to go the same route as Deve and mount a PCV valve in a freezeout plug installed in the draft hole. Luckily the deflection plate was still in there so it may not suck up too much oil.
Vaccum wipers work and engine performance at all rpm is great & uneffected.
Parts used:
Purolator PV141 PCV valve
42058 PCV rubber grommet
47051 universal vaccum Tee
4' 3/8" gas line
1 1/4" freezeout plug
I spliced the Tee into the wiper vaccum line at the manifold. I measured the grommet where it seats when installed and drilled the hole in the freezeout plug a hair smaller (used a step bit).
All in all it took maybe an hr.
Vaccum Tee PCV valve

Yeah, the original writeup is in the how-to section on my website. I came up with it on my own, but then I had health problems that took me 5 years to sort out, and never tried it myself. Others did and reported back to me that it worked really well. Last year I ran my 261 with the mod for the first time and tested it out on an engine stand. Worked flawlessly and I feel it also improves performance, but like you, cant prove it.

I am pleased you tested it on a complete truck with the wipers because that was a big concern.. was there enough vacuum to do both. Another idea is to use a fuel pump with the vacuum connection, but haven't explored that idea fully. If that worked, that would be a better idea since the hose length would almost be nothing.

Thought I'd update as I've had to modify the PCV setup.
Theres so much oil misting going on in the crankcase that the manifold was sucking so much oil that it was dripping out from around the manifold vaccum fitting after shutdown. I could literaly pour some drops out of the vaccum line. The oily film that normally collected at the tailpipe quadrupled.
Oddly the engine still ran great and didn't smoke but since I already loose enough oil to leaks, I didn't want or need another source that'll rob that Texas Tea...

I hated to do it but I needed to extend the PCV valve out further from the crankcase and implement some kind of oil/blowby separator and I couldn't think of a better device that I had on hand than the stock road draft tube assembly I had removed. So I cut off the down tube portion approx 1.5" from the main body, glued a rubber grommet in the hole and mounted the PCV valve there.

This seems to work pretty good but I haven't gone on an extended cruise yet.

Also, I tried another larger PCV valve just for GP and it didn't work out. End's up for the PCV valve to work properly on these stovebolts they have to have "some" built in restriction to vaccum flow. The larger PCV valve sucked so much vaccum that it acted like there was no valve at all. The engine would idle just as if the manifold vaccum port was unplugged and there wasn't enough vaccum to work the wipers. The smaller PCV valve thats been spec'ed in this thread seems to work out fine. Just an FYI to others that may try this.
Dave

The engines that come from the factory all have baffles built in for the pcv valve. If you look on the underside of a valve cover that is meant for a pcv valve you can see what the baffle looks like. The early Chevy small blocks all had a baffle in the valley above the lifters for the pcv that exited at the rear of the block. It may take making more of a baffle to get the system to really function correctly on a 216/235.

Did the factory valve covers that were used with the factory PCV systems on 216/235/261 engines have baffles inside the valve covers?

I'm guessing the reason the OEM setup used the long/modified draft tube is to let the oil run back down to the crankcase.

OEM draft tube/ pcv: http://s142.photobucket.com/user/551stsuburban/media/1955%201st%206400/005_zps3d5a38e6.jpg.html

I've also woondered how effective adding a couple lifter valley stand pipes would be to the 235. http://pitstopusa.com/i-5070741-allstar-performance-sb-chevy-lifter-valley-vents.html

When looking at the bottom end of my 235, there isn't really any direct paths from the valve cover to crankcase.

"direct paths" for oil return from under the valve cover to the oil pan?

Sorry if I misunderstand your statement, and sorry if my response is totally incorrect (or, if I am totally missing your point): oil that is under the valve cover drains-down behind the push-rod side cover through the push-rod holes through the head. I think there are two drain holes to the pan behind the push rod cover, between/behind lifter-journals 2&3 and 10&11?

I'll have to look again, I didn't see the oil drain paths.

Realistically though, addign a vent that is not an oil drain path would theoretically, help keep oil out of the PCV system.

I just wanted to clarify my earlier post. I was not saying a 216, 235,and 261 ever came with a PCV valve in the valve cover. I was referring to engines that did have a factory installed PCV valve in the valve cover. Sorry that I didn't make it very clear.

don,

My question was not pertinent to your comment - sorry.

Factory PCV set-ups on 216/235/261 engines did not have a PCV valve on the valve cover.

The original option of PCV was on the modified downdraft tube. Later it was located on the valve cover. Since the fumes of concern, namely water vapor, will rise once the engine oil warms up, the valve cover, being the highest point of the engine, would be the logical place to put the PCV valve. Would a non-vented 235 valve cover with a hole drilled in it for the PCV valve and a baffle under it provide the best option for evacuating water vapor?

Are you referring 235/261 PCV systems when you state "Later it was located on the valve cover. . . . "

Great convo.
I'm still sold on having a PCV system on my 216 for several reasons. I like the fact that normally produced vaccum is used to evacuate the blowby at all engine rpm, even idle. This would seem to be a huge improvement over the simple road draft system that needed air moving across the downdraft tube's opening to get the same effect. At engine idle and low speeds there wouldn't be enough "draft" so I guess evacuation must have depended upon simple convection.

In looking at engineering drawings/spec's you can see how the Stovebolt ICE evolved.
With regards to the PCV system, it seems they went from a top fresh air intake and bottom blowby exhaust to the complete opposite and this is how modern engines also deal w/it.
Is the newer way more efficient or just cheaper for the manufacturers to implement?

This is makeing me rethink my approach to implementing a PCV system to the 216.
I could seal up the vent slots in the valve cover and move the PCV up to same and either install a small air filter at the road draft tube or route a hose from the road draft tube up to around the air cleaner.

My high mileage 216 makes quite a bit of blowby and it steams/smokes through those VC slots well after shutdown. I would think having those gases venting out is a good thing. Would a vented oil cap be enough to allow these gases to vent and would the vented cap effect the ability of the engine vaccum to pull blowby up from the crankcase?
Just thinking out loud here.
Dave

No, I meant a bit later.
Carl

Imho, with a 216, I would stay with what you have. It is far better than stock.
Carl

Is there something wrong with the setup described on my website? So far I haven't heard any negative feedback. Everyone who has tried it, likes it. And for the 20 bucks or so it costs to do it, seems like a no-brainer. But I WOULD like to hear contrary opinions.

Deve, I did an update, 1st post on pg 3 explaining that I was going to have to modify the modification it's pretty self explainatory.

Post's afterwards by me is just thinking out loud and looking for opinions.
Your mod works great but, in my case, It needed alittle more modification.

Dave

On the original engine, there is a metal piece on the inside that keeps the splash from getting sucked into the system. I ran my 261 for hours now and there isn't any evidence of oil getting sucked into the system. If that piece wasn't there, it WOULD suck oil into the system. As I remember, and its been years so I could be wrong, that metal splash guard was held in place by a single screw. I can see it being removed and forgotten easily. Pretty important to have it in place because even without the mod, the road tube would leak more oil than it already does.

The baffle is still there and very visable thru the hole.
As I explained, my 216 has alot of blowby. I had the head rebuilt but not the bottomend of which I estmate has atleast 100k miles on it. The speedo was broken at 99459 miles and I've added 4k since. This no doubt contributes to increased blowby and oil suction through the PCV system. There was enough oil drainage from the draft tube after shutdown to warrant a drip pan.
The blowby has decreased alot with usage but theres still quite a bit. There is slight steam/smoke from the VC vent at idle, but nothing like it was when I 1st got it running. Same out of the road draft tube w/the PCV removed.
It'll be getting alot of road testing this weekend.

This is good to know because lots of us have engines that were frozen when we purchased the truck and have unknown characteristics and it means maybe the valve would be better placed further up the line in some cases, or reduce the suction in others.

After scraping some crud out of engine, I actually found the oil drain back holes. Looks as though there was a hole above distributor gear, but wasn't machined on later models. Maybe drilling it out and adding a standpipe may help with ventilation.

Anyhow, I saw someone mention putting a breather on the draft tube and mounting the PCV on the valve cover, I kind of like the idea.

A clamp on air filter would go right over the draft tube.

http://www.jegs.com/i/Airaid/028/775-138/10002/-1?parentProductId=

Dads50 (why do these handles remind me of my awkward CB radio days?)...I just followed your links to Tim's website, another treasure trove of info I wasn't aware of. I love the photo of the happy newlywed's in front of the old panel truck....all I can say is it must have been love, what a gal !
Thanks,