I've done a lot of searching and a lot of reading about this, but haven't found anything that helps me with my particular situation, so please spare me the "search" lecture. Here is my setup:

85 GS
S5 13B - rebuilt
Camden 5" supercharger
Holley 650 double-pumper

Last night I discovered that I have "lung mustard"...the creamy liquid that forms inside the oil filler tube and causes rust and thinned out oil if you don't ventilate the engine properly. I thought I had vented it properly. I have a hose running from the fitting on the center iron to the charcoal cannister, and I have a breather on the fitting on the side of the oil filler tube.



But, apparently this isn't enough, so I'm planning on putting a pcv valve on it. But I'm not sure where I can connect it. There are two small ports on the carburetor. According to the Holley paperwork that came with the carb, the upper one is for connecting to the distributor advance, and the lower one the air cleaner or pump valve (whatever that is).


There is a larger port at the base of the carb, that Holley says is for the PCV valve. I have this one connected to the brake booster right now.


My question is, can I use the small port at the base of the carb for the PCV valve? If I put it where Holley says to put it, then where can I connect the brake booster? Can I put a T in that line and connect both the brake booster and the PCV valve, or will one of them get all the vacuum and the other none?

One more thing I question is the obstruction in the smaller fitting on the charcoal cannister...is this normal? Also, is there a way to test or clean the charcoal cannister?


Thanks,
Rich

 

Well, someone will be along shortly to give you all kinds of details on how to fix this. But for now, long story short, you have to feed a vacuum line to that nipple on the filler tube. Keep the oil under vacuum basically, and you won't have an issue. Proper methods include the use of a pcv valve, but I'm not too sure on just how necessary it is. Anyway, that's what I know about it. Good luck.

 

When I get home I'll try to dig up information on my PCV setup.

Off the top of my head I know this

1) Anything on the carb that gives vacuum will be fine for PCV. In my experience, the lower on the carb body the fitting is, the more vacuum it tends to have.

2) The threaded part of the PCV valve goes towards the vacuum source.

IIRC, I vented the charcoal canister to the carb directly as well.

Then the pcv valve's hose connects the theraded end of the PCV to a carb vacuum, and the other end of the PCV valve to the oil filler tube. The fitting on the intermediate housing goes to a clean air source (such as your little filter doohicky.. where'd you get that anyway? I want one!)

Jon

 

All I have read about the engines is the whole basic functionality of the engine is based on vacume and pressure. I had a bad vacue leak and got the same frothy oil and rust in the filler tube. After I fixed the leak it didnt get any worse but didnt really go away either. I think the engine and the oil pump is designed to keep the block at a high vacume pressure to make it optimal. But again i'm not really sure and dont have any super soild facts to back that up or anything. If an expert could enlighten us that would be great because I would like to know as well.

 

Thanks Jon - I appreciate your input. I'd like to see pictures of how you have yours plumbed. I got that breather at AutoZone.

Rich

 

i found that in my oil filler tube.. what do i do to "ventilate" it drill a hole in the filler tube?

 

do not use the the vaccum source on the metering block. the one under the primary float will siffice.

 

OK...thanks. Now another question. Do they sell adapters to adapt from one hose size to another? The fitting on the oil filler tube is larger than the one under the primary float, so I would need two different size hoses. Most of the PCV valvle I've seen have fittings similar in size to the one on the oil filler tube.

Thanks,
Rich

 

i left mine open and had that goo almost within the first few weeks of driving. without a PCV the filter really does nothing but stop it spraying oil vapour out.

i'm not going ot bother going with the PVC, but your engine looks pretty clean and probably worth it! using the vac. outputs on the holley should work fine since they are all the same, im just curious as to what effect the dirty oil vapours going into the carb will cause.

 

They make hose barbs that have a different size on each end. You might find a plastic one at an auto parts store, or a brass one in the plumbing supply section of the hardware store.

Oil vapors won't harm anything, they can gum up the intake if there is too much blowby. Look at it this way, it's just adds to the mop output. I remember back in the days before emissions, instead of a pcv, there was a blowby tube that came out of the vavle cover and and terminated near the bottom of the engine. If the oil rings or valve guide seals were gone, it looked like a little exhaust pipe, blowing out blue smoke.

Do not tee into the brake booster line, not only could you loose vacuum, you could get an oily buildup that works it's way into the booster. If you can't find a nipple on the carb, you may be able to add a nipple to the bottom of your air cleaner.

 

My old 3 had this and I raced it for years without a problem, what are the reasons for eliminating the issue?

 

For the different hose sizes, I just got a medium sized hose that would stretch to be big enough, and could be clamped/ziptied to be small enough.

Here is a picture of my setup. There are three hoses, so I used different colours to distinguish them. For the "red" hose, you can just use that little air filter thingy instead, though you'd have to get a 90' elbow to get it to stand upright and not vibrate against the engine (which would annoy me).




Green Hose - Starts at a carb vacuum source. Goes to Threaded end of PCV Valve. Then goes to Oil Filler Neck. The vacuum from the carb (along with the PCV to prevent massive vacuum leak) stops the buildup of sludge.

Red Hose - supply with a fresh air source. By sucking vacuum from the filler neck, we're sort-of "reversing" the vacuum flow of the stock system. This would normally be the vacuum source for the charcoal canister in a stock rat's nest setup, but now that we're sucking at the oil filler neck, this needs a fresh air source.

Purple Hose - to deal with the evaporative emissions from the charcoal canister, the hose from the canister needs some sort of vent or light vacuum source. The nikki has a carb vent that works fine for that. No real vacuum pressure, but a good place to vent evaporated gas to. Worst case scenario, you can plumb this hose into the bottom of your air filter canister. There should be enough pull there to allow the charcoal canister to vent into the carb instead of stinking up the engine bay.

Jon

 

Now this is just what I've done by reading the stuff I searched up and found in other PCV valve threads.

I want to try hooking the charcoal canister to the spot on the intermediate housing, but I don't know if that would put too much vacuum on the canister... or what it would change really. Might be worth it.

If anybody has any suggestions at all on things I could do differently, or any reasons to back up what I've done (or even change it) feel free to speak up.

I'm not perfect, but this has worked well for me. Solid idle (between 900rpm and 1100rpm depending on weather, air pressure, humidity.. not bad for a car w/o an idle compensator) and no buildup of sludge.

G'night all

Jon

 

Thanks Jon -

My carb came with a fitting you can put into the bottom of it, so I'll put that in and connect the charcoal cannister to it, put my breather on the nipple on the center housing, and connect a pcv valve between the carb vacuum port and the oil filler tube.

Rich

 

You guys are making life too complicated. Just drill the oil cap and put a fitting in it. Its that simple

 

Lots of good advice. As FB II says that vacum source matters. A PCV system uses manifold vacum (as does power brake booster). The upper nipple in your pic is "carb" vacum. You don't want to use that. As per Trochoid, don't "T" the brake booster. Any oil gets into it and you can kiss the internal diaphram goodbye ($$$).

The easy way to tell manifold vacum from from carb vacum, is that manifold vacum is always after (or in this case under) the throttle plates. If you wanted to make a very nice job of it, you could drill and tap your base plate at the same location as the brake booster, but on the opposite side so it would be near the oil fill tube. Your engine is so nice looking, I'm assuming you don't want some patched together affair, but a clean, neat install.

 

thats it? so what does the fitting do just let the moisture escape? and how would this effect a turboed car?

 

I installed a PCV valve today. I moved the breather from the oil filler tube fitting to the fitting on the center iron, then installed the PCV valve between the oil filler tube and the vacuum port on the carburetor. As I'm writing this, I realize that I put it on the wrong port...I'll need to move it tomorrow. Also, I couldn't find the fitting that came with the air cleaner to run a hose from it to the charcoal cannister, so the charcoal cannister is not connected right now.









Rich

 

what aboot in a turbo application? intermediate housing to in front if turbo and filler neck to manifold vaccume with a pcv valve?

 

I agree. That is exactly what I do is simply drill a hole on top of oil filler cap. I have a filter there, just so nothing dirty gets in. Its not that WACKY at all!!!

 

this is the exact pcv valve i used when i had this problem many months back and studied a particular thread on this matter to understand just how to set this all up. this is the only pic i have right now but will get a closer up one if needed. all i did is connect a hose to the port on the center housing with the pcv valve in it and tied it into the vacuum source for the brake booster coming off the intake. then ran a small hose from the port on the filler neck and drilled a hole in the bottom plate of the air cleaner on the clean side to put it in. solved the problem right off the bat.

 

I can get a pvc at autozone right?

 

yup you should be able to get it from there ...

 

way to dig up a year old thread, lol. u can get a pcv valve from a walmart if youre allergic to autozone like me

 

Yea thats pretty bad of me. I used search then I saw it was only 2 days ago cause I didnt look at the year. Im wrong