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Old 06-21-2012, 05:29 PM   #1
CoolKidsInCorvettes
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Default 77 PCV / VAC help - Oily fluid in carb *PICS*

Hey all,

So i've done quite a few searches and feel like I have a good idea how to re route the vac lines for the PCV but have a few questions lingering.

My apologies if this is rudimentary, but I just finished a 3 month project on a Subaru BRAT so I've got the subie system on the brain which is probably the cause of my confusion.

Anyways, as you can see in the photos:

1. PCV is on Pass side. It should be on the drivers side to my knowledge, as the rotation of the crank acts as a "fan" of sorts and creates slight vacuum in the pass. valve cover anyways. The breather (inlet) should be on the pass side... correct?

2. The PCV is connected to the Vacuum port on the rear of the Manifold (Edelbrock 2101) via the orange nipple. Wouldnt this create too much vacuum and force oil directly into the manifold and perhaps cause a backfire through the carb? I believe this should be connected to the port on the front (dead center) of the edelbrock carb. via the large port covered by the black nipple (after the swap to the pass side)... correct?

3. Brake booster / T fitting - I believe this is hooked up correctly, but maybe it would benefit from using the port on the intake instead?

4. Vac Advance - Shouldnt this be on the front, passenger side of the carb instead of the drivers side? Not sure if it matters, but I believe it could if the carb is setup like the Weber on my subie.

5. What fluid / How the hell is oil in my carb top if theres no PCV plumbing hooked to the air cleaner? My only guess was that the PCV was blowing oil into the intake, causing a carb backfire, and spraying/seeping oil through any oriface it can find.. you can clearly see the pool of oil in the pic of the carb top (it only seems to be on the rear 2 barrels).
Another radical thought (which I believe is impossible, but may give you a laugh) is some idiot (drunk) tow truck driver neighbor of mine INSISTED that it could be brake fluid.... i know this has to be b/s as its a closed hydraulic system and if I was leaking, it surely wouldnt be from there, and the brakes would not function as normal... but still, pretty funny.

Any suggestions / tips / links would be much appreciated.

Thanks & keep it cool

CKIC

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Old 06-21-2012, 09:28 PM   #2
my 76 ray
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I'm not familiar with your manifold or carb, but the valve covers are on the wrong sides.
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Old 06-22-2012, 05:23 AM   #3
CoolKidsInCorvettes
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Quote:
Originally Posted by my 76 ray View Post
I'm not familiar with your manifold or carb, but the valve covers are on the wrong sides.

Indeed, I noticed that and believe I covered it in #1 above. I've read many different theories on the placement of valve covers / pcv / vacuum.. care to shed any light? the information can be quite convoluted in this forum at times.
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Old 06-22-2012, 09:09 AM   #4
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Okay, let's start with PCV. It should draw from manifold vacuum, mine pulls from the base plate of the carb, and in the pics (you're allowed to get closer with the camera, these things aren't camera shy! LOL) it looks like your carb has such a port in the middle of the front of the base plate. I can't tell how your brake booster is routed, but it should also pull straight manifold vacuum, and most, but not all have filters on them. As for the vacuum advance, that kind of depends on your engine set up. On some applications, ported vacuum works fine, others, manifold vacuum is what's needed (that's what I run). As for the placement of the valve covers, it doesn't really matter what side their on for the PCV. Think about it, the vaccum is the same on both sides, and the valve cover with the PCV in it, has the baffel so, what possible difference could it make what side of the engine the cover is on?

Now, oil in the carb, I can't see it in the pics. If the PCV is working correctly, there's really no way for oil to get into the manifold (unless there's a gasket problem) let alone the carb. Take the PCV off and shake it. It should rattle. If it doesn't, replace it. It's a one way check valve and if it's not working correctly, it can allow vacuum to draw from the crankcase when it shouldn't.

And as I'm sure you've noticed, the only similarities between a C3 and a subie is they both run on gasoline, and have 4 tires...
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Old 06-22-2012, 03:40 PM   #5
Easy Mike
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Your manifold vacuum fitting in the runner between the carb and distributor is headlight and/or AT only. No PCV from this fitting. Line from the base of the carburetor toward the firewall should be power brake booster only with no splices or tees. Most of these are metal pipes.

Correct PCV is from a port on the carburetor, usually near the base, to the PCV valve in the left side valve cover.

Swap your valve covers. That will put the PCV grommet correctly on the left. You do not need the aftermarket breather if you run the stock air cleaner set up and connection to the passenger's side valve cover.

I honestly can't see anything in your carb.

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Old 06-22-2012, 04:55 PM   #6
CoolKidsInCorvettes
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Quote:
Originally Posted by Easy Mike View Post
Your manifold vacuum fitting in the runner between the carb and distributor is headlight and/or AT only. No PCV from this fitting. Line from the base of the carburetor toward the firewall should be power brake booster only with no splices or tees. Most of these are metal pipes.

Correct PCV is from a port on the carburetor, usually near the base, to the PCV valve in the left side valve cover.

Swap your valve covers. That will put the PCV grommet correctly on the left. You do not need the aftermarket breather if you run the stock air cleaner set up and connection to the passenger's side valve cover.

I honestly can't see anything in your carb.

Sorry, Heres a better photo. I've also read that most aftermarket valve covers do not have some sort of a baffle/splash guard thing to prevent oil from being pushed up through the PCV. So, if thats the case, couldnt I just swap the valve and breather location only and leave the covers where they are? That is, until I find a set of covers with this baffle to swap in.

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Old 06-23-2012, 12:16 AM   #7
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Update:

Switched the PCV vacuum over to the correct port on the front of the carb & plugged the manifold port.

Car now idles pretty rough, but it seems like the change helped the drivability and acceleration off idle. What felt like a slight miss that had been getting noticeable over the past couple weeks has improved and i feel like I'll find a dirty spark plug or two from the oil blowby. So once that's done I feel like she'll be a lot smoother.

So, is the idle issue most likely remedied by retuning the a/f mix? Or is there another issue at hand?

I'll be checking for vac leaks tomorrow just in case.

I also dont know if this switch has fixed the oil in the carb issue, but we'll find out tomorrow and i'll update.

Thanks for the replys
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Old 06-23-2012, 12:16 AM
 
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