PCV Valve Fouling my plugs and Bad Idle Quality - Page 2 - Chevelle Tech
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post #16 of 91 (permalink) Old Aug 20th, 16, 7:11 PM Thread Starter
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Quote:
Originally Posted by Bonkerman View Post
Is this the same engine with the scuffed cylinder walls?
Yes it is, I reverted back to just running breathers and the situation is much better. Plugs are dry, oil on cylinders has burnt off.

Perhaps the marks was sludge on the cylinder walls. I deleted the last thread, was going south. I just want to know what's going on that's all. I'm not an expert.
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post #17 of 91 (permalink) Old Aug 20th, 16, 7:42 PM
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Re: PCV Valve Fouling my plugs and Bad Idle Quality

Your breather problems and scuffed cylinder walls could be related. You said at the beginning of the thread you had oil leaks and no pcv. Were you getting any blow by? In your other thread you said you found scuffs in the cylinders. Were you looking for the cause of the blow by and that is why you did the bore scope on the cylinder walls? Did you do a leak down test to see if you have compression going past the rings? If you have taken out the pcv and went back to just breathers there is a good chance your leaks might re-appear.
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post #18 of 91 (permalink) Old Aug 20th, 16, 8:24 PM Thread Starter
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Re: PCV Valve Fouling my plugs and Bad Idle Quality

Quote:
Originally Posted by Bonkerman View Post
Your breather problems and scuffed cylinder walls could be related. You said at the beginning of the thread you had oil leaks and no pcv. Were you getting any blow by? In your other thread you said you found scuffs in the cylinders. Were you looking for the cause of the blow by and that is why you did the bore scope on the cylinder walls? Did you do a leak down test to see if you have compression going past the rings? If you have taken out the pcv and went back to just breathers there is a good chance your leaks might re-appear.
Yes that is correct, well i had seepage around the oil pan gasket and the front and rear seals. I am getting steady blowby now. Honestly I have seen scoring just from degreeing the cam on a stand so I am always curious how the break in is developing so I peek in every now and then. I have not done a leak down test, The seepage has already returned. I purchased some PCV valves (LS6 454/425hp versions) but just havent ran them yet.

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post #19 of 91 (permalink) Old Aug 20th, 16, 8:30 PM
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Re: PCV Valve Fouling my plugs and Bad Idle Quality

I think you need to do a leak down test. It will tell you if you are getting pressure in the crankcase. Start there.
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post #20 of 91 (permalink) Old Aug 21st, 16, 1:53 AM
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Re: PCV Valve Fouling my plugs and Bad Idle Quality

If you have enough crankcase pressure to cause leaks with breathers, you've got serious blow by.

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post #21 of 91 (permalink) Old Aug 21st, 16, 9:47 AM
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Re: PCV Valve Fouling my plugs and Bad Idle Quality

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Originally Posted by SHINER View Post
So recently, I have had some oil leaks etc. The reason I believe I was having these oil leaks was because I was only running a breather on each valve cover.

I decided to try a breather on one and a PCV on the other. I no longer am having oil leaks (good). However I am experiencing the following:

- Plugs are now all the sudden fouling out (they used to be nice and tan)
- I am having hard startups (used to just start right up)
- I am having white heavy “burn your eyes” smoke at start (never had that before)
- Idle speed and mixture screws are not quite as responsive anymore

So I started doing some research on transition slots etc (AGAIN…for the millionth time). However, I thought about it and realized I didn’t have this issue until I introduced the PCV valve to the system. The PCV valve I have is one of those Chinese Ebay ones that look like a chrome breather but are just a PCV valve. So the more I read into the PCV, I understand there are actual “tuneable” versions of the PCV valve out there ($$). I thought to myself, why the hell would you need something like that, it’s just a PCV valve. So the more I read, the more I now know about internal springs, etc.

So this is what I think is going on with my car:
I think the piece of junk I purchased has a crappy spring inside and is pretty much open at idle, cruise, WOT, etc.
At idle it is sucking whatever air the crank case has in it and is imposing a false “atmosphere” per say. This means it is not getting its air from the carb (or may be getting some air). This would explain a lazy idle speed screw and mixture screws. However, I need to know what kind of PCV I can buy off the shelf that would handle my motor. I am pulling about 8 inches of vaccum with a bigger roller cam.

My cam specs are:
(@.050) 233/240 .583/.550 108 LSA 104 ICL (I dont think the cam will make that much vacuum)
Timing is 34* Locked Out
Can't tell you what PCV to run but they are definitely not all calibrated the same....my circle track engine's cam probably makes alot less vacuum. Most guys run open breathers with a catch can in this environment. There might be nothing wrong with your engine.
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post #22 of 91 (permalink) Old Aug 21st, 16, 11:07 AM Thread Starter
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Re: PCV Valve Fouling my plugs and Bad Idle Quality

Im thinking about getting one of these with a catch can:

Dual Flow Adjustable PCV Valve | M/E Wagner Performance Products
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post #23 of 91 (permalink) Old Aug 21st, 16, 11:14 AM
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Re: PCV Valve Fouling my plugs and Bad Idle Quality

I have not see any advertised based on calibration. I dont know about that. They are usually advertised as the part stores based on sbc and bbc and the same for JEGS and Summit.

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post #24 of 91 (permalink) Old Aug 21st, 16, 11:20 AM
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Re: PCV Valve Fouling my plugs and Bad Idle Quality

Quote:
Originally Posted by SHINER View Post
Im thinking about getting one of these with a catch can:

Dual Flow Adjustable PCV Valve | M/E Wagner Performance Products
Does it fit in a normal size PCV hole? Looks like a good piece, first I have seen one of those.

67 chevelle malibu / SS/ custom

Currently undergoing a metal work to remove all rust, if I ever get there.

Cant decide on prostreet or cruiser with a 4 speed.
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post #25 of 91 (permalink) Old Aug 21st, 16, 4:14 PM Thread Starter
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Re: PCV Valve Fouling my plugs and Bad Idle Quality

I don't understand the purpose of a PCV when people could just run breathers. Why are they so important?

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post #26 of 91 (permalink) Old Aug 21st, 16, 4:25 PM
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Re: PCV Valve Fouling my plugs and Bad Idle Quality

I think you need to find the source of the problem instead of a way to cover it up. The pcv valve does serve a purpose but you may have other issues that a pcv can't fix only mask the problem. You say you have blow by and you need to find out why. That fancy adjustable valve will only work for so long till the problem gets worse. Leak down test. You may be doing harm by putting it off.
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post #27 of 91 (permalink) Old Aug 21st, 16, 4:47 PM
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Re: PCV Valve Fouling my plugs and Bad Idle Quality

Quote:
Originally Posted by SHINER View Post
I don't understand the purpose of a PCV when people could just run breathers. Why are they so important?
-Copied from another source:
With double breathers you are only allowing "blow by" to escape.
With a PCV (connect to proper vacuum source) you're actually using vacuum to assist in sucking fresh air in thru the opposite breather, flushing the crankcase of the bad combustion by-products. Over time these by-products can build up and can corrosion & sludge.

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post #28 of 91 (permalink) Old Aug 21st, 16, 5:09 PM Thread Starter
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Re: PCV Valve Fouling my plugs and Bad Idle Quality

Quote:
Originally Posted by Bonkerman View Post
I think you need to find the source of the problem instead of a way to cover it up. The pcv valve does serve a purpose but you may have other issues that a pcv can't fix only mask the problem. You say you have blow by and you need to find out why. That fancy adjustable valve will only work for so long till the problem gets worse. Leak down test. You may be doing harm by putting it off.
Well the engine is pretty fresh still so I'm not sure if I'm gonna get blow by still untill the rings sit and wear in

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post #29 of 91 (permalink) Old Aug 21st, 16, 5:30 PM Thread Starter
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Re: PCV Valve Fouling my plugs and Bad Idle Quality

Quote:
Originally Posted by guitargeak99 View Post
-Copied from another source:
With double breathers you are only allowing "blow by" to escape.
With a PCV (connect to proper vacuum source) you're actually using vacuum to assist in sucking fresh air in thru the opposite breather, flushing the crankcase of the bad combustion by-products. Over time these by-products can build up and can corrosion & sludge.
Thanks but why does a PCV have so much influence on idle and drivability?

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post #30 of 91 (permalink) Old Aug 21st, 16, 5:30 PM
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Re: PCV Valve Fouling my plugs and Bad Idle Quality

So you are going to roll the dice?
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