Breather ? - Team Camaro Tech
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post #1 of 14 (permalink) Old Dec 19th, 99, 11:56 AM Thread Starter
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I'm driving a '67 rs/ss, 350 v8. I'm wondering re: "breathers" on my Mickey Thompson valve covers-(about 1 1/2" x 5" stack on the cover that says Offenhauser).
What is the purpose of these? Also, should I be getting oil coming out? (VERY slight amount). I'm obviously a newby owner just trying to get up to speed on engines.

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post #2 of 14 (permalink) Old Dec 19th, 99, 06:34 PM
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These breathers let the excess gas or pressure to escape from the engine. If you are seeing an excess of oil or (blow-by) it could be time for rings. Your SS should have a chrome oil tube in front of the intake with a breather cap and a PVC valve. Be sure that the valve is not clogged or dirty.
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post #3 of 14 (permalink) Old Dec 19th, 99, 07:37 PM Thread Starter
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camaroguy, Doubt that my 350 is stock- have breathers on both valve covers- PCV valve has been moved to passenger side cover, encorporated into the oil filler cap.
Valve appears to be clear- would I be correct in assuming it's time for a compression check and a leak down test?
I would still like to know how "normal" engines without breathers expell these enternal gases. Most covers I see do not have breathers. Thank you for your reply.
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post #4 of 14 (permalink) Old Dec 20th, 99, 06:15 AM
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My Old feeble and sometimes wise opinion : Alot of aftermarket hot-rod valve covers are not baffled below the area that you install an oil cap/ and or p.c.v. valve. If this is the case, they will always puke oil around the breathers as at r.p.m.'s, oil is flying everywhere in the engine. If I were you, I'd pull a breather off and see if there is a baffle in the cover or anything in the breather to diffuse the oil. Good old GM stock covers have very nice baffles in their covers. A "normal or stock" engine expells these gasses through the p.c.v. valve, and back to the intake manifold. They all have a fresh air intake and a way of exhausting the gasses. Before there were p.c.v. valves, they had road draft tubes on the back or side of the engine, depending on make, size and type of engine 6, or 8 cyl. etc. Hope this helps? Rick
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post #5 of 14 (permalink) Old Dec 21st, 99, 11:57 AM
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It looks like everyone has about half the answers. All engines have blowby, a lot is bad...
The PCV should be plumbed into full vacuam, normally in the rear center of the carb. The valve cover that hes the PCV should not have a breather -- plug it.
Fresh air should enter the engine thru the breather in one valve cover, blowby should exit through the PCV valve in the other valve cover into the carb and mainfold to be burned.

With a breather in the same valve cover as the PCV, you're not getting enough negative pressure in the crankcase to suck the blowby out. If the other breather weeps oil once this is corrected, you have too much blowby, ie, bad rings. Definitely make sure the holes in the valve covers are baffled, if you can see rocker arms thru the holes, it'll always be messy. You can make baffles out of sheet metal and epoxy if you have too.



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post #6 of 14 (permalink) Old Dec 21st, 99, 12:14 PM
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I guess I only have 1/2 the answers as I'm kinda messed up from owning those horizontally opposed 6 cyl . Chevrolets, that the only holes in the valve covers are for bolting them on with. LOL ) I really like stock Chevy valve covers also. My 427 will be wearing 1 of 4 pairs of factory hi-perf. chrome dripper covers that I have.
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post #7 of 14 (permalink) Old Dec 21st, 99, 04:43 PM Thread Starter
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Fellows, I'm loven' and learning..thanks for the replies. Jim, I will plug that passenger side breather as soon as time allows, and see if that makes a difference(that will leave just the PCV on that side-PCV appears to be plumbed correctly to the carb). Yenko, I'll also check for baffles.


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post #8 of 14 (permalink) Old Dec 21st, 99, 05:25 PM Thread Starter
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Afterthought, What would happen, performance-wise, if I removed the
PCV and left both breathers open. Would the cooler air in intake increase performance?
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post #9 of 14 (permalink) Old Dec 21st, 99, 06:41 PM
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You should not dis connect P.C.V. systems!You will not have much perfomance gain,if any.It's possable though to create oil leaks from the extra pressure built up in yor crankcase from disconnecting your PCV,your PCV system also helps keep your oil clean longer and helps prevent sludge build up.
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post #10 of 14 (permalink) Old Dec 22nd, 99, 03:30 AM
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The PCV system works on the principal that the breather is on one valve cover, the pcv valve is on the other cover. the valve sucks all of the blow by gases from the crankcase, it uses the engine vacumm to suck, it needs a fresh air supply (breather on opposite valve cover), under wide open throttle, no vacumm, so no suck, at wide open throttle, the engine produces the most blow by, the gases have to go some where, the only place that the gases can escape is the breather, if you drive like i do, it is wide open quite often, a small amount of residue is not a problem, if the engine has several oil leaks or the oil is running from the breather then the engine is due for a serious overhaul.
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post #11 of 14 (permalink) Old Dec 27th, 99, 05:56 AM
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<BLOCKQUOTE>quote:</font><HR>My 427 will be wearing 1 of 4 pairs of factory hi-perf. chrome dripper covers that I have.<HR></BLOCKQUOTE>
What are Chrome Dripper Covers??? If its something to brag about it better be good and I want to know why

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post #12 of 14 (permalink) Old Dec 27th, 99, 08:21 AM
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Buddy&gt; Chrome dripper covers are what would have came from the factory on your '70 Chevelle SS IF it were originally an L78 or LS6 car. Brag? Well, if you had an L78 or LS6 I guess you would be entitled to brag. Go and see clill's '69 Camaro L78 Convert. at eBay. See those nice looking factory chrome covers? That is ONE nice L78 and I'd brag about it also.
http://cgi.ebay.com/aw-cgi/eBayISAPI...item=225668704
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post #13 of 14 (permalink) Old Dec 27th, 99, 08:49 AM
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I believe the term "dripper" came from pulling a valve cover off right after the motor was shut off and the inside of the cover was dripping with oil! <BLOCKQUOTE>quote:</font><HR>Originally posted by Buddy:
What are Chrome Dripper Covers??? If its something to brag about it better be good and I want to know why
<HR></BLOCKQUOTE> The brag part is how we feed our egos... YenkoYS100 is correct clill's car is SWEET and if mine I would be bragging about more than the valve covers!!!



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post #14 of 14 (permalink) Old Dec 27th, 99, 01:41 PM
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Thanks for all the replies. I dont mean to insult anyone its just I am new to Classic Cars' engine terms and uses. Also are they supposed to be performance enhancer covers? Are they tall or something?? While were asking questions what is an RV cam??? heheh thanks
btw: my ss does not have original engine so I wouldn't know See for yourself http://ss396.8m.com
look under engine topic

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want 69 z28 BADLY http://ss396.8m.com


[This message has been edited by Buddy (edited 12-27-1999).]
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