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  #31 (permalink)  
Old 04-07-2004, 03:16 PM
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On my 350 sb,I have aluminum valve covers on mine ,and i had a problem with the rockers hitting the top side of the valve covers ,but it didnt hit at all times..and when i took the covers off to see were it was hitting ,it was hard to see,so what i did was took a drill bit the next size of the hole and drilled it out ,and when i installed them back on i had to push up alittle on the covers before tighten them down,and the knock was gone. If the valve cover gaskets are old it will be best replacing them because
it will be hard getting them to stay without them trying to go back were it sat before..
Robbie

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  #32 (permalink)  
Old 04-07-2004, 06:23 PM
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You only need a breather on both valve covers if both the following conditions exist; 1.) You're not running one of those old fashioned "Road Draft" crancase vent tubes and 2.) You're not running a PCV valve.

If you're PCV valve and non-vented oil fill cap are in the same valve cover on the same side, then install a breather in the valve cover on the oposing side. This will provide adequate crancase draft and allow you're engine to vent from left to right or right to left, which ever you prefer... Without the "vaccume" ventilation action of a PCV Valve in one side or the other, or the induced draft of a road tube, both covers must be vented to provide natural ventilation where no draft is happening..

You've got three choices here that all work fine. If you got a cam that doesn't let your motor make a whole lot of vaccume, I'd suggest venting both covers - forget the PCV valve.
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Old 04-07-2004, 06:58 PM
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The knocking you were hearing was probably the sound of the covers on the engine popping in and out with the force of the vacuum. You get a very similar sound if your oil pump pickup is too close to the bottom of the pan. Sounds like a spun bearing, or a rod knocking!! I pulled a perfectly good 454 apart because of this.... Took some major head scratching to figure out what was happening as the bearings and rods were perfect.
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  #34 (permalink)  
Old 04-07-2004, 07:28 PM
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Quote:
Originally posted by PrimeMover
You only need a breather on both valve covers if both the following conditions exist; 1.) You're not running one of those old fashioned "Road Draft" crancase vent tubes and 2.) You're not running a PCV valve.

If you're PCV valve and non-vented oil fill cap are in the same valve cover on the same side, then install a breather in the valve cover on the oposing side. This will provide adequate crancase draft and allow you're engine to vent from left to right or right to left, which ever you prefer... Without the "vaccume" ventilation action of a PCV Valve in one side or the other, or the induced draft of a road tube, both covers must be vented to provide natural ventilation where no draft is happening..

You've got three choices here that all work fine. If you got a cam that doesn't let your motor make a whole lot of vaccume, I'd suggest venting both covers - forget the PCV valve.

What is a "road draft crank case vent tube??

My car is running great and I just have a vented oil filler cap and a vented breather on the same valve cover. The other valve cover is sealed though.
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Old 04-07-2004, 07:33 PM
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Quote:
Originally posted by 69elcaminoss
What is a "road draft crank case vent tube??

My car is running great and I just have a vented oil filler cap and a vented breather on the same valve cover. The other valve cover is sealed though.
It's from the ooold days. It was literally a metal tube that ran down the back of the motor to the low pressure area under the car. The forward motion of the car produced the vacuum to ventilate the motor through the stink tube......
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Old 04-08-2004, 06:25 PM
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Redsled - on a fresh motor that isn't being run real hard all the time, I reckon you can get by without a PCV system and a breather vent in just one valve cover. Problem is, most of the fumes, or blow-by caused by combustion are hot and have a tendency to rise till they cool down. Without a breather in both covers, after about 15000 miles, sludge will start to build and collect in the valve cover and on the rocker arms on the non-vented side.

Thanks for describing the road draft tube. Have you ever been into an old road draft motor that's spent it's whole life going back and fourth to the grocery story?? NASTY! I do believe, the Positive Crankcase Ventilation valve is still the best invention since chocolate milk.

Here's what the setup on my 53 looked like shortly after I put it together. I've gone to breathers in both covers now and it runs a lot stronger without the PCV stealing all my vaccume.
http://hotrodders.com/gallery/showph...cat=500&page=4

Last edited by PrimeMover; 04-08-2004 at 06:36 PM.
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Old 04-08-2004, 08:53 PM
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Quote:
Originally posted by PrimeMover
Redsled - on a fresh motor that isn't being run real hard all the time, I reckon you can get by without a PCV system .....
I totally agree. I wasn't trying to give the impression that a pcv was a necessity. I put them on my cars because I don't like the smell of the crankcase fumes while I'm driving.

Nice car by the way.
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