Original Breather vs PCV?
03-30-2009, 07:55 AM
#21
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As I remember it, the '63-'64, 250/300 hp cars had the restrictor orfice in the carb to draw vacuum on the crankcase instead of the PCV valve as used on the fuelie engines. I don't remember what the SHP carb jobs used but it was one or the other.
AFAIK, NO 1963 model car was sold new in this country with a road draft tube instead of some kind of system that returned crankcase fumes to the air intake of the engine. Somebody had been messing with your '63car before you bought it or your memory is fainling.
Last edited by MikeM; 03-30-2009 at 01:11 PM.
03-30-2009, 01:01 PM
#22
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Yes there is no PCV valve in a 64 327 with 300HP! It is difficult to believe that this car does not have a PCV! The people that rebuilt the engine asked where the PCV valve was and I had to explain that there was a short transition from ropad draft tube to the 63-64 system to the PVC system!
03-30-2009, 01:19 PM
#23
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Development testing at Chevrolet Engineering for the '68 PCV systems (using only the valve covers for the "intake" and "exhaust" side of the system, since the block vent hole and oil fill tube were gone) showed a much higher rate of "oil pullover" through the PCV valve when it was mounted in the passenger side valve cover.
Testing (with clear plastic oil pans) proved that oil thrown off the crank and rods was thrown past and away from the bottom of the oil drainback holes on the driver's side, but was thrown directly up at the bottom of the drainback holes on the passenger side, which caused PCV vacuum to pull much denser oil vapors up through the drainback holes on that side, fouling the PCV valve at low mileage.
That's why the PCV valves were always located in the driver's side valve cover from 1968-up. Locating the "intake" side on the passenger side valve cover didn't matter, as that valve cover wasn't under external vacuum - internal crankcase vacuum pulled fresh air from the air cleaner through it into the crankcase.
03-30-2009, 04:34 PM
#24
Burning Brakes
Thread Starter
Here are a few pics of my intake and John was right on as usual. The back of the carb has a fitting that must the be the metered orfice and the hose goes to the oil filler tube. Since I have this system should I leave it or convert to PCV?
03-30-2009, 05:04 PM
#25
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Your question has already been specifically addressed in posts # 2,3,4,5, 8,16, 21 and 22.
Would it make you feel better if you got the same answer one more time?
Just make sure you have a clean air source going into the back of the block and you're all set. What you have could be a little neater but it'll work. Make sure the oil fill cap has a gasket on it and is sealed tight. Check that orfice elbow and make sure it's not plugged up.
Would it make you feel better if you got the same answer one more time?
Just make sure you have a clean air source going into the back of the block and you're all set. What you have could be a little neater but it'll work. Make sure the oil fill cap has a gasket on it and is sealed tight. Check that orfice elbow and make sure it's not plugged up.
Last edited by MikeM; 03-30-2009 at 05:07 PM.
03-30-2009, 06:03 PM
#26
Burning Brakes
Thread Starter
Thanks for the info! Since I have the engine torn down just wanted to check with the forum to see if I should upgrade to PCV. So based on the input I will leave well enough alone. 
