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Hi everyone. I posted here a while back about the smoking from my 66 mustang that had a fairly recent rebuild. Well, it would smoke on hard acceleration. Someone suggested to try a pcv valve for the year engine that was rebuilt and placed in the car. Original 289 was worn out so I had to use a '79/302 for the rebuild. Well, I had put the old 289 pcv on the '79/302...never would have thought it would make a difference. Well, awhile back I got a pcv for the 302 and today decided to try it out. Well, it worked and the smoke on hard acceleration is no more! :nono: Now maybe someone could 'splain to me why it would make a difference? The valve is smaller than the old one...just curious. :D
 

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I believe the difference is the amount of vacuum needed to open the valve. Different pcv valves open at different vacuum levels. If thats not right I am sure someone will correct me.
ccnova
 

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the 302 might have more vacume than a 289, if both were stock it seems odd, but i had a 84 mustang GT, new. when i bought it it would smoke when you cranked it up in the morning, a old ford man told me to put a 194 thermostat in it, never smoked again at start up, fords are funny like that . WORMY.
 

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The PCV Valve is a controlled metering device (engine manifold vacuum) and is engineered for service in each unique application. It is especially more important to use the correct size valve on later emission controlled cars.

If a valve has too small of an orifice for a particular application, it will not be able to ventilate the crankcase properly. Too large of an orifice and it disrupts the fuel mixture (lean mixture).
 

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Discussion Starter #5
KULTULZ said:
If a valve has too small of an orifice for a particular application, it will not be able to ventilate the crankcase properly. Too large of an orifice and it disrupts the fuel mixture (lean mixture).
So since I changed out the valve, I probably need to go back and make sure I am not running too rich or too lean in the idle/run circuit in my edelbrock 600 cfm... Thanks for the info btw.
 
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