PCV on 8BA

R

Robert Legner

Member
I connected the PCV valve and am doing some testing. Prior to adding the valve the vacuum was running around 18 inches. After putting on the valve the vacuum drops to around 5 inches. The only obvious effect is the RPMs go up slightly. There does not seem to be any other change in the engine operation. My question is what is the real effect in the drop of vacuum? Does it adversely effect the engine in any way. I admit I really do not know much about the vacuum system on an 8BA. Thank you in advance for any comments.
 
I read about others installing a PCV system and swear by it, taking the fumes away. Is there a way to connect the valve without losing vacuum? Does that mean the road draft tube is the best way on those old engines ?
 
Which PCV valve are you using? The best I found is Fram p/n FV306, used on many Toyotas and Lexus's. Much better built than the typical small-block Ford PCV.
 
Robert Legner said:
I read about others installing a PCV system and swear by it, taking the fumes away. Is there a way to connect the valve without losing vacuum? Does that mean the road draft tube is the best way on those old engines ?
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Perhaps you can be more specific as to exactly where you are pulling the vacuum source from and where you are taking the vacuum readings (which are for the most part meaningless)
 
If you are adding air to the intake manifold after the carburetor it will change the a/f ratio (more air added to the mixture) and possibly lean it out. Similar to a vacuum leak. If the carb has power valves, a lower manifold vacuum can be an issue as well.
 
JSeery said:
If you are adding air to the intake manifold after the carburetor it will change the a/f ratio (more air added to the mixture) and possibly lean it out. Similar to a vacuum leak. If the carb has power valves, a lower manifold vacuum can be an issue as well.
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After adding a PCV valve, I did not notice any difference in the A/F ratio readings on my vehicle.
But some time in the future, just for HaHa's I plan to do a test by momentarily dis-connecting and connecting the vacuum source to see if there is any change in the A/F reading.
 
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I'm running a PCV on my 8ba. Valve is for a 231 Buick. Engine is stock with a 94 redone by CharlieNY and a Bubba Chevy mechanical advance distributor. I didn't have to make any adjustments when I installed the PCV set up. Engine runs smooth and strong. No issues since hooking it up.
 
51 MERC-CT said:
After adding a PCV valve, I did not notice any difference in the A/F ratio readings on my vehicle.
But some time in the future, just for HaHa's I plan to do a test by momentarily dis-connecting and connecting the vacuum source to see if there is any change in the A/F reading.
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I would agree, but if the pressure drop is to 5 psi as stated in the OP I would have some concern.
 
My 8BA has a standard Holly 94, I get the vacuum from the windshield wiper port right above the intake manifold. I bought the PCV system from the one recommended on Ford Barn, the vender is Western Chassis. Am I doing something I should not?
 
>>>taking the fumes away>>>


Do it the easy way. Get a Chrysler-style hose-barb oil-filler cap for the fuel-pump stand. Run the 5/8 or 3/4 hose to the air cleaner. Jack E/NJ
 

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Jack E/NJ said:
>>>taking the fumes away>>>


Do it the easy way. Get a Chrysler-style hose-barb oil-filler cap for the fuel-pump stand. Run the 5/8 or 3/4 hose to the air cleaner. Jack E/NJ
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That works for a low level of crankshaft ventilation, but it is not PCV. I'm not a big PCV fan on a flathead myself, so it could be an option, but just to be clear it is not PCV.
 
OK. How about calling it lowercase pcv for passive venting and uppercase PCV Positive Venting? That should clear things up. 8^) Jack E/NJ
 
Jack E/NJ, do you have a part # for the Chrysler hose-barb filler cap? That sounds like what I want to do. I do not like messing with the vacuum.
 
Stant 10070, Mr Gasket 2063, etc. You might have to adjust the center 'whatchacallit' a bit to fit snuggly in your pump stand pipe. Jack E/NJ
 

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Robert Legner said:
I connected the PCV valve and am doing some testing. Prior to adding the valve the vacuum was running around 18 inches. After putting on the valve the vacuum drops to around 5 inches. The only obvious effect is the RPMs go up slightly. There does not seem to be any other change in the engine operation. My question is what is the real effect in the drop of vacuum? Does it adversely effect the engine in any way. I admit I really do not know much about the vacuum system on an 8BA. Thank you in advance for any comments.
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You're doing something wrong, because there should only be a very small (if any) vacuum loss with a correctly plumbed and valved PCV system. A picture or two and valve info would be helpful.

Keep in mind the oil fill on an 8BA is also the crankcase ventilation air intake, which should see max available atmospheric pressure, not possibly reduced pressure resulting from using the Chrysler style cap plumbed to the air cleaner.
 
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