Rusty Bowtie
General Category => GM Tech Questions and Answers => Topic started by: Cool53 on January 03, 2014, 05:23:47 PM
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They are not all the same.
A ache vette in 1976 had a PCV valve that only flowed .7 CFM. Normal Chevy V8's flowed 2.8. The V8 valve placed in a ache vette would not really affect how it ran, but would empty the crankcase in no time. Once they realized they had a problem chevy had the Chevette units plastic T cast with pink plastic to make it stand out. The aftermarket did not.
There are thousands of different PCV valves, many look alike. But they flow differently, open at different throttle amounts, and close differently. Spring rates are different, valve shapes are different, internal passage sizes are different.
For this reason it's better to use a factory (Delco, Ford, Mopars) valve that is close to what yo are running, or even better, a Moroso crankcase pressure control valve. With this valve taking the place of the breather or breather tube and adjusted properly to maintain a crankcase pressure of 5-8" of vacuum, you keep the rings pulled in slightly at cruise, reducing drag, you make valve seals, rear main seals, and front crank seals that may not be all that healthy work a lot better. You now don't really need a PCV because The Moroso part is controlling air flow. These pieces work great. The next step up from that is an all out vacuum pump, but if you aren't racing you don't need that. If you race once in a while you may want to T an aspirator from the header collector in, but make sure to place a check valve, like from an AIR pump into it so the Moroso valve will still work.
Simple things make big differences.
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GOOD STUFF! THANKS
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Hi Ed,
Are you interested in any Tuned Port Parts? I have a bunch of stuff I will probably never use. Jef
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Hi Ed,
Are you interested in any Tuned Port Parts? I have a bunch of stuff I will probably never use. Jef
Let me know you what have, I lean toward to the 90-92 speed density stuff and have a decent collection of TPI parts..both MAF and SD.
Also made a couple of TBI harness's and about to try my 1227747 ECM 24 to 28 pin EPROM conversions for the first time!
Ed
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There's a guy that rebuilds injectors here in Fitchburg, MA, Hurst Fuel Injection. Does a great job, gives you all the before and after numbers. Gets about $125 a set of 8.
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Thanks for that info, I have been manually cleaning my injectors (12v battery & throttle body cleaner). Learned that using one of those laser thermometers on the cylinder exhaust tubes helps to ID bad injectors via temperature along with the ohm meter.
I may need a good source for injector rebuilding in the future. Send me a PM with any TPI parts for sale.
Ed
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Jef
While we're talking about controlling crankcase pressure how about some giving us you insight on the various piston rings that are now available and how they can help or hurt engine performance especially when rebuilding an early engine.
Moose