I've got new valve covers with vent holes and grommets sized for breathers. I went to Autozone and found a larger gromment that will fit the VC and has a small enough hole to fit my PCV valve as well. Unfortunately the grommet isn't angled to take into acct. the VC angle like the original grommets are. But I did however see some PCV valves at AutoZone that had the hose connector angled down on the PCV and was wondering if I could grab one of those PCV's instead of the exact PCV part specified for my Z??? Not sure if PCV's are pretty much the same on the inside (if they're the same diameter......or do PCV's have different internals rated for different engines?

Thanks,
- Joel

 

In my limited research on PCV valves I have found them to be different. The internal plunger weight and the orifice size's vary. These two pieces control the volume of airflow and the vacuum depression wthin the crankcase.

RBob.

 

Ahhh....that's what I figured....thanks for the verification. I'm curious how these PCV's are rated for the particular engines. I mean the PCV I bought is for my stock L98 350....but now it's stroked to a 383 with a MR and everything is different, so is the stock PCV sufficient??

Makes me wonder.....

Thanks,
- Joel

 

The pintle springs are also calibrated. I used to work for a supplier to Robershaw, and the pintles had to both meet dimensional specs and flow tests. They were so critical, Robershaw provided a flow bench, tooling, and calibrated springs for vvarious applications to assure quality control of just the measured pintle flow. That was all SPC data, as well as dimensional and mass SPC charting that went to the customer with the product.

Don't just throw any old PCV valve on there.

 

So what kind and how do you decide?

 

Yeah you really have me thinking now Vader....is the stock replacement PCV valve for a 350 going to be sufficient for my new 383 (sig. below) or should I be looking into a larger one that's better suited??? I heard the PCV would be the way to go vs. std. breather valves...so I'd prefer to stay with PCV.

Thanks,
- Joel

 

Yeah, the're all a little different, but if you stick with a V8 small block chevy application you'll be fine. Stroking it out to 383 isn't going to make much difference at all in PCV requirements. The amount of air that flows through them is so small relative to what's flowing past the throttle plates it's almost inconsequential.

 

Thank you...that answers my question.....one less thing to worry about on the new engine....

- Joel

 

The biggest prblems occur with a longer duration cam profile and the often resultant lower idle vacuum. At lower vacuum, the PCv will flow MORE. You may have to get a valve designed for a smaller displacement engine to correct the flow at lower vacuum. If you are below 14" Hg at idle, this may apply to you.