How much venting for gx390

KLUETCH

New member
I have a mild gx390... Stock bore, stock rod and piston, 360 cam, hd valve springs, and a hl380...how much venting does it need? Its my first big block...
 

2kdime

New member
I'll jump in

Do most people tie all the vents into the valve cover and then run a pcv valve to the catch can?

Do you tie the crankcase vents into the valve cover as well? Doesn't that just make a closed loop?

Or what about no pcv valve at all and just open venting?
 

Kart43

Member
I'll jump in

Do most people tie all the vents into the valve cover and then run a pcv valve to the catch can?

Do you tie the crankcase vents into the valve cover as well?[/] Doesn't that just make a closed loop?

Or what about no pcv valve at all and just open venting?


The only vents you are dealing with are crankcase vents, I have seen several people show closed loops, I see no sense in it. If you tie into the valve cover it is a one way valve so an additional valve would not be needed. I don't see any reason to inclde a pcv valve in any of your vents, it is included on modern engines to allow crankcase gasses to flow to the intake to be reburned but it stops gasses from being drawn from the intake to the crankcase. We are not tied into the intake anymore.
 

2kdime

New member
Roger that

I'm running the Parsons valve cover and the way it's set up is the pcv valve inside lets pressure out from under the cover out the 2 vents.

But if I run my crankcase vent to one of those valve cover ports, it's behind the pcv and is essentially an open vent if that makes sense

So I thought to just take the valve cover pcv out and tie the case into the cover and then run a single pcv between the cover and my catch can.

Or run the valve cover pcv and add one to the case and take it straight to the catch can.

You get all that? Hahahaha
 
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