hartsmike

Just a general question I have. I've noticed that on the passenger side of the valve cover there is a hose coming off the valve cover that is suppose to go into the carb. I would guess it is to burn off fumes. On some of the "hot rod" type motors that doesn't exist. I'm in the process of a build with vortec heads and am wondering if I will need valve covers for this. It is going to be with a quadrajet if that makes any difference.

Thanks

sofakingdom

iTrader: (1)

It's the "makeup" air for the PCV system.

The PCV valve is in the left valve cover; the valve goes there, and meters some of the crankcase contents into the intake, being sucked there by engine vacuum. Obviously fresh air has to come back into the crankcase to replace that which is sucked out. Equally obviously this wants to be clean and filtered air. That's what that hose does. In a stock carb setup there's a little foam filter mounted in the air cleaner that it plugs onto.

The purpose of the PCV system is to keep stale combustion by-products and whatnot from accumulating in the crankcase and sludging it up and poisoning the oil. So yes you want to keep it no matter what fuel delivery system you use.

Stock 87-up VCs have the fittings for it all.

MoJoe

iTrader: (5)

That is part of the PCV = Positive Crankcase Ventilation. It sucks out gasoline/combustion gasses that slip past the rings, draws fresh air through the engine to pull out any moisture (vaporized once the oil gets warm) that gets in and otherwise would foam/sludge the oil and corrode metal.

Without it, the combustion pressure that leaks past the rings will cause a positive pressure and start pushing oil out wherever it can... oil leaks.

Keep it.

hartsmike

Thanks for the info guys.. Next question is will the factory valve covers off the vortec heads work? I'm going carb set up.

sofakingdom

iTrader: (1)

Yup.

Neither the carb nor the VCs have excessive modesty... they'll keep almost ANY company.

vinny R

I have a question on this, can I remove the vacuum hose from the PCV valve? I want to run 2 breathers, one will filter the air in and the other to attach to a PCV valve to filter the crankcase gas out. Do you need the vacuum? I have a TPI set up and want to keep the crankcase gases out of the engine, No emissions here.

Night rider327

iTrader: (13)

You really need the PVC valve hooked to a vac source and then a clean air source.

I run a PVC valve in one valve cover with a hose/line to the carb, then an open filter type breather in the other valve cover. I do this with all of my engines, be it 200 HP or 500 HP

hartsmike

Nice set up there!

Night rider327

iTrader: (13)

Thanks man. Its been a long ways in the making for sure.

355, 10.34:1, Wisco pro tru pistons, scat crank and rods.
7 qt oil pan, windage screen, rear main baffle, ARP main studs
Brodix IK 200cc heads.
Howards solid flat tappet 249/252@.050", 106 lsa, .570"/.579" lift
Howards 1.6 full roller billet rockers
7/16" rocker studs
Edelbrock performer RPM intake with divider wall milled 2x1" and port matched.
Holley 4150 HP 750 cfm double bumper
Carter 172 gph mech speedway fuel pump
Alum. underdrive pulleys

Th-400, 3500 stall 9.5" converter
Moser ford 9" housing and 31 spline axles, ford iron case third member, detriot locker, motive 3.89 gear set

vinny R

I am running the same setup, just flopped on the sides. I like the way the breathers look so I wanted to duplicate that on the other side but I will keep it the way it is.

sofakingdom

iTrader: (1)

Vinny, I'm surprised your rockers don't hit your VCs, with the VCs backwards like that.

vinny R

Me Too!

sofakingdom

iTrader: (1)

Yeah, the intake side of the VC stands up kinda straight, and the exhaust side kinda is more at an angle; when they're backwards, the push rod end of the rockers (which is on the int side of the heads) often scrapes against the VC because the "leaned in" exh side doesn't clear them. Butt hay... if it works, it works.

eseibel67

Really? I thought they were symmetrical. In fact I was planning on flipping the driver's side cover north-south just to reduce the distance I have to stretch for the oil fill. Guess I'll just leave it.




I learn something new on every one of my 17,000+ days. Should be wiser than I am by now.

vinny R

I can't speak for the previous 7 owners but that is the way it was when I bought it and it works just fine, no noise. The PCV valve lines up to the vacuum ports the way it sits.

TTOP350

iTrader: (8)

Center bolt VCs don't work like that.
In 90 GM changed the locations of things on the covers.
Driver side, the oil fill went to the front and the PCV went to the rear.
On the Pass side, the pcv fresh air hose went from the rear to the front.