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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: hobbz on December 05, 2013, 06:39:26 am

Title: What went here (hole on valve cover)
Post by: hobbz on December 05, 2013, 06:39:26 am

The rear hole on the drivers side valve cover... What went there? When I bought it, it had a spark plug shoved in it to seal it off. The hole isn't big enough for a standard 1 1/4 breather filter. Is it just that the stock breather filter wasn't that big, or did something else go there? 

(http://www.hobbz-garage.com/gallery/d/9019-2/r10-06.jpg)

Title: Re: What went here (hole on valve cover)
Post by: rich weyand on December 05, 2013, 08:01:10 am

Depending on the year, most likely a PCV (positive crankcase ventilation) valve.  This is a little widget that connects to a vacuum port on the carb.  When the engine runs, a certain amount of exhaust gases make it past the rings into the crankcase.  The PCV valve lets those gases be sucked back into the engine.  It's a valve because it is made to keep the carb from sucking oil.

Without crankcase ventilation, the gases condense into sludge in the oil, so it's worth putting one on.

Title: Re: What went here (hole on valve cover)
Post by: Captkaos on December 05, 2013, 08:03:31 am

It is a hose that goes to the one missing coming out of the ring around the top of the throttle body.
The PCV valve is at the front of the passenger side valve cover.

Title: Re: What went here (hole on valve cover)
Post by: bd on December 05, 2013, 08:31:06 am

Quote from: Captkaos on December 05, 2013, 08:03:31 am

It is a hose that goes to the one missing coming out of the ring around the top of the throttle body.
The PCV valve is at the front of the passenger side valve cover.

X2

The original "vent hose" was a molded plastic pipe.

Title: Re: What went here (hole on valve cover)
Post by: hobbz on December 05, 2013, 10:30:00 am

Thanks guys. I will try to find a breather filter that fits it.

Title: Re: What went here (hole on valve cover)
Post by: rich weyand on December 05, 2013, 10:58:50 am

Quote from: Captkaos on December 05, 2013, 08:03:31 am

It is a hose that goes to the one missing coming out of the ring around the top of the throttle body.
The PCV valve is at the front of the passenger side valve cover.

Urp.  Right you are.  Didn't see it.  I have a PCV on one side, and a breather cap on the other, to get ventilation across the crankcase.  But I only have one hole in each valve cover.

Title: Re: What went here (hole on valve cover)
Post by: bd on December 05, 2013, 12:33:22 pm

Quote from: hobbz on December 05, 2013, 10:30:00 am

Thanks guys. I will try to find a breather filter that fits it.

Just plumb it to the existing steel nipple that exits the back of the spacer ring sandwiched between the TBI base and air cleaner assembly.  That's where it goes.

Title: Re: What went here (hole on valve cover)
Post by: hobbz on December 05, 2013, 12:51:07 pm

there isn't a spacer ring, the air filter sits directly on top the throttle body. I stopped at Autozone and found one the would work for now until I put a 350 in it.

Title: Re: What went here (hole on valve cover)
Post by: bd on December 05, 2013, 12:59:45 pm

What happened to the 'ring' in your image?

Title: Re: What went here (hole on valve cover)
Post by: hobbz on December 05, 2013, 01:08:00 pm

lol. oops, i guess it does have one. I don't think it has a hole in it.  I will have to go check.

Title: Re: What went here (hole on valve cover)
Post by: Captkaos on December 05, 2013, 02:44:48 pm

It has a large hose at the back.  Look at this picture.

Chris Lucas
73-87chevytrucks.com
captkaoscustoms.com
squarebody.biz

Title: Re: What went here (hole on valve cover)
Post by: hobbz on December 05, 2013, 02:48:02 pm

Thanks, I found it when I went back up to the garage.