PVC valve question

ClanCassidy · Post by **ClanCassidy** » February 19, 2007, 8:15 pm

Hi,

Just bought a new PVC valve (1970 302 engine). Should the internal poppet be loose ? When I turn the valve over, the poppet opens a little bit. I can push on it and it opens further. Seems like the poppet should have some positive spring force holding it closed in the free state. Then again, I never really looked at one of these things before so I don't know.

Does this part sound ok ?

Thanks.

John.

tomrooster · Post by **tomrooster** » February 19, 2007, 8:32 pm

I beleive it should be loose ,So if you shook it , it would rattle. It shouldn't be positive spring force . Sounds OK. Tom

ICEMAN6166 · Post by **ICEMAN6166** » February 19, 2007, 10:41 pm

it supposed to rattle.

Hoofbeat Racer · Post by **Hoofbeat Racer** » February 20, 2007, 8:33 am

If it's clean, blow through the bottom but you won't be able to blow through the top

bobenhotep · Post by **bobenhotep** » February 24, 2007, 7:53 am

it is supposed to do that. use the highest flowing one you can get away with...

64 f100 · Post by **64 f100** » February 26, 2007, 10:16 am

If it doesn't rattle, then you have a problem.

Rich

Johnny Canuck · Post by **Johnny Canuck** » February 26, 2007, 11:47 am

This brings up a question for me, as I seem to get pressure building up in my 351w's crankcase and blowing oil out.

The PCV valve, (brand new) is on the oil filler cap on the drivers side bank valve cover. It draws directly into the carb base. The return hose is from the air cleaner to the passenger's valve cover. When the engine is running you can HEAR the PCV buzzing, as it opens and closes in rapid succession.

Is this setup wrong? or why am I getting this crankcase pressure buildup, with a new and obviously functioning PCV?

Slick Fan · Post by **Slick Fan** » February 26, 2007, 12:59 pm

Johnny Canuck wrote:This brings up a question for me, as I seem to get pressure building up in my 351w's crankcase and blowing oil out.

The PCV valve, (brand new) is on the oil filler cap on the drivers side bank valve cover. It draws directly into the carb base. The return hose is from the air cleaner to the passenger's valve cover. When the engine is running you can HEAR the PCV buzzing, as it opens and closes in rapid succession.

Is this setup wrong? or why am I getting this crankcase pressure buildup, with a new and obviously functioning PCV?

Is the engine a high mileage engine by chance? I had a 352 that did that & continually got worse. I decided the compression rings were worn out & weren't sealing very well any more. If I took the breather cap off with the engine running, I could actually feel air blowing against my hand, as I held my hand over the hole.

Also, sometimes a PCV can still rattle, but not flow as well as new any more.

Johnny Canuck · Post by **Johnny Canuck** » February 26, 2007, 1:16 pm

I had a head off it last year, as it blew a gasket. It's .030 over and doesn't even have much of a ridge on the top of the piston travel, you can barely catch a fingernail on it. I would say less than 10,000 miles since rebored.
So, I doubt that is the problem. 150-160 lbs compression. I think the PCV system may be hooked up backwards... just my guess. Not sure.

ICEMAN6166 · Post by **ICEMAN6166** » February 26, 2007, 2:11 pm

JC, try it without the return hose and see if it changes anything.
none of our trucks here have a return hose, and im not quite sure why you would need it?