If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Dual PCVs On Chev 350?
I have a pair of nice cast aluminum valve covers for the '74 Chev
truck 350 in my street rod. Both have identical PCV holes so the valve can be placed on either side depending on application. On mine, the driver side has a rubber grommet for the valve and the passenger side has a rubber plug. Both parts are too deteriorated to use. Problem is, my local Chevy dealer can order the grommet but they have no listing for the plug. I've looked for an after-market plug but I haven't found one that fits. I really want to use the covers so I'm thinking of putting a grommet and valve in each side and connecting them to the intake with a "T" fitting. Is there any reason I should NOT do this? |
Ads |
#2
|
|||
|
|||
> wrote in message oups.com... >I have a pair of nice cast aluminum valve covers for the '74 Chev > truck 350 in my street rod. Both have identical PCV holes so the valve > can be placed on either side depending on application. On mine, the > driver side has a rubber grommet for the valve and the passenger side > has a rubber plug. Both parts are too deteriorated to use. Problem > is, my local Chevy dealer can order the grommet but they have no > listing for the plug. I've looked for an after-market plug but I > haven't found one that fits. I really want to use the covers so I'm > thinking of putting a grommet and valve in each side and connecting > them to the intake with a "T" fitting. Is there any reason I > should NOT do this? > Yes, A PCV system has to draw fresh air into the crankcase somehow. The traditional arraignment is to use a PCV valve on one side and a Breather / intake filter on the other to provide the clean air supply. Two vacuum sources leave no way to introduce the fresh air. -- Alan Gallacher Born to Tinker! |
#4
|
|||
|
|||
There is a new 'help' brand of misc. junk parts at most auto parts
stores now, They have all the different types of PCV grommets. Or you could just get a PCV grommet and put a short fat stainless bolt in the hole to block flow and likely look good too... Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's wrote: > > I have a pair of nice cast aluminum valve covers for the '74 Chev > truck 350 in my street rod. Both have identical PCV holes so the valve > can be placed on either side depending on application. On mine, the > driver side has a rubber grommet for the valve and the passenger side > has a rubber plug. Both parts are too deteriorated to use. Problem > is, my local Chevy dealer can order the grommet but they have no > listing for the plug. I've looked for an after-market plug but I > haven't found one that fits. I really want to use the covers so I'm > thinking of putting a grommet and valve in each side and connecting > them to the intake with a "T" fitting. Is there any reason I > should NOT do this? |
#5
|
|||
|
|||
> wrote in message oups.com... > I have a pair of nice cast aluminum valve covers for the '74 Chev > truck 350 in my street rod. Both have identical PCV holes so the valve > can be placed on either side depending on application. On mine, the > driver side has a rubber grommet for the valve and the passenger side > has a rubber plug. Both parts are too deteriorated to use. Problem > is, my local Chevy dealer can order the grommet but they have no > listing for the plug. I've looked for an after-market plug but I > haven't found one that fits. I really want to use the covers so I'm > thinking of putting a grommet and valve in each side and connecting > them to the intake with a "T" fitting. Is there any reason I > should NOT do this? > Anumber1 has it right. The original air cleaner had a hose going from the valve cover to the air cleaner providing filtered air to the crankcase. If you are using an aftermarket air cleaner with no provision for crankcase ventilation, go to Summit or similar and get a grommet and filter that will plug into it. Do not just plug the hole. H |
#6
|
|||
|
|||
What you folks say makes sense but here's the part I don't understand
(sorry - didn't give complete info in my first post): Aside from the PCV holes, the only other hole is the oil fill in the passenger side. The cap, which sure looks like OEM, is the screw-in, NON-breather type - in fact, it has the rubber gasket to seal it to the cover. The covers and cap were on the car when I got it - took them off to clean them up and found the rubber parts are toast. Anyway, it seems to run OK. Although...it sometimes dies on cold start and it idles a little high - maybe to compensate for lean mixture? And, I've had trouble with oil leaks - maybe vacuum breaking the gasket seal? I was looking for a plug in the auto parts stores but I just remembered the local hardware store has some polyethelene button plugs that might work. Sounds like I also may be looking for a breather cap for the oil fill. wrote: > I have a pair of nice cast aluminum valve covers for the '74 Chev > truck 350 in my street rod. Both have identical PCV holes so the valve > can be placed on either side depending on application. On mine, the > driver side has a rubber grommet for the valve and the passenger side > has a rubber plug. Both parts are too deteriorated to use. Problem > is, my local Chevy dealer can order the grommet but they have no > listing for the plug. I've looked for an after-market plug but I > haven't found one that fits. I really want to use the covers so I'm > thinking of putting a grommet and valve in each side and connecting > them to the intake with a "T" fitting. Is there any reason I > should NOT do this? |
#7
|
|||
|
|||
You don't have the correct air filter on it right?
Therefore you have no PCV intake into the engine. This can cause oil leaks. Sometimes the system builds up more pressure than the PCV can suck off and normally this pressure is just vented back into the air filter. Now, it vents out an oil seal... The PCV system needs to be balanced with an air intake matching or better said tuned to the PCV suction. Very likely you can get a filler cap with the vent in it for a 350. If you have a bad air filter, you also will have issues with the carb freezing up because you also no longer have the heat pipe to the intake. This can happen in high humidity at above freezing or even turn it into one solid block of ice on the highway. It's 'not' fun realizing the gas pedal is stuck at 55 mph in a snowstorm..... You also can't pass emissions in most places with a defective PCV and no hot air intake to the carb. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's wrote: > > What you folks say makes sense but here's the part I don't understand > (sorry - didn't give complete info in my first post): > > Aside from the PCV holes, the only other hole is the oil fill in the > passenger side. The cap, which sure looks like OEM, is the screw-in, > NON-breather type - in fact, it has the rubber gasket to seal it to the > cover. The covers and cap were on the car when I got it - took them > off to clean them up and found the rubber parts are toast. Anyway, it > seems to run OK. > > Although...it sometimes dies on cold start and it idles a little high - > maybe to compensate for lean mixture? And, I've had trouble with oil > leaks - maybe vacuum breaking the gasket seal? > > I was looking for a plug in the auto parts stores but I just remembered > the local hardware store has some polyethelene button plugs that might > work. Sounds like I also may be looking for a breather cap for the oil > fill. > > wrote: > > I have a pair of nice cast aluminum valve covers for the '74 Chev > > truck 350 in my street rod. Both have identical PCV holes so the valve > > can be placed on either side depending on application. On mine, the > > driver side has a rubber grommet for the valve and the passenger side > > has a rubber plug. Both parts are too deteriorated to use. Problem > > is, my local Chevy dealer can order the grommet but they have no > > listing for the plug. I've looked for an after-market plug but I > > haven't found one that fits. I really want to use the covers so I'm > > thinking of putting a grommet and valve in each side and connecting > > them to the intake with a "T" fitting. Is there any reason I > > should NOT do this? |
#8
|
|||
|
|||
On Thu, 2 Jun 2005 wrote:
> Aside from the PCV holes, the only other hole is the oil fill in the > passenger side. The cap, which sure looks like OEM, is the screw-in, > NON-breather type - in fact, it has the rubber gasket to seal it to the > cover. Because in most post-'66 applications, the one grommet contains a PCV valve and the other contains an elbow connected to a hose connected to crankcase inlet air filter installed in the air cleaner assembly with the hose fitting protruding outward through the air cleaner's sidewall. > Although...it sometimes dies on cold start and it idles a little high - > maybe to compensate for lean mixture? And, I've had trouble with oil > leaks - maybe vacuum breaking the gasket seal? Could well be...note that if your engine's whipped, even two PCV valves won't keep up with the blowby volume and the crankcase pressure will force the gaskets *out*. > I was looking for a plug in the auto parts stores but I just remembered > the local hardware store has some polyethelene button plugs that might > work. Or see my previous post, www.caplugs.com . > Sounds like I also may be looking for a breather cap for the oil fill. Yep. They're available with a self-contained filter mesh and external breathing, with the same twist-in base as your present flat cap. Don't have my Stant catalogue in front of me or I'd give you a number. DS |
#9
|
|||
|
|||
OK, the pieces are falling into place thanks to you folks' help. Again
I apologize for giving less than complete info - should've realized all this stuff is interrelated. If I've got the numbers decoded correctly, the engine is a '74 Chev truck 350. It's in a '38 Plymouth coupe that probably weighs under 3K lbs. Supposedly the engine has about 50K miles. It doesn't burn oil, maintains a consistent 190 temp and, aside from the aforementioned starting/idle problems (which don't seem that serious), runs good. It's stock except for Mallory ignition, Edelbrock manifold, Holley 570 cfm 4-bbl, and dual exhaust on OEM ram-horn manifolds. It's hooked to a 350 auto with shift kit and a Nova rear - haven't checked the ratio but I expect it's in the 3.00 - 3.50 range. The air cleaner is after-market - basically a 9-inch round filter sandwiched between top and bottom plates. Carb freezing shouldn't be problem as I don't drive the car in cold weather and certainly not in snowstorms. For better or worse, we don't have emissions testing around here. Apparently the PCV grommet and the oil cap are OEM. From the construction and fit of the plug, I assumed it is as well. But it doesn't have a part number like the PCV grommet and the Chevy parts guy couldn't find a listing for it. So now I'm thinking somebody blocked the breather hole with an after-market plug when the OEM manifold/carb/air cleaner were replaced. At this point the simplest solution appears to be replacing the PCV grommet and oil cap with OEM and replacing the plug with an after-market grommet and push-in breather - all those parts should be available. Thanks again for everyone's help in working this out. |
#10
|
|||
|
|||
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Single Bulb to Dual Bulb | Andy | VW water cooled | 9 | May 28th 05 08:52 AM |
Single Bulb to Dual Bulb | [email protected] | VW air cooled | 3 | May 25th 05 03:21 PM |
FS: 35 Chev Master 2dr Street Rod | Ron | General | 0 | July 2nd 04 06:01 PM |
Dual Rear Wheel, 4X4 & Snow Chains | OrygunGuy | 4x4 | 0 | December 22nd 03 04:05 PM |