Team Camaro Tech banner
1 - 16 of 16 Posts

·
Registered
Joined
·
230 Posts
Discussion Starter · #1 ·
On drivers side there was a PVC in the valve cover. In the pass side there was a straight tube with a curved hose to the air cleaner. I know I kept the tube but can't find it. Ricks and Classic Ind both sell a curved tube for SBs, but I know original was straight. Anyone seen a straight tube for sale anywhere?

With an after-market open-element air cleaner I had set it up with a PVC in both valve covers with two hoses and a T-fitting to the carb base. Will it vent the crankcase effectively like that?

Thanks, guys.
 

·
Retired
Joined
·
26,944 Posts
My understanding is there was a rounded valve cover elbow used on '69 and newer small blocks and a different elbow used on big blocks that made a hard 90deg corner turn. No straight tube used that I know of.

By design the pcv system sucks vapors in the crankcase out through the vacuum connected pcv valve and fresh air is pulled into the crankcase through the tube connected to the base of the air cleaner. Using 2 pcv valves and connecting vacuum to both disables the system.
 

·
Registered
Joined
·
230 Posts
Discussion Starter · #3 ·
Thanks Dennis. Still not sure about the tube. I'm pretty sure it was straight with a curved hose. On the PVC question—I left out the fact that I have a breather tube in the front of the intake (not original, I know.) Would it work OK that way?
 

·
Retired
Joined
·
26,944 Posts
Ken, there's a lot of info floating around about there being a directional flow to support the factory putting the PCV valve in the drivers valve cover and not the passanger side. I have heard from some very qualified mechanic's that it doesn't matter Early on some factory usage pulled it from the breather tube or a vent tube at the back of the block.

In your case if fresh air could get in the breather tube and the crud was sucked out both valve covers it probably worked. How efficently though is another story as the valves themselves are weighted for specific applications...
 

·
Registered
Joined
·
230 Posts
Discussion Starter · #5 ·
Thanks Dennis, that's what I needed to know. And I thought I was so smart.

So what your saying is that by having two PVCs I might have altered the air pressure enough that they both may or may not work correctly—like not being able to open up enough to truly evacuate the system? Do you know if there's a way to check that?
 

·
Premium Member
Joined
·
8,375 Posts
Ken,,,,, how do I say this politely? Hmmmm, OK, how about this:?
The guys are using the acronym PCV for Positive Crankcase Ventilation. You are using PVC for Polly Vinyl Chloride. Knowing this group of guys, I think they are hoping that you will GET IT without anyone have to mention your error. Plastic water pipe isn't good on these cars.
 

·
Registered
Joined
·
230 Posts
Discussion Starter · #7 ·
Can dislexia happen at 54, or would I have noticed it sooner?

Actually I AM talking about PCVs. Thanks for the polite correction.
 

·
Premium Member
Joined
·
7,728 Posts
Thanks Dennis, that's what I needed to know. And I thought I was so smart.

So what your saying is that by having two PVCs I might have altered the air pressure enough that they both may or may not work correctly—like not being able to open up enough to truly evacuate the system? Do you know if there's a way to check that?
The PCV system is designed as a continuous-flow system - it pulls in fresh air from the air cleaner through the passenger side valve cover, the air goes through the crankcase (picking up hot vapors), and exits through the (metered) PCV valve in the driver's side valve cover, through the hose, into the port in the carb base, and is drawn into the cylinders with the incoming charge. The elbow in the passenger side valve cover is the ONLY point where outside air can enter the crankcase.

If you have TWO PCV valves, one in each valve cover, teed together into one hose to the carb, vacuum is pulling at both PCV valves, but there's no place for fresh air to enter the crankcase, so no vapors are being extracted - all you're doing is pulling a constant vacuum on the crankcase, not ventilating it, since there is no airflow.

Take the second hose off and put it back the way it came from the factory so it'll work. :)
 

·
Registered
Joined
·
230 Posts
Discussion Starter · #12 ·
All you guys are really helpful in your offers of advice. Thanks. I've learned a lot reading your advice on this and reading the conversations on other threads/issues. I really appreciate it.

I am trying to get it back the way it was, hence my restoration of the original air cleaner. But the problem still remains finding the missing straight vent tube. If I had found it I wouldn't be in this situation.

I am going to have two PCV setups, I can swap out. One for my original air cleaner for shows, and one with the after-market open element set up for when I am just cruising around town—that is IF I ever get this thing finished.

Thanks again.
 

·
Registered
Joined
·
125 Posts
I was able to get the parts (used original straight tube and curved hose) for my '68 L30/M20 from Camaro Country (269) 781-2906, ask for Jerry. Hope this helps, RonM.
 

·
Registered
Joined
·
230 Posts
Discussion Starter · #16 ·
Thanks Ron, I'll try them again. I tried to get in contact with them for something else and never heard back.
 
1 - 16 of 16 Posts
Top