triumphs
[Top] [All Lists]

Re: Repost: TR-4A - missing PCV valve spring

To: John Cowan <jfcowan@earthlink.net>
Subject: Re: Repost: TR-4A - missing PCV valve spring
From: "Chris Lillja" <Chris_Lillja@pupress.princeton.edu>
Date: Wed, 22 Oct 1997 15:39:11 EST
Cc: triumphs@Autox.Team.Net
Organization: Princeton University Press
> Questions:
> 
> 1. What is the function of the spring, disk and post?

... as I understand it -- the "Smith's Anti Pollution Valve" is a 
vacuum regulator, not just a check valve. The idea is to keep a slight 
vacuum in the crank case at all times. This helps keep oil on the 
inside of the engine. This is a good thing. The gases in the 
crankcase are mostly blow-by fuel/air from the rings. Burning this is 
a good thing.

> 2. What is the effect of the spring being missing?  Dangerous to the engine?

I guess it means that the regulator is stuck in the "closed" position 
-- I don't think it would hurt anything --- except it might not be 
scavenging the crankcase effectively at speed.

> 3. If it were, could I just disconnect the PCV valve from the system and
> plug the hole in the intake manifold for the time being?

--NO! Unless you want oil on the OUTSIDE of the engine where it does 
precious little good.... Even just venting it doesn't work as well.... 
the engine blocks are different -- the earlier blocks are 
vented down near the sump!

> 4.  It seems like at tune up time, one is always trying to eliminate leaks
> in the intake manifold. Doesn't the PCV valve act like a leak in the intake
> manifold, with similar bad consequences?

No -- it's referred to as a "closed system" and, it still should 
be, unless something is wrong....take the oil cap off while its 
idling -- it will (should) stumble if not stall....

> 
>    The missing spring not available from any of the usual suppliers.  I may
> have located a source for a suitable replacement.  If so, it would be good
> if the suppliers picked up on it. Anyone have experience working with the
> suppliers to develop replacement parts sources?

Please let me know about your source. I'd just get a used one if I 
couldn't find new....

Anyone, please feel free to correct me if I'm wrong on any of the 
above points. 

In general I feel that this system is much maligned as a dreaded 
power robbing "smog device"....All it's doing is recirculating 
fuel/air charge which should have been burned in the first place and 
got by the rings! These things appeared before any pollution controls 
became mandatory (I think, after all I was only one or two at the 
time). Like the rest of our TR's -- it's simple and very effective!

Hope this helps!

"Still ride in triumph over all mischance..." - Shakespeare

Chris Lillja
TR4A
Norton Commando
Spit MKIV

<Prev in Thread] Current Thread [Next in Thread>