Brian and others who replied re TR4A breather plug. This engine was
rebuilt by a professional British Engine shop in Eugene, OR. They soaked
the block to remove rust, therefore replaced all plugs, so I assume they
simply forgot to install the 4A plug or thought it was a 4 engine with a
breather tube. I installed all accessories and the engine in the car. At
initial start, I had a very hard time with the carbs due to a vacuum
leak in the breather system. I finally gave up and took the whole car
down to Eugene and had them set the carbs. He did redo my work on the
pancake breather. Now, I wonder if I install the plug as a TR4A engine
should have, if that will change anything in the current set up. Guess
I'll have to try one. Certainly don't want to have a breather tube on it
after all my effort to make this car correct. Comments?? Jerry
Brian Sanborn wrote:
>
> On Tue, 1 Jun 1999 22:14:46 -0700 (PDT) walker05@camosun.bc.ca wrote:
> >
> > On Tue, 1 Jun 1999, Jerry Oliver wrote:
> >
> > > Does anyone have an idea what effect not having the breather plug in the
> > > block on a closed system engine would have? I was under my car (66 TR4A
> >
> > Oil vapors escape and cause quite a large oil spot somewhere in your
> > engine bay.
> >
> > On my TR4, which has a TR4A engine and no PCV (just a stub sticking out of
> > the valve cover- I intend to do something about it someday...), there's a
> > football-sized "spot" on the underside of the bonnet. I notice no
> > problems with the engine. (However, I've never been priveledged enough to
> > witness what a TR engine is supposed to be like)
> >
> > If you have a hole in the side of your block and no draught tube, either
> > install a plug or a draught tube. The tube has a 'trap' in it to stop
> > anything nasty (water and brake fluid come to mind) from getting into your
> > engine. I vote for the plug, especially if you have a breather on the
> > valve cover.
> >
> >
>
> Malcolm,
>
> I usually agree with you... but not this time. I also have 66 TR4A engine
>in my 62 TR4. I was not happy with look or more importantly the terrible
>design and function of the PCV valve setup. It had bad variable air leaks
>which caused highly variable idle and mixture.
>
> I beleive that it important to do one thing or the other. If the hole is
>open you must have a valve cover that has the breathing oil filler cap and you
>must have the draught tube installed. The venturi shape and angle of the tube
> provides a pro-active air flow through the engine and negative pressure to
>clean out exhaust gases and what not.
>
> In the PCV setup the engine is sealed up tight and the blowby gases are
>sucked back into the intake stream and the PCV valve is supposed to maintain
>this negative pressure inside the engine.
>
> The negative pressure is important to the rear seal operation. Without the
>negative pressure provided by one setup or another.... the pressure pulses
>inside the engine will blow oil out past the rear seal which depends on air
>flow into the engine.
>
> I experienced this when I first bought my car. The PO had put a cork in the
>PCV hose to stop the air leak and had not changed the valve cover arrangement
>and the car pumped oil out of the rear seal. I removed the cork and the ALL
>oil leaks stopped but the engine was a very unstable at idle and setting the
>mixture was imposible.
>
> I have retro-ed my engine back to the full breather setup for both
>originality and the better engine behavior. The engine has a rock steady idle
>and better control and I can start tuning the mixture more precisely.
>
> I have an extra draught tube and early TR4 valve cover from a junk yard
>engine if it will help you or Jerry.
>
> Brian Sanborn
> 62 TR4 CT16260L - Groton, MA
> sanborn@net1plus.com
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