[Healeys] 100 Engine Timing Chain Tensioner

[Mr. Bill]

We all have our own experiences and this is the first time mine have 
ever disagreed with the very knowledgeable John Harper's advice.  I 
would not use the tensioner ring on the cam sprocket.

The original owner of Red Car rebuilt the engine at 42,000 miles.  I 
purchased it in 1978 with 58,000 on the clock.  Although I am not 
positive, but having known him, I'm sure he would have replaced the 
tensioner and not used a lesser quality part.  Shortly after I acquired 
the car, the tensioner crystallized and shattered.  It immediately 
clogged the oil filter, dumped hard, BB sized pellets through the relief 
valve and distributed them throughout the engine.  I realize much of my 
problem was caused by the oil pump inlet screen hanging half off but I 
have seen that in several Healeys.)  Fortunately I was just glancing at 
the safety gauge, noticed the oil pressure needle was pegged and 
switched off.  I did not have any damage although it was a terrible mess 
to clean up, pulling every cover off the engine in situ.  (In 
retrospect, I should have pulled the engine.)  I also found the "BB's" 
in the oil filters during the next few oil changes. 
 
I've put another 40,000 hard but not racing miles on it and have not had 
any problems nor heard any rattling from the chain.  Also IMHO pushing 
the chain up toward the smaller, pointed ends of the teeth would not be 
a good thing.  I welcome any opposing opinions.

Bill Barnett
'53BN1M


John Harper wrote:
> Marv
>
> In order to keep the chain from rattling then the tensioned ring 
> should be fitted. However there is a downside. Very old or poor 
> quality rubber versions have been known to break up and get into the 
> sump. Here there has been occurrences of these bits of rotting rubber 
> getting into the engine oilways, blocking them leading to bearing 
> failure.
>
> I personally do fit these rings but I would advise trying to get them 
> from a good supplier. I am lucky because I have a few original BMC 
> parts still available. The other thing is to carefully check the gauze 
> on the pump inlet filter box to make sure that there are no non 
> standard holes or any other general damage.
>
> Regards
>> When I tore my engine down, it did not have the "Rubber Band" chain
>> tensioner installed. I'm building it back up now and would like the 
>> group
>> wisdom on the need for the tensioner. The cam sprocket I'm using is 
>> groove
>> for the tensioner so I could use one. I ask because I am really lazy and
>> it's going to be a real pita to install. I know some replacement 
>> sprockets
>> are not grooved so at least some engines are built without them.
>> Marv J