Metallurgy

Hello Everyone,

There are several threads having reference to the cam chain issue in our V-12s.
Like everyone else I am afraid of the ramifications of a loose chain.

Recently Alistair showed no stretching of the chain he removed while he was into it's case. After all, the manual says to change it. He demonstrated there was no stretch in the chain at all.

I asked a Caterpillar field rep about chain stretch. His view was that the wear has to do with revolutions and not torque. So here is our situation: the manual was written 30+ years ago by a company in Europe where these cars could be run flat out all day. Perhaps the wear situation they expected was different from our use of these cars in the US. We may run them "On the New Jersey Turnpike in the wee wee hours..." but not for very long.

So here is my question: does anyone know the hardness of the chain and the material and hardness of the adjusting shoe?

In one thread the question came up about shoe wear and I suspect this is where the $1,200.00+ problem lies.

Greg

 

I've never heard of cam chain issue with any Ferrari engine. Don't they use a triplex chain?

Pete

 

We do not have chain stretch in in American V-8s either. But then the chains in them are not 4 or 5 feet long. So I suspect adjuster shoe wear as the problem in the Ferraris.
Greg

 

The 'Renold' chain is case hardened on the outside 10 000th inch to 700+ Vickers. The inside is around 450 Vickers. The pin ends are softened to around 450 to benefit rivveting. Just for info for those joining links the pins are 3.2mm diameter and need to be peined to 3.35mm. The pads are made out of I think hard rubber/uerethane maybe mine were showing signs of wear but not enough to warrant replacement.

As mentioned earlier there was no stretch in my chain and it would have lasted another 30 000 miles You can check your chain tension by the following: slacken off adjuster till you hear it rattle and then make up (not so keen on that) or take off the cam end cover on iether side between the two pullies (gears) the chain should deflect 1 mm with a force of 20kilos on it. so it should feel pretty tight pressing your thumb down on it. Too loose and the cam timming will suffer.

Check the wear on the tensioner pad by undoing it with the six nuts.
Other factors to be considered are the bearings on the driven shaft mine had excesive play and water/oil pump rebuilding bearings etc. In which case its engine out. In summary I suppose its a number of factors that need to be considered not just chain.
Regards
Alastair