Race Engine Forum UK

I've recently started my rebuilt engine. I notice after perhaps 1/2" hr of running at 1500-2000rpm the timing belt has walked towards the engine such that about 2mm is no loger running on the exhaust camwheel or the tensioner. The belt is running just off the inlet pulley flange, there's no damage evident to the belt.

Some wear was evident on the crank pulley during the rebuild but nothing drastic.

The pulleys are flanged as follows:

Aux - Front
Inlet - Rear
Exh - Front
It's a standard 3/4" wide belt

A: Should I worry about it
B: If yes to above what can I do about it.

Thanks,
Stuart

Stuart, hi

that's not good. Someone rang me lately with that problem and it happened because the worn tensioner pulley had developed a taper on its diameter. Check yours.

I don't know any other possible cause other than if the head is not machined true it can sit slightly 'tilted' on the block causing that effect. That I have seen.

GC

Hello Stuart:
In my Beta I had the same problem.
I saw that when the tension is too big,the cam belt goes to the motor,and when the cam belt tension is too low,it goes outside to the right side of the car.
I don‚´t know if it helps, but if you can set the tension at the correct point it should be good for this purpose.
Best Regards,
Siro,

On a rebuilt engine, I would definitely be fitting all new pulleys and tensioner. Seen this happen on many Twin cams over the years due to tapered pulleys or tensioner. it can even happen if the wrong cam pulleys are fitted.
A loose cam belt can also move around.

Andy.