7 replies to this topic

[Trissy B]

Hi, i have a 1275 A+ metro engine with a duplex timing chain as pictured with tensioner (i assume this is all standard).

 

I'm about to go through a head rebuild and have decided to change the timing gear at the same time as its quite rattly. I've recently brought a Piper lightened vernier duplex setup to go on to allow me to get the timing bang on.

 

1. this doesn't have a tensioner included. Shall I keep the standard one in place anyway? or better still, get a new replacement. and

2. Everyone talks about countersinking the bolt under the duplex chain. Presumably this only applies to mini engines where duplex hasn't been fitted before and I can ignore this?

 

Many thanks,

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[Compdoc]

Yes. fit a new tensioner and your fixing bolts should already be countersunk into the front plate so will not touch the sprocket.

[Midas Mk1]

Swiftune instructions for their duplex state not to run a tensioner.. 

 

After searching on here I went with their advice. 

[cal844]

Duplex is a mod, but should just be like for like, no mods required

[Cooperman]

The tensioner is designed to run with a Simplex chain where the edges of the chain are in contact with the tensioner. With a Duplex the tensioner rests on the centre of the chain.

I have seen one tensioner pad broken due to this single centre line loading, but that was on a high revving engine. I have also seen one about to fail, but again on a high revving unit.

It's personal choice really. The original Mk.1 Cooper 'S' ran a Duplex chain and no tensioner and it worked fine. If not fitting a tensioner make sure you have a top quality chain.

[Spider]

I've built and have a number of engines that I've fitted Duplex Chains & Sprockets to and run with the late Simplex Tensioner. 99 times out of 100, even if the tensioner shows some wear, as long as the spring on the back of them has enough tension, I refit them.

 

I've found in the days before these tensioners were about that with the Duplex set up, they rarely get noisy but it does help hold the cam in better timing and you'll see this with the timing light, particularly at lower speeds.

[Trissy B]

brilliant cheers for the advice

[ACDodd]

What moke spider said!

Ac