Duplex timing chain and tensioner

[moggiegeek]

I'm building up a 1275, and just at stage of machining work.
I'm wondering specifically about whether it's advisable to fit timing chain tensioner to new Duplex Vernier timing chain set up.
The minor front plate is already being countersunk for screws at crankshaft aperture in front plate.
Using the Marina front plate as a template I've got the 16mm dia hole for the tensioner in the new plate but would you advise:
a) fitting it
b) if so, could I use a very lightly used one I have from a 1275

[philthehill]

The 'A' plus tensioner pad fitted to a duplex set up is the best way of keeping the chain tensioned on the slack side of the chain run.

I use the 'A' plus tensioner pad on my 1380cc full race motor and it is exceedingly good. See photo below.

timing chain tensioner.jpg (1.17 MiB) Viewed 1720 times

Providing the tensioner pad has not too much wear you can use the original Marina/Ital item but as they are so cheap it would be better to use a new thrust pad. Set the tensioner carrier so that the carrier securing bolt is about halfway to threequarters in the slot.

http://www.minispares.com/product/Class ... o%20search

If you are using the original Marina/Ital timing chain cover ensure that the circular baffle/shield surounding the breather/oil separator hole is removed otherwise the duplex will foul.

100_2212.JPG (1.86 MiB) Viewed 1719 times

Timing cover 2.JPG (1.6 MiB) Viewed 1719 times

When fitting the duplex set up you will also have to remove the timing sensor bracket and knock out the dimple.
Below is a timing cover with both the bracket and dimple removed.

100_2411.JPG (1.46 MiB) Viewed 1716 times

[moggiegeek]

Thanks Phil. As advised I've ground away the circular ring on the timing chain cover until it's level with the base of the ring but still a few thou proud of the actual cover. Is it necessary to remove all traces of the ring?
I'll get a new pad for the tensioner.

[philthehill]

Not absolutely essential to remove all traces of the ring but I removed it completely because it looks a better job.
All I did to remove it was grind away the spot welds and the ring can then be lifted away.
Make sure that any grind dust is removed from the oil separator as if it gets back into the oil it will cause damage. You can always remove the gauze in the oil separator housing, fully clean inside and then stuff one or more stainless steel pan scrub into it.

[moggiegeek]

Good idea re replacing the gauze.
Which dimple are you referring to? There is one on the cover periphery alongside the cover bolts. Is this the one?
Slowly getting to the reassembly stage now!

[philthehill]

The concave dimple in the cover is looking at my top photo - top left. The dimple is to accommodate the timing sensor. There is also a bracket on the outside of the cover (again remove) which holds the timing sensor. It has to be removed otherwise the timing chain will wear through it.

[moggiegeek]

Hi, realised my cover is a 1275 pre A+ though the engine does have the internal can followers.
So no dimple as in photo only one about 6mm diameter on periphery between bolt holes.
Removed old gauze and retaining paperclip type wire. Will refill vent top with stainless steel gauze so the oil mist can drop out of suspension.

[philthehill]

To be absolutely certain that we are singing from the same song sheet can you please post a photo of the timing cover you intend to use.
There are several types of pre 'A' Plus timing chain covers and I want to make sure that you are being given the correct advice.

Phil

[moggiegeek]

Currently can't compress photo images. However the dimple is clearly part of the strengthening pressings on the rim.
What other distinguishing features might be significant?

[philthehill]

The dimple is not there for strength but to accommodate the timing sensor. The dimple can be there because of the simplex but it cannot be there when the duplex is fitted.

The timing chain cover in the link below has the timing sensor holding bracket attached and dimple under it:-

https://www.ebay.co.uk/itm/CLASSIC-MINI ... SwtYtdNJa1

Does your timing chain cover have the timing sensor bracket attached?

[moggiegeek]

Thanks for photo, no it's very clear from eBay photo I don't have bracket or dimple.

[philthehill]

Going back to basics - Has the engine been up to now fitted with a simplex set up?

If that is the case you have timing chain Pt No: CAM4868 which does not have the timing sensor bracket or accommodating dimple.

Removing the oil baffle ring as you have already done is all that is required plus countersinking the two 1/4" UNF front engine plate bolts. Use counter sunk Allen headed screws and Loctite in place.

http://www.minispares.com/product/Class ... o%20search

General info:-
After market timing covers may have the dimple but not the timing sensor bracket - if it has a dimple it needs to be removed.

http://www.minispares.com/product/Class ... o%20search

[moggiegeek]

Yes that all adds up thank you.