The very last A series small bore blocks, on the last minis imported into Canada, had single row timing chains and tensioners. The transmissions also had features that A+ transmissions. I have often thought these would be a better basis for a hot small bore engine, and considering Alex's recent thoughts on the quality of cast iron between the two, I hope one day to build one.

There is also a dimple in the timing cover that needs pounding flat and the breather shield in the cover needs cutting out. I'm changing early pre A+ engines over to later front plate and timing cover to take advantage of tensioner. Due to the shape of the block I cut half the head off a 5/16 bolt to secure the timing cover. While I have done duplex with tensioner, for a street car with std or near std cam, springs and rpm expectations I'm not sure it is required. Steve (CTR)

I changed mine over to the duplex. Kit came with the tensioner. Obviously much easier to do with the engine out of the car.
I also ordered the same for a friend. There are two screws to counter sink for the dual conversion.

I have IWIS duplex chain & tensioner in the 1293cc build for the Woody.  No apologies. 

Yours will look like Richards set up (previous post) when you get it apart. Don't forget to change the radiator hoses and water pump while you have it apart.
Look on You tube there should be a video on there of this job.
Have you got a Haynes manual ? If not get one for $35 or so they are a must for a newbie.

So, as it turns out, I have an A+ motor according to the serial. Don't  judge, I'm new to this.

I ordered the upgraded single chain, tensioner, seal, gasket, pin, tensioner bracket. 

Anyone have a video or step by step they can recommend to get this done? Going to try next weekend. 

I agree replace with IWIS single chain and tensioner and never look back. I have quit messing with duplex. How many can honestly say they have put 100,000 miles on a mini or combination of minis. The hot offering in race timing from Swiftune is IWIS  single chain with alloy cam gear, use for season throw away. Engine builders time street cams a little early looking for 1.5 degree of stretch early on. Steve (CTR) 

It is not difficult, although is easier out of the car. I converted mine to dual. You need to be careful to line them up properly.

Small bore A+ units have the tensioner, and you can fit one with a duplex kit.

It's well worth upgrading the chain to an IWIS one, as the normal ones sold these days strtch like never before.

A single row IWIS chain negates the need for a duplex chain, and has less drag so makes you go faster !

The mechanic said that he thought replacing to a duplex meant there was then no tensioner...is that true?

Also, if the chain looks good, is it stupid to just replace the tensioner alone?

I replaced the single gear/chain set on the 998 when the MG Metro cam went in years ago for reliability and have used duplex gears/chains since...with the tensioner.  Even with good chains the tensioner wears, right in the middle of the pad.

I will continue to use a tensioner with duplex setups.

Easy enough with the engine off the radiator side mount and the radiator removed. If you have a single chain convert it to the double one replacing the gears as well, it involves minor drilling to install countersunk screws and will last a whole lot longer if you buy a quality kit. When re installing the timing chain cover (with a new seal and gasket) before you tighten up all the cover bolts install the crank pulley so it is all centered (no need for the bolt) then tighten as many bolts as you can get to with the pulley in place, remove it and tighten the rest then re install the pulley. You might as well replace all the radiator hoses while you have it apart.
Later Mini's had a tensioner i was told early a series small bores never got them, if you have a kidney shaped cover with a small bulge it will have the tensioner.
Parts needed, timing cover seal and gasket, timing chain and gears kit.

Changing the tensioner and crankshaft oil seal pulley is relatively easy - I did an in depth how-to for Mini Mag a few years ago, that I know has helped a few do the job.

Changing the timing chain *ought* to be fairly easy once you can get at it, but I'm not sure i'd want to do it with the engine still in the car.

Hi folks,  86' Mini - 998

Just got off the phone with my mechanic. Great guy. Determined the noise I posted about earlier to be slack in the timing chain. Tensioner issue.

I know others have chased this problem so heres a few questions:

1) Do you replace the chain at the same time as the tensioner? Is it a "while you're in there" item?
2) What parts do I need? I've seen "seal kits" etc.
3) Is this something I can tackle? I'm pretty handy and have done all the work on my own, thus far.

Thoughts?