engine rebuild,any tips?

[Rob]

my 2000 has deeloped a big end knock at 3000rpm. obiously new bearings et are in order, but where and what to use? and how much to grind? any tips?

[leesellars]

Get it done professionaly done you will have piece of mind.

Lee

[Mike Stevens]

These engines are remarkably easy to work on - albeit a bit heavy! Over the years I have rebuild quite a few without any major issues. Yet.

Firstly you have to strip the engine. The state of the shells, and their size, will tell you a lot. If the crank journals are marked you may need a regrind, but since that is not particularly expensive it might be worth having done anyway and then replace the bearings with the correct size to suit. If the crank has already had one or more regrinds this makes it a bit more difficult as you don't want to go too far. Hence the size of the existing shells is useful information.

Feel the lip at the top of the bores. Again, the size of the pistons will give more information. If marked 'F' or 'G' (I think!) then these are original sizes. Any over bore sizes will be shown on the pistons. A small ridge at the top of the bore can be left with new rings fitted (with a special 'ridge-dodger' top ring). A ridge that's too big will require a rebore and new pistons. Another way to measure bore wear is to put a ring at the bottom of the bore and measure the ring gap. Then repeat just below the top ridge. Divide each reading by 3 and the difference in the readings is roughly the difference in the bore diameter between worn and unworn parts of the bore. This is therefore the wear. Of course, if you have access to an internal micrometer, you can measure it absolutely!

Apart from that, obviously new gaskets and seals are required, but this simple approach should easily give you an engine that will be good for another 50k miles + with fairly minimal outlay. And you've done it yourself!

Cheers,
Mike.

[JimB]

Excellent advice Mike - you've pretty much convinced me to give it a go when the time comes

I'm a novice but am mechanically minded, although it's the little tips and tricks I'm lacking, e.g. spotting faults or damage specific to components (to ensure the right new parts are sourced) and how to ensure things are lubricated properly on reassembly (to avid wrecking on first start-up).

Wasn't there a recent magazine article on rebuilding a Triumph six pot?

[2SwissTriumphs]

Wasn't there a recent magazine article on rebuilding a Triumph six pot?

Yes indeed - Practical Classics May 2013 issue. Plenty of pictures and information, with it and a workshop manual you should have no trouble.

Regards,
Martin.

[Clifford Pope]

One weakness in the engines is the design of the end-thrust bearings, which are too insubstantial for the power of the clutch. Excess wear of the bearing block or crankshaft is a major problem if it has occured. Or so I think I have read.

[Mike Stevens]

There is a good fix for the thrusts issue. I have a TR6 engine where the thrusts had dropped into the sump. My local engineering company faced off the damaged part of the crank and made up some solid (phosphor-bronze I think) semicircular bits which were screwed (and peened) onto the main bearing cap and its upper part. The front thrust stays as original and can be use to set the end float.

Of course, this is not really an issue with an auto!

It was good to talk to you on Friday Jim. I'm sure you won't need to do any work on your engine soon, but apart from being heavy, they are an easy engine to work on.

Cheers,
Mike.

[Charles H]

I had an auto box 'eaten' by the end of the torque convertor due to excessive end float!

[Mike Stevens]

I had an auto box 'eaten' by the end of the torque convertor due to excessive end float!

That's interesting Charles. My statement about not being an issue with autos was based on the fact that with no clutch pressure there should be no extra wear on the front thrust washer, (I may have said rear yesterday!). Obviously there is some other mechanism going on there!

Cheers,
Mike.