Friday, 14 November 2014

A moment's pause.......

Well, time sure does fly.

I woke this morning to rain hammering down on the roof and the slightly more reassuring sound of our wind turbine moaning away as it tops up the batteries with lots of nice free amps.

A rainy day off then........

What to do?

I know! I'll open the long-closed door to the room where I blog. . . . .

Do you remember that rather clever advert for lager? The one where someone working in a large office building hears an old-style phone ringing in an unoccupied room? They open the door to find themselves in The Carlsberg Complaints Department, clean, tidy, decked out with state of the art technology c.1937.....and eerily deserted....... And of course, the phone call is a wrong number........

Well, coming back to the blog has been a bit like that.

Except for the fact that it's covered in dust, and behind the door was a pile of leaves and something unspeakable which was probably brought in by Thomas or China, our on-board felines.........

It's taken a good hour or two to clean up........

Anyway, what's been occurin' down in Groovetown?


I've had a few polite requests for some updates on the Alvis restoration, so, David Attrill, Kath on nb Herbie, and Dad,...... I'll start there.

(Whether this develops into a more general update very much depends on the weather. If it stops raining, I'll have to get to Tesco for some groceries, the Tip to do the re-cycling and possibly Emmaus for a bit of a mooch.......)

Anyway, the Alvis......

Progress has not been as rapid as I had hoped. In fact it has slowed to an almost glacial pace.

Progress has, however, been made.

The cylinder head has been rebuilt. (I very nearly blogged about this at the time, which was in June, under the title 'Getting My Head Tested'...... but the moment passed.....)

First, I took the head from the spare engine to The Test House, where £50 bought a crack test.

This involved a couple of very helpful chaps running an absolutely huge magnet over it.

It looked just like the sort of thing that Wile E. Coyote would have used in his attempts to nobble The Road Runner - all it was missing was the 'Acme Magnets' stamp.....

My head was then tested for straightness (Lord alone knows, a warped head you do NOT want.....), and a written report was submitted, declaring it straight, not cracked, and fit for purpose.

Which will, no doubt, come as quite a surprise to some of you.........

I then lapped the valves in by hand.
Actually the o/e head, this gives an idea of the coke and crud that first had to be removed from the spare one, below.......

 to get it looking like this.......

Valve-lapping in progress.......

This took bleedin' ages, and gave me some nasty flashbacks to the 10 thou. hone of the cylinder block.

(That was the sort of job where at some point you begin to wonder whether you have, in fact, just been involved in a gas explosion and are, for your sins, destined to continue it for all eternity....).

Number 3 cylinder exhaust valve is normally problematic on four cylinder engines as it is often furthest from any coolant. It's therefore most likely to be burnt, pitted or generally knackered.

No. 3 exhaust on the Alvis engine was no exception. The valve and seat were both quite badly pitted.

 You can see the pitting on the valve port face here, at about twelve o'clock...... it looks better than it was:

I spent at least a couple of days hand lapping the valve and seat with a mixture of coarse and fine grinding paste. (It felt like a lot longer.....)

This left the valve slightly 'pocketed', which means it's sitting too far down in the seat.

This can cause problems as it affects the smooth flow of exhaust gas: exhaust gases swirling over and around the overly-high lip of the valve seat result in the engine being down on power. It could also cause No.3 cylinder to coke-up with carbon deposits very quickly.

I swerved deftly around this problem by borrowing a valve seat re-facing tool from my chum Roger.

 A very few twists of the tool removed the unwanted lip and got rid of the remaining pitting in the valve seat.

This left me wondering why I'd spent so long sodding about with grinding paste when I should have just 'Asked Roger'.......

Anyway, here it is, looking very nice.

 Unwanted raised lip and remaining deep pitting removed......

I then hand-lapped in a good valve from the spare head.

(As I've got the original engine's head, the head off the spare engine, and another spare head to choose from, I was going to blog about this under the title "Three Heads are Better Than One"......

It was a toss-up between that and "Lapping It Up".

In the end I did neither, so consider carefully that from which you were spared, and go your way giving thanks.....)

I then broke out the valve spring compresser and fitted the valves, springs and collets into the sparkling clean, de-coked, de-rusted, de-silted and freshly painted head.

Eagle eyed Alvis TA14 enthusiasts who have blundered into this nonsense by means of Google (or by a simple innocent mistake....) will notice that the third valve assembly from the left is assembled incorrectly: I got the outer of the two springs per valve the wrong way up.......

Fortunately, Roger spotted the error of my ways when I took the head over to his house so we could blast it clean of any last tiny crumbs of grot with his compressed air line.

So I took it home, dismantled it yet again, and reassembled it correctly......

In doing so, though, I followed Roger's advice and departed from  the factory's original plan by leaving out the inner of the two springs per valve altogether.

Roger runs his gorgeous Speed 25 on single springs with no problems, and suggested I do the same.

The rationale is this: The double valve spring set-up can cause problems with the valve seats as the valve smacks shut with such force that it can speed up valve seat recession. I shall run the car with the single spring set-up. If any compression problems develop, I'll let you know.......

Around this time (August), I decided to de-rust and paint the exhaust manifold.

 Showing lots of rust.........

Some time later, after a lengthy interlude involving angle grinders, PPE, and 30 grit abrasives....

And after three or four cans of Hycote VHT matt black aerosol paint.....
(The 'hot-spot' plate  is clearly seen here, centre.)

To do this, I first had to remove the inlet manifold, which led to an interesting discovery.

The cast iron exhaust manifold has a shoe or plate cast into it on which the alloy inlet manifold sits. (See above picture of the newly painted manifold)

There is a hole machined into the inlet manifold where it sits on this plate, viz:

The idea was that the heat from the exhaust would pre-heat the fuel/air mixture from the carburettor and aid combustion.

(In the immediate post-war period, when the only fuel available was 'pool' petrol, a very low octane brew, this was probably a good idea.

Today, the stuff they call petrol is a very different thing indeed. It burns much hotter, and has no tetra-ethyl lead in it.

(As an aside, while causing no end of problems for the environment, leaded petrol did stop pre-ignition or 'pinking', helped to prevent valve seat recession by providing an upper cylinder lubricant, and generally 'improved' the performance of the fuel........ while causing brain damage, foetal abnormalities and all sorts of other ghastliness.

It may also be worth noting that the person responsible for putting lead in petrol also came up with the wizard wheeze of using chloroflourocarbons in refrigerating equipment, which promptly buggered the ozone layer.

Nice one, geezer....... ).

Anyway, if the inlet/exhaust manifold was left as original, I foresaw real problems with fuel vapourisation.

(This is caused by excess heat vapourising the fuel before it can be combusted in the cylinders. Have you seen a classic car at the side of the road, bonnet up, on a hot day? Odds are three to one favourite that fuel vapourisation is to blame.)

I took the problem to Roger, who agreed that the current set-up was bound to give just this sort of trouble.

After a meditative ale or two and much scribbling on beer mats and backs of envelopes (the once de riguer 'back of a fag packet' has fallen hopelessly out of fashion.....), we decided we needed a couple of spacers to go between the inlet manifold and cylinder head.

The idea was to raise the inlet manifold away from the hot-spot on the exhaust sufficiently for us to make and fit a nice thin 1.8-2mm alloy plate to cover the hole in the inlet.

After a swift sift through his stock of 8mm alloy plate to find a piece suitable for purpose, Roger and I spent a goodly few hours machining these spacers up.

We used an old inlet manifold gasket as a template. I have to say it worked really well and looks very nice. There is also now a gap of a few millimetres between the hot spot and the plate on the inlet manifold. This will hopefully further reduce the heat being absorbed and thereby also help to prevent the fuel from vapourising.

Sadly, I was too busy helping with the fettling to do any photography.


Anyway, the proof of the pudding, etc etc, so Alvis Afficianados, watch this space.

It'll be interesting to see if it works...........

Having done all that, I completely dismantled the rocker shaft that came with the head from the spare engine.

Lots of notes and photos were taken so it all went back exactly as it should after a painstaking clean of every tiny component.

I then had a hard, critical stare at the state of the pads of the rocker arms.

They were too heavily worn for re-use.

 More pitted than a South Yorkshire hillside, pre-Thatcher........

What to do?

Before spending the equivalent of the GDP of Peru on a new set of rockers from Alvis marque specialist Red Triangle, I decided to investigate the ones on the totally crocked original engine.


 Almost as new, with minimal wear!

Result indeed!!

As the rest of the original engine was so far gone it was all beyond economical repair, clearly some kind soul has, in the not too distant past, renewed them.

(They are at the top of the engine, so it's a fairly easy job which would have transformed a very clattery old nail of an engine into the smooth but very smokey unit that came with the car. It was probably done to disguise how bad the engine really was, but I still find myself saying "Well done them!" :-)

Anyway, I whipped the good rocker shaft off the shagged-out engine, repeated the slow, painstaking strip, clean and rebuild process and placed it atop the reconditioned head.

 I was going to blog about this under the title ' He's Off His Rocker', but once again, the moment passed me by.

Be thankful.

There was then a bit of an Alvis hiatus while I got distracted by life and jobs until a couple of weeks ago when I finally got around to dropping the reassembled head onto the block.

I have yet to tighten it down: there are no torque settings for the TA14. The book gives you the order to tighten the bolts up in, but you have to do it by feel........

I've borrowed a specially adapted spanner form Roger to do this (You can't get a socket or ordinary spanner on the nuts which hold down the rocker gear.....).

I really should get on with it.



The rain's stopped.......

But I've spent so long blogging that it's now dark.......

Foiled again!


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