Hi Ian its that "white rust" pockmarking the metal.
Really bad on the bit right in your face, the back panel.
I tried a wire brush and it just looked worse, made the pocks stand out.
I'll hammertone it a "zinc" shade and fill the pocks a bit!

Fred.

That's obviously how they got hold of that aluminium, not aircraft grade! Impurities in the melt.

Here is part 1 of a series showing all the moves I make in getting this set going again.
PDF sent to Brad.
In this part I put a few hours into the strip down , clean up and making individual parts workable.
The chassis has parts bolted back on and there is lots of work still to go.
I'll follow up with more parts as I get to them!

Fred.

Restoring a 1947 KL Astor Mickey, Part 1

Document uploaded to Post 18.

Hi Fred.

Looks great!

Like the same vintage HMV mantle, the negative feedback serves a worthwhile role in this set.

1. It is modified to boost the bass response to greatly improve the sound from the small speaker, especially at low volumes.
2. It greatly reduces the minimum volume talk-through that you normally get with a reflex design.

You might be able to simulate a tap with two resistors in series, in parallel with the pot.

Fred: reckon you should change the thread title to say resurrection.

Ian that makes sense.
I have not tried a reflex circuit before so can have a play with the feedback and see what it does.
Typical me, just forge ahead with out thinking.
Can do the resistor tap easily.
Fred.

Yeah Fred, the added complexity needed to get reflexing to work properly was the reason AWA developed the high gain 6BV7 - which made a much simpler radio. But the reflex models still outperformed a conventional design using the 6BV7. You can imagine, showroom floor, turn up the volume, "Wow, this radio is powerful!" Even if the highest 50% of the volume control is unusable, too loud and distorted!

The extra audio gain allowed designers to throw some away to improve the "tone" with negative feedback. No chance of that with just the 6BV7.

I think Langford-Smith at AWA invented the reflex circuit. It was first used in the Empire State models and was claimed, with some justification, to achieve "the performance of a full size 6 valve receiver using only 5 valves". Unusually for a mantle radio it has an RF stage.

After WWII there was one hell of a lot of recycling & repurposing. The Astor JJ chassis is also Aluminium.

The "Grey Fergy" of which I have one of, and has had a recent birthday after blowing the head gasket is a classic example of what went on.

The sump, engine front cover, the heat shield, thermostat housing, PTO shaft cover, Dash, and pushrod tubes are all aluminium as are bits of the starter & Generator. The paint was also bought as a job as surplus from the Royal Navy.

More interesting is they used an Aluminium plug in the cylinder head, probably to ensure it got eaten rather than the block & I have seen some shockers in recent times for scale in the heads & block (mine was not one of them). Why they don't use corrosion inhibitor in them beggars belief?

Two other interesting surprises are the gearbox which seems to be "Duralium" an alloy the Germans invented for Airships. I discovered why the hydraulic pump was so light when it had to be removed: Yep! Aluminium Alloy, apparently ex Lancaster Bomber.

Check the tuning gang, If the chassis has the oxide pitting, if the gang has Aluminium vanes, it may have done similar: And it often does.

The transformer lamination steel was a "Silicon Steel" which the Americans came up with. It was also coated to reduce "eddy currents" I believe?

I am surprised that aluminium pushrods would survive. Their life in any engine isn't an easy one. Are they thicker than a typical steel one?

Marc, using alloy or iron seemed to be a designers choice of material at least in motor cars.
I think back 80 years or so to the British designers Morris and Austin.

Having owned 1930's cars of both makes and size, a Morris Minor and an Austin 7 one could see the philosophies.
The Morris (a 1929 OHC) was solid iron, engine gearbox and diff.
The Austin (a 30's Baby SV) was alloy ditto ditto ditto.
Morris went for brute mass to get strength, Austin went for clever dimension of alloy to get both strength and light weight.
Thus in broad terms you had a Morris that weighed a ton, and an Austin that weighed half a ton!

The Austin had a much better fuel consumption, that vehicles are only now approaching again.
Mind you travelling in a baby Austin was like driving a pram with about the same speed and brake capability!
Would not quite meet todays standards!

Now I drive a Morris Major that has an iron engine (Morris) and an alloy gearbox (Austin).
BMC simply had to use the more complex Austin box in the Major, they simply did not have a cost effective box that could handle the torque of the Morris engine. The early Majors used the Alloy "Minor" diff but the engine would simply jack the crownwheel out of the housing and put a 1/2 twist on the axles. In the end they used an iron housing with a billet steel crown wheel carrier and quill splines on High tensile shafts just to get any decent mileage from the diffs, but that is another story......................
Fred.

Push rod tubes are similar too but shorter than the boxer engine in a Cessna. These are external and fitted like a boiler tube. The pushrod itself is a rod inside it.

One of the issues with the axles as well was that the case hardening went too deep and that made them brittle and assisted them in snapping with a high torque. The Zephyr & Anglia of similar era were a classic example of how not to design a gearbox and a large number of Ford gearboxes of that era left a lot to be desired /of pieces.

The inappropriate use of circlips and not using the traditional GM slop fit was one issue. The oil would get between the cup & sliding shaft & could not get out as the tolerance was too tight. That would then apply massive pressure along the shaft & it would normally destroy the cluster gear. The box in mine is number four.

Even that is an Iron engine "Corrosion inhibitor" is beneficial. For Fergy mandatory for the Iron on Aluminium battery & electrolytic corrosion, Zephyr just for rust (no Aluminium). There were no blocked ports or calcification in the Fergy's head after 34 years since last overhaul.

Marc

Ah, yes Brad, not the pushrods, just the tubes they go through that are pressed into the head.

I got an instant mental image of how long an aluminium pushrod might last! 10, maybe 20 revolutions of the engine?

With the right alloy, the reduced weight would be beneficial. But this is moot.

Ahhhh, fair enough. I was thinking about the same thing and wanted to know the secret, if any. What made me more perplexed was thinking back to the days when I 'upgraded' a Torana I owned - part of the job was fitting a Yella Terra head to the engine. It has two valve springs on each rocker arm, rather than the usual one. The pushrods I used with it (separate purchase) were about 2mm thicker than the standard Holden ones, but yes, all steel.

That's what you have not got to worry about on a "sleeve valve engine" No valve bounce.

Japanese did not like the aircraft with them, by the time they heard it, it was normally all too late.