A Special Builder's Notes


The Special Builder's Breakfast Club

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01 November 2020

Fun And Games.

After I'd placed the order, I noticed the small print announcing that the 38tpi tap and die wouldn't be arriving until mid-November. I ran the tappet thread in and out of the valve stem with a bit of cutting oil and, over time, got the thread cleaned up to an acceptable standard.

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I had in the end to put the head back together in two stages. The first was to compress the springs and make sure that the slots in the valve stems engaged with the tabs in the locking washer underneath the tappet.

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This is essential as it allows the tappet clearance to be adjusted without the valve turning. Running the tappets right down on their threads, I was then able to remove the compression plate spacer (which you can't see) put the machined block on top of the plate (which spreads the load evenly across each set of four valves) and compress the assembly enough to get the camshaft bearings through the casting and over the top of the tappets.

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Some gentle persuasion with a knockmeter was employed at this stage. The valves should be adjusted to .015" hot so I've set them at .016" for luck.

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I collected the block from the engine boys - the bores have been machined to +.020". I noticed that there's quite a lot of corrosion on the mating surface which should be attended to. A couple of thou off the top should do the trick and although I now have a mill, I'm going to resist attempting the job myself.

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A call came through from Counsel and The Great Collector. They'd discovered that the A7 Military Tourer's nose cone had somehow been broken and as they wasn't familiar with the engine, could I come by and help? By the time I got there, the radiator was removed and the fan pulley had come off leaving its centre firmly attached to the camshaft. The pulleys are very fragile and over time, weld themselves to the taper.

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With the dynamo and its housing removed (a game in itself) the engine mounting bolts were undone, the engine jacked up an inch and the cone slipped off. The engine has to be lifted because the cone's bottom bolt is trapped by the road spring. Leon was able to supply a replacement pulley, so I popped over to their workshop just in time to hear the Coventry Climax start up with its new hairy cam. There'd been some snags in fitting the cam which Awkward and Leon eventually traced to a cam bearing holding open a valve because with the re-profiled lobes, the material removed was just enough for a journal to interfere with a tappet as the lobes and journals don't sit absolutely centrally in the cam carrier.

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The clutch drive cable on my mower broke and replacements are unavailable. The whole mower had to come apart (including using a cutting disc) to get at it. I don't think the manufacturer expected anyone to try and repair it, but that's half the fun.

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