A Special Builder's Notes


The Special Builder's Breakfast Club

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05 April 2015

Passed Fit.

Having given myself the all-clear, The Ambassador's Daughter and I took off to Ufford in the Hillman for the first serious meet of the year. A damp start and a chilly Northerly did nothing to quell everyone's enthusiasm and there must have been a good 70 - 80 cars on the field by 2.00pm at the White Lion.

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To get a bit of a leg up on the way, I elected to do the first 10 or so miles on the A14 dual carriageway - just to blow out the cobwebs. That was fine but when we got onto the smaller roads the temperature under the bonnet rose pretty sharply (despite the electric fan) and the engine died at some traffic lights not far from our destination. I've got to get to the bottom of this. The Paxolin gasket alone hasn't worked so I'm going to add an aluminium heat shield and put a duct in the bonnet to wash cold air over the carb. I could also, by way of experiment, disconnect the air cleaner which makes a contribution to the heat in the carb body as it pulls in warm air from inside the engine compartment.

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There was an interesting Jupiter (one I'd seen at Silverstone a year ago) to have a look at and I learnt from its new owner that it was now only a few miles from Learned Counsel; no doubt we shall ask to visit and swap notes. The other thing I thought about whilst trying to fathom out the fading problem was that it might be too thin an oil in the SU dashpot. When the engine and carb get hot, the oil might thin still further and on depressing the throttle, the vacuum could get ahead of itself and the choke body might momentarily pull in too much air and not enough fuel (this wouldn't explain fading at the traffic lights but might make a contribution to a hesitant pick-up when the engine's hot). It's a possibility so I asked the question of Mr Wolseley and he recommended 20/50 to keep the mixture rich - modern fuels being part of the problem.

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I was still feeling a bit rubbish earlier in the week so to cheer myself up I perched the rear part of the body on the racing car - just for larks and to see how it was taking shape - and started to think out a frame arrangement for the shell to sit on. This threw up a couple of questions that I can put to Mr Riley next week. The first was, can I run an open propshaft on a torque tube gearbox (I can't think why I shouldn't) and secondly, is there any point in using the big and heavy pre-war rear axle if we're not going to be messing about with the gearing.

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That looks about right - a touch low at the moment but the new frame will take care of that.

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So whilst everyone was gorging themselves on chocolate, I got on with my painting. A whole day went past and before I knew it, it was time for supper. I'm a bit out of practice - it must be 2 years since I last picked up my brushes - so some of the draftsmanship wouldn't bear too close an examination at the moment but, I daresay that as things progress, it'll pass muster.

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next post Not Good.


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