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More on my Edwardian Alldays & Onions
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jojo
Mud Obsessed


Joined: 11 Aug 2007
Odometer: 5250




PostPosted: Wed Sep 13, 2017 9:41 am    Post subject: Reply with quote

Thanks for the update. It is good to know that the car is now running nicely after all the work you have put in.

J
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RichardD
Marshall


Joined: 13 Mar 2003
Odometer: 22847
Location: State of Confusion



PostPosted: Wed Sep 13, 2017 9:44 am    Post subject: Reply with quote

Veteran car engines are about a simple as an engine can get. 4 stroke (Otto cycle) engines often with no oil, water or even fuel pumps, incredibly simple carbs with little external adjustment. So when they don't work properly it can be a real head scratcher!

Mine was rebuilt about 2 or 3 years ago with new piston rings, new cam followers and rebuilt and reprofiled cam and after much ******* around was making decent compression without any gas leaks mostly thanks to Hylomar. 55psi is low even for a veteran car (170+ is normal for modern cars) but Alldays were not known for speed or power but for reliability and once I'd got it tuned in properly which is along a drawn out process involving drilling out and resoldering the jets until it drives nicely, it was indeed very reliable.

Low compression means easy starting on the handle and slow but steady progress, easy hot starting but it was only getting around 14mpg on a good day and often as low as 10mpg and top speed of 30mph only be being thrashed.

So, there we were in Fife on day 2 of the VCC Scottish Main event at the end of September 2016 and it was a chilly start to the day compared to the day before. We started the car and set off for Kellie Castle as promptly as possible so we could arrive without holding everyone else up too much being one of the slowest cars on the Rally. As we drove off, Jacquie (my partner) remarked on how the car seemed to have a little more pep than normal and, as I was explaining that cold air being denser gives you a different enough fuel:air mixture to be noticeable sometimes, something went TING! in my head and I was suddenly very keen to get to our morning tea stop to test out a theory.

When I bought the car it has been in South Africa and had been fitted with an air filter which it would not have had (and didn't need)



I removed the air filter assembly and set it up as per the original drawings



The reason for this odd set up was carb icing, a very familiar problem for Zook owners with SU conversions. The carb sits at the bottom of the engine and as inlet manifold is so tall, the atomised fuel would condense out against the walls of the manifold and fall back down ruining the smooth running and starting. PHYSICS ALERT: Boyles Law or the Combined Gas Law says that the pressure of a given mass of an ideal gas is inversely proportional to its volume at a constant temperature. OR ... as fuel/air mixtures get pulled up the manifold it accelerates reducing the pressure, increasing the volume so the temperature drops causing the fuel to condense out. The solution is to heat the mixture, in modern cars by heating the manifold and in ancient cars by heating the air before it get to the carb. Once the engine is good and hot, and it gets very hot, you don't need so much heating so there is, I thought, a bypass pipe fitted for introducing cooler air - for hot Countries.

The normal route for the air intake is through the black square tube attached to the exhaust manifold from the back of the engine then down through the brass pipe with holes in it which slides around an inner pipe similarly drilled



Bearing in mind that the carb is a later aftermarket Zenith from around 1918 with a choke (that I don't use) the situation was a bit confused.

Anyway, back to Kellie Castle and morning tea. We sat and warmed up whilst I pondered the engine and then out into warm sunshine and to open the bonnet which always attracts attention. I set everything up and swung the lever and started the car. a minute or 2 for warming and I reached in and moved the brass tube round to open all the holes up. The engine note dropped, and tickover smoothed and it revved just a bit more ... solidly.

Off we went back on the route to lunch and the car ran like it had been fitted with a bigger engine, happily cruising up hills at 30mph, and accelerating. We went from slowest to one of the quickest with fuel consumption going from ~14mpg to ~22mpg.

It seems that this is the choke and I'd been driving with it closed for years!

Next problem is with cooling the engine now it can operate at full power - the 105 year old radiator cannae cope!

__________________________________
Poking the Grim Reaper with a stick then running away. The devil made me do it but God said it was okay with him.
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Nightbar
Difflock Royalty


Joined: 30 Sep 2003
Odometer: 20578
Location: In a state of anticipation...


1999 Land Rover Defender

PostPosted: Wed Sep 13, 2017 5:02 pm    Post subject: Reply with quote

She'll cope Richard - thanks for the update.
__________________________________
The ex-Difflock Ambassador to Naples, Sir Nightbar DCJC DFS and 2 bars.

Plant a tree for the Difflock 3
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** GED **
Off-Road Guru


Joined: 18 Jun 2014
Odometer: 1939
Location: Scouser



PostPosted: Wed Sep 13, 2017 10:36 pm    Post subject: Reply with quote

i had a moment like that with a CB550 fitted with bellmouths on the 4 x carb inlets.

wouldnt run at full power till after a few years of owning it i was coming home from a gig in the freezing cold and closed my legs tight onto the engine for warmth.

bike took off like a rocket.

the bellmouths were deflecting the air away from the carbs....

__________________________________
the other co-founder of the DCJC

Member of TEAM CHAOS
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