Joined: Jan 2019 Posts: 1,482 Threads: 17
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Location: Bala North Wales
Car type: 1933 RP Standard Saloon
"David, if our railway station was still open I'd hand a spare wedged head over to the guard. After a long passage through the branch lines of wales it would reach you at Bala station in due course. "
Thank you for that kind thought, Steve. Alas, our nearest railway station is Wrexham! However, if you are serious, there are ways of collecting the head. The Seven has been down your way before.
I made enquiries of Surelock as recommended by Oxford Jack, and Nick Hood has estimated that to seal my head including all the relevant testing would be about £200.
Joined: Aug 2017 Posts: 862 Threads: 16
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Location: North Yorkshire
Regarding the wedged low compression head, the machining alters the shape of the combustion chamber significantly. The final shape depends on the angle that the machining is done at, also the amount that is taken off. The three wedged heads that I have had were machined on a lathe, and all are different. The head that was on the Pytchley was machined with 4mm difference one side to the other, I think this is about as big a wedge as you can probably go. The thickness of the castings vary so there is always the chance that if you go too far, you may break through the head of the combustion chamber into the water jacket. Our technique was to make several cuts and keep an eye on the shape of the combustion chamber, stopping when it looked okay. All very unscientific. It is amazing how the shape of the chamber develops after a certain point. The Pytchley head ended up with a combustion chamber volume of 23.2 cc, according to my calculations, which gives a CR of about 7:1 with the gasket. The more the angle of the wedge, the more you need to open out the stud holes in the head.
This head is going on a new engine I am finishing off for the Ulster, it will be interesting to see how it compares with the Ricardo head fitted on the present engine.
Joined: Aug 2017 Posts: 102 Threads: 3
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With the low comp. head on my RF saloon, I had 30 thou and 50 thou removed to "wedge" it. It now gives lively performance and the stud-holes still clear the studs.
Joined: Aug 2017 Posts: 3,247 Threads: 360
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Is the Ricardo repro accepted by VSCC? I thought the whole point of the wedged heads were keeping to original, and in absence of Ulster heads to use, having no other easy vintage options?
Joined: Aug 2017 Posts: 862 Threads: 16
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Location: North Yorkshire
The Ricardo head is of a type that was available in period and is accepted bt the VSCC. Most Austin 7's competing in trials and speed events are using them. They are available with either 18mm or 14mm plug holes.
I would not spend £200 having a duff wedged LC head repaired when for a few quid more you could have a brand new Ricardo head.
Joined: Aug 2017 Posts: 1,535 Threads: 90
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Location: Monmouthshire
Nick, many thanks for passing on such obscure but enormously helpful information. Oh where would we be without the forum!
Joined: Aug 2017 Posts: 1,535 Threads: 90
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Location: Monmouthshire
Ah Nick, are you a philosophy lecturer as well as a skilled Seven strangler? Sounds a bit like Schopenhauer to me.
