S  U  P  P  L  I  E  D    B Y

S  P  E  E  D  E  X

L  U  T  O  N

Standard Austin heads

Early A7’s had a cast iron head with the 18mm plug positioned over the cylinder. This scores poorly against all our three factors. If you do want to use this type for originality reasons always use the later thin gasket, you do get a little bit more compression. It can be improved by opening out the chamber in the narrow valve to cylinder area. Use the later gasket as a template. You can skim about 40 to 50 thou from the face to raise the compression slightly, much more and the plug becomes masked and the raised compression is offset by poor combustion at higher revs. The really early heads had tappings into the chamber with brass priming cups. Slightly later ones had the tappings with brass plugs. I have seen one of these tapped out to take a spark plug with the 18mm holes plugged off. A good modification if the formula or specification you’re working to demands the standard head has to be retained. Like the one pictured, the threaded water strap is often corroded. If not too bad you can helicoil them. It is possible to slide a nut under the strap to bolt the pear shaped branch on.

Later A7’s from 1937 had a cast iron head with 14mm plugs. This head is almost really good. Plug position is a bit too far from the exhaust valve and beyond the centre of the combustion chamber. Chamber design is along the lines of a breathing head with a raised chamber roof and breathing space around and above the valves. The design has tried to keep the compression up as well. Skimming more off the face will increase the compression, 40 or 50 thou is OK for most applications though I have heard of 100thou being taken off. Watch out for clearance over the valves, turn the engine over with a blob of plastacine on each valve to get the clearance, don’t forget to take the gasket thickness into account.

Sports engines had a head that looked similar to the later 14mm head but had 18mm plugs nearer the valves. 9E1 usually is very visible cast into the top. This doesn’t have the raised chamber roof just a simple slope. Later Grasshopper engines had a newer version of the same head in aluminium with an integral water branch. I haven’t seen the chamber shape but the plugs look to be in the same position as the earlier sports head so I surmise the chamber was the same. For completeness and to drool over there’s a picture of the last works side valve head with multiple studs and twin plugs.

ALTA made two aluminium heads for the Seven. The one with the inclined 18mm plugs is novel. I had one of the later (?) 14mm heads and it had a small part of the chamber over the cylinders like the picture at the bottom. I also remember the deck of the head wasn’t very thick and couldn’t be skimmed much and it may have been vulnerable to warping. Plug position is quite good on both types, the chamber shape is for compression with limited breathing enhancements. My other recollection of this was that the water holes didn’t line up very well with the gasket or block holes. It does look good on your engine though if the ALTA logo is picked out in enamel! Although considered prewar ALTA heads were still being advertised at £6-15s by VW Derringtons in 1962.

Not everything about Austin heads is understood, this one just looks like an early standard head from the top. However the plugs are in deep recesses and the chamber is quite a bit different being very deep over the valves and no recess over the cylinder. Experimental?

Whatmough Hewitt were another prewar head supplier. Jack French often said that this was his preferred head. Examples I’ve seen have been aluminium but there was also a bronze head. John Barlow has remanufactured this head in aluminium. Although the one in the photo uses a pear shaped water outlet, John’s has an integral water branch cast in similar to the Ricardo above. I believe these recast heads are available with either 14 or 18mm plugs and low or high compression.

Sporting Motoring Agency was established in the mid fifties closing in the late fifties. It’s parts are denoted by Dante cast into them and along with the head there was a range of other castings, manifolds etc. This head was designed to increase compression, breathing between the valves and the cylinder is restricted. It seems designed for the earlier gasket and has the narrow passage as a consequence. Plug position is good right over the exhaust valve. This head cost £6-7-6d in the late fifties.

Speedex grew out of Dante’s demise. Their castings came from the same foundry that Dante had used. The initial Mark 1 head used the pear shaped outlet. A breakthrough on the design with a Mark 2 having a removable water outlet that was reversible to allow the use of a cross flow radiator. Like the Dante the head has compression and a good plug position. Breathing is better though based on the later gasket shape. Quite a few of the heads don’t have Speedex cast in for some unknown reason. The head cost £4-19-6d with the special water branch an extra 15s.

Contemporary with Speedex, Super Accessories were making their own head under the Supaloy brand. Like the Speedex head this started as a Mark 1 version with the pear shaped water outlet evolving onto a Mark 2 version with the removable, reversible branch. Plug position is good on the edge of the exhaust valve, breathing is good with the raised cylinder roof and the chamber wall taken further back utilising a special gasket (though the normal later ones seem to work OK with them). Famously advertised as ‘making your old saloon go like a Sputnik’ it cost £5-5s complete with the water outlet with an extra 4-6d for the special head gasket.

Also sold by Super Accessories was the LRM head—Lee Racing Motors. Designed and developed by Roy Lee a well known 750 formula / constructor driver in the late fifties. This head has three separate water take offs joined by hoses. These could be reversed but not many still have these now. The head is orientated towards breathing with a good plug position, note how wide the passage is between the valve and cylinder areas. It did have a reputation for warping in the sixties, was this justified or a myth? £9-0-0 from Super Accessories with an extra £2 for the water branches.

Coldwell manufactured heads during the sixties. The only one I’ve seen was an unmachined casting so the characteristics are unclear to me. However the plug position is good and from the picture it seems to be very similar to the LRM.

Similarly Silvertop made a range of heads for various cars in the sixties, they were advertised in MotorSport by VW Derringtons but strangely no A7 head was listed but an ALTA was? I’ve never seen one of these but it does look like a finned Cambridge head without the fins. Plug (14mm’s?) position is good. Previous articles have linked Silvertop with the Aluminium Cylinder Head Company, their product may have been prewar and may have been what the Lotus 3 and Stoneham used. This 14mm plug head seems very similar to one of the Ricardo heads down to the core plug positions and those extra bosses, was one preceded from the other using the same pattern?

A ‘breathing’ head will have room round the back and over the top of the (oversize) inlet valves for them to flow, the combustion chamber roof will be raised between the valves and bore and this will be matched with a radiused edge to the bore—’relieving the block’. Some designs even open up the width between the valves and bore, particularly on the inlet side, with a wider gasket.

A ‘compression’ head avoids any excess volume in the chamber. This head has a close clearance with the back of the valves and may even curve in slightly in between them. Similarly the roof is set to give only a slight clearance on the full lift of the valves and isn’t raised but slopes from the valves across to the centre of the bore.

Note close clearance