EMERYSON HEADS

[David Kemp]

Enjoy the pictures attached of these heads designed by Emeryson for a Jowett based formula one engine.

[Forumadmin]

I have enjoyed. Any chance they will be operational?

[David Kemp]

The plan is to get them running, just need to find an engine! If anyone has any information on these heads I would love to hear from you.
Your advice could speed up the process of getting them running.

[ian Howell]

From the pictures, it looks as if the valves are a bit special and that they have been used so presumably also the heads, which implies that SOMEWHERE there is/was a modified engine / crankcase.

That being the case there would have to have been a modification to the front end of the engine to give an exposed toothed belt pulley to drive the camshafts. With the required two-to-one reduction ratio required, that pulley would have been VERY small!

Might that cause excessive wear to the belt due to the greater flexing?

[Andrew Henshall]

Here is the photo that I posted elsewhere on JowettTalk last year showing the cam drive system that was set up in Australia using these heads (designed by Paul Emery) on a standard crankcase.

These same heads ran on the dyno at Emeryson Cars Ltd in the UK on three separate engines before the project was abandoned due to crankcase failures.

Regards,

Andrew

[David Kemp]

John of Sydney , Australia kindly phoned me to give me some history of the heads. In particular where the crank cases cracked. His information was second hand, so can anyone verify that the crankcases cracked around the valve follower covers? His advice was to weld up the redundant valve areas to strengthen the area.
Sounds logical to me. Made me think of using the void under the tappet cover to increase water supply & flow. All comments appreciated.

[Andrew Henshall]

Hi David,

Regarding the crankcase failures that Paul Emery suffered on the dyno: the engine in the Wylie Javelin special produces at least 120 bhp and very "robust" torque reliably using a very high compression ratio and 14 psi boost pressure. These two factors combine to generate very high cylinder combustion pressures compared to a standard Javelin engine. The Wylie Javelin engine proves that it is possible to solve the crankcase failures that occurred when running the Emeryson heads. The "secret" is suitable modifications to the engine as follows: you need to run special tappet covers and a "girdle" between the sump & the crankcase!

The tappet covers are machined from 12mm aluminium plate. These strengthen the top face of the crankcase and thus provide better resistance to the tensile forces created by the high combustion pressures present with the Emeryson heads. I conclude that the crankcase failed at low dyno hours simply due to exceeding the tensile strength of the material in critical areas. Of course the fact that the large open area below the thin steel tappet covers would have been "lozenging" between firing strokes on adjacent cylinders would have also been a factor in the failures. This simple modification addresses the areas where the crankcases failed when running the Emeryson heads.

The engine "girdle" is also machined from 12 mm aluminium plate. It strengthens the bottom face of the crankcase to provide better resistance to the tensile forces created by the high combustion pressures present with the Emeryson heads. This ensures that the crankshaft is well supported while maintaining main bearing clearances, in order to avoid bearing failures.

Joe Caudo runs both these mods (plus many others) on the naturally aspirated engine in his tarmac rally Jupiter, and it produces plenty of bhp reliably and will rev over 6000 rpm all day long.

The Series III crankcase has cast in ribs which strengthen the main bulkheads in the crankcase to improve rigidity in order to provide improved main bearing life, but they also contribute to crankcase strength, and thus a Series III crankcase would be essential to aid durability when running the Emeryson heads.

The standard Jowett Jav/Jup con rods will be marginal at best with these heads if you intend to run high rpm, and so a set of forged rods would be a worthwhile investment; perhaps Carillos.

Of course, you will also have to do all the mods that the JCCA has developed over the years in order to get the engine to be durable; crank bearings, oil pump, etc, etc. The machining of the cylinder liners will be critical if you are to avoid ovality (& hence piston scuffing), and the setting up of the liner protrusion plus the selection of the two critical gaskets (bottom of liners and head gaskets), if you are to achieve reliable sealing at the head gasket.

Cheers,

Andrew