Cylinder head aluminium v Iron

[tomcotez]

I am interested in the subject of compression, by my calculation a 26cc combustion chamber would give a CR over 8:1 which seems high for an A7?

I have a Ricardo head and can confirm that it makes power and looks nice, although the engine is fairly harsh even with a new bottom end.

[dickie65]

Hi Roger,
I think its time to do a volume check on both my 9E heads.
I know one was skimmed in the 1990s with the minimum taken off it.
The other head is a more recent find but the 9E block that came with has still got its diamond marks on its top face although this head will need a light skim.
The engine also runs well with a Ruby HC head.
I have a perspex sheet and a burette in the shed from a modern engine build.
I always understood you could never get too much compression with the Austin side valve design without making the valves smaller with less lift to make the chambers smaller.

[Rogerfrench]

There are many posts in this forum and its predecessor that complain of harsh running caused by too much compression. Even fitting 37 heads to 2-bearing engines has given some people problems.
However, you're right if you mean that it's difficult to get high compression and good breathing from a sidevalve. Without a Blower, that is!

[Bob Culver]

The Ricardo head is certainly curious. Seems to break all conventions, including Ricardos. Some other makes have a deepend area leading to the inlet but not the exhaust!

[Tony Press]

I have a vague memory that the so called 37 head was a Ricardo type and Ricardo challenged Longbridge for infringing their design - or am I talking complete rubbish  

[Bob Culver]

Hi Tony

The 1937 head is the classical Ricardo patent layout. When octane was very low it enabled a cr increase and prolonged the use of sv engines which, with long combustion paths were otherwise very limited to cr and hence efficency. Ricardo took action against makes who adopted it early. The existance of another with specifically that name is confusing, esp when, apart from a squish area, it seems not to comply with the Riacardo norm.! .

[Malcolm Parker]

I don't know about the technicalities of the Dave Dye Ricardo head, but my experience is that they are equally suited to engines of all states of tune.  My RL saloon has one on a mildly tuned engine and runs more smoothly than it has with any other head, as well as having useful extra power and flexibility.   They are the preferred choice of most who compete in Austin 7's.  Unless you are VERY proficient at modifying standard heads it would seem illogical to go any further than the Ricardo head.