I went and dug up what I know about HRG last night.
>From 'Improve & Modify MGB', by Lindsay Porter & Dave Pollard, published by
Haynes. Page 147:
The HRG alloy crossflow head, originally made for the MGA
series, never really caught on, although in principle it offered many
benefits over the standard head. On the standard head, the inlet and
exhaust ports are on the same side, which means that the inlet ports
have to be siamesed. Also, the centre two exhaust ports have been
joined together. The HRG design gets away from multiple ports and, as
can be seen here (2 photos), the inlet ports are now separate and on
the side of the spark plugs. Although the HRG company ceased
production some time ago, the heads are being manufactured once more
by a company who have bought the pattern rights. The 'new' head
achieves what the old originally failed to do, it actually improves
performance!
The blurb neglects to mention the name of the company who bought the
rights.
James
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