I'm trying to understand the production history of the 1147cc Herald engine
but I'm running into incomplete and conflicting information. Can anyone
shed some light on this?
Here's what I know:
The 1147cc engine used in the Herald 1200 produced 39 horsepower, had a
single 30mm Solex carburetor, 8:01 compression, and a mild camshaft.
The engine used in the Herald 12/50 produced 51 horsepower, had 8.5:1
compression, and used used the same carburetor and camshaft.
The Spitfire Mark 1 had twin SU HS2 carburetors, 9.0:1 compression, and a
hotter camshaft to produce 63 horsepower.
The Spitfire Mark 2 got a new exhaust manifold and a higher compression
ratio (9.75:1? 9.5:1?) which gave it 67 horsepower.
At some point the base Herald engine was increased to 48 horsepower with
8.5:1 compression.
What I can't figure out is when this change (39->48hp) happened.One source
says it happened at engine #GD001, one says GA80,000, and another says
GA190,000. What were the other differences between the 51, 48, and
39 horsepower engines? Did the valves get bigger? Did the exhaust manifold
change? Rimmer only shows one part number for the manifold gasket so I
don't think the port size changed but who knows.
Thanks,
-Erik
--
Erik Quackenbush, Midwest Filter Corporation
1-847-680-0566 http://www.midwestfilter.com
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