Hello,
I know I'm resurrecting an old thread (is that considered bad, here?) but I have some related questions/historical info.
I'm not sure of the whole sequence of events - did Canadians play a part in locating the 6-71 as a possible replacement engine for the Valentine? Or not?
Anyway I was just looking at a file I copied from LAC a while back and found this which might be of interest:
"The Canadian model [of Valentine] will be provided with a G.M.C. two-stroke C-I engine, the experimental development of which was carried out at the A.E.C. works under the supervision of the Directorate. After very satisfactory trials, a pilot vehicle with the G.M.C. engine was despatched to Canada towards the end of the year." - Directorate of Tank Design, First Progress Report, covering to Dec 31, 1940
"Some successful experimental trials have been completed with the C.I. engine adjusted to provide increased power and speed. With an output of 150 b.h.p at 2,000 r.p.m., reliability and cooling have not been adversely affected, and a market improvement in average speed across country has been obtained. The General Staff consented to trials in the Service, the results of which are awaited."
The first production G.M.C. two-stroke C.I. engine has reached this country and is being installed in a tank. In view of the successful trials referred to in the preceding paragraph, the second pilot engine is also being installed in a tank for trials at its maximum rating of 165 b.h.p. at 2,000 r.p.m. to ascertain reliability under these conditions."
- Directorate of Tank Design, 2nd Progress Report, covering to March 31, 1941
What I'm trying to get straight in my head is designations for the engine in the Valentine and the Valentine SP aka Archer and what were actually the differences between them.
Despite the above, according to Dick Taylor's book Into the Vally, all marks of Valentine up until late Mk IXs had the engine tuned to output just 138 BHP. And I've seen this first version referred to as a 6-71S which was replaced with a 6-71A (outputting 165 BHP). And in the Archer it was a 6-71M and it's also referred to as a Type 6062. Somehow, GMC (I presume) got it to produce 192 BHP but how they did it I have no idea.
S for Special makes as much sense as anything else... A? M? I haven't a clue.
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