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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Valve Springs
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<blockquote data-quote="Monkeypants" data-source="post: 113764" data-attributes="member: 2708"><p>When Terry Prince and Fritz Egli Jr used the Mercedes Formula 1 Cam development program loaded with Vincent data, it showed no power advantage in lifting beyond .440" at the valve. This was a bit of a shocker to Terry as he was always a believer in getting the highest lift possible. The program indicated a lower rpm for valve float at .5" than at .440", which is logical. In any case, it gave .440" with radiused followers as the maximum ideal lift for performance in a Vincent engine. Those are big valves that Irving plunked in there!</p><p>Of course using a higher lift like .5" would also shorten valve train life greatly. .440" might be trouble enough in this regard, time will tell. With the curved followers everything looked happy at 1500 miles, cam and follower surfaces just starting to polish up.</p><p>The max HP rpm figure given for the .440 lift cam was 6500, which is about 1000 past where one can safely go with standard type crank and cases. So even to fully utilize that much cam one needs to think about a Picador type crank and some better cases.</p><p>I believe Mike Hawthorne's Flash engine broke up into many pieces recently, not sure what his crank type is, or what the cause was. I can guess that very high rpm was involved!</p><p></p><p>Glen</p></blockquote><p></p>
[QUOTE="Monkeypants, post: 113764, member: 2708"] When Terry Prince and Fritz Egli Jr used the Mercedes Formula 1 Cam development program loaded with Vincent data, it showed no power advantage in lifting beyond .440" at the valve. This was a bit of a shocker to Terry as he was always a believer in getting the highest lift possible. The program indicated a lower rpm for valve float at .5" than at .440", which is logical. In any case, it gave .440" with radiused followers as the maximum ideal lift for performance in a Vincent engine. Those are big valves that Irving plunked in there! Of course using a higher lift like .5" would also shorten valve train life greatly. .440" might be trouble enough in this regard, time will tell. With the curved followers everything looked happy at 1500 miles, cam and follower surfaces just starting to polish up. The max HP rpm figure given for the .440 lift cam was 6500, which is about 1000 past where one can safely go with standard type crank and cases. So even to fully utilize that much cam one needs to think about a Picador type crank and some better cases. I believe Mike Hawthorne's Flash engine broke up into many pieces recently, not sure what his crank type is, or what the cause was. I can guess that very high rpm was involved! Glen [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Valve Springs
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