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1969 Mercury sprocket sizes

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Hello,

Does anyone know the standard number of teeth for the engine and gearbox sprockets on a 1969 Mercury? Over the years I have played around with various ratios and have forgotten what they originally were. Also were the stardard ratios chosen to best suit the engine or were there, even back in the 60's, concerns about noise at test speeds?

Thanks in anticipation,

Mick

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Engine 21T, Gearbox 19T. Going by memory, but reasonably sure. Designed to get maximum speed at max power rpm. Some people over-gear them to keep the cruising rpm down a bit, but you would then only get top speed downhill or with a following wind. When they were new, noise abatement wasn't a concern. Max speed for road test most certainly was. Gordon.

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Previously Gordon Johnston wrote:

Engine 21T, Gearbox 19T. Going by memory, but reasonably sure. Designed to get maximum speed at max power rpm. Some people over-gear them to keep the cruising rpm down a bit, but you would then only get top speed downhill or with a following wind. When they were new, noise abatement wasn't a concern. Max speed for road test most certainly was. Gordon.

Well your better with a 22T Engine and 19 T On the box

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Of course a 22T engine sprocket is better for a given definition of better. But so is a 21T sprocket better for a different definition of better, as alluded to in my original post. With a 22T sprocket in still wind and level track, you would find that your top speed is the same in 3rd as it is in4th gear. My Atlas runs a 21T engine sprocket and itsuits it well. But others will have different experiences and preferences.

 


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