ET: Engine (Twin) 1947 Series ‘B’ Cam Pinions

Rob H

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I have heard that Vincent made cam pinions out of different material and some are not as good as others and can fail.

Would this be the case for an early B Rapide? and is it recommended that they be replaced with a modern equivalent. together with the large idler to replace the aluminium one?
 

vibrac

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Certainly replace the alloy idler although I think they got a bad press over the 'lean years' when Vincents were run into the ground and oil was relatively expensive. As were the steel idlers which were available for racers, I remember wanting one when I started racing my twin in the sixties and they were £50 each, see what that is in inflation terms now!(£951) The alloy ones did last for years if looked after( Tony Rose had one) anyway you cant get alloy idlers now and if they do go they certainly make a mess so its a no brainer
 

Nigel Spaxman

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On the early Bs the idler was made of bronze. It is supposed to be failure prone like the alloy one. I have one on the wall of my shed along with an aluminum one. Both of those appear to be in perfect useable condition but I fitted a steel one to my bike in order to avoid problems.
 

chankly bore

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If you are planning to actually ride the bike you must also replace the original alloy/ steel large idler boss. They were a good enough design for production and use 70 years ago, but unless you have a low miles machine with a complete known history this component will either be separating, have separated, or will flog out the first time the motor gets really warm. The same remarks apply to the magneto pinion / A.T.D. and the Twin alloy steady plate ET161.
 

Rob H

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If you are planning to actually ride the bike you must also replace the original alloy/ steel large idler boss. They were a good enough design for production and use 70 years ago, but unless you have a low miles machine with a complete known history this component will either be separating, have separated, or will flog out the first time the motor gets really warm. The same remarks apply to the magneto pinion / A.T.D. and the Twin alloy steady plate ET161.

Thanks for the advice, The motor has not been run for maybe 50-60 years, mileage is unknown. I plan to do a lot of mileage with the bike so any tips or advice on what to check or replace with new materials / parts would be welcome.

What is the problem with the steady plate. I thought if this was a good snug fit it would be OK?
 

chankly bore

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Non-VOC Member
If the steady plate is still flat that's a good start. The hole for the large idler spindle is designed to be oversize to facilitate adjustment of mesh, all other holes should be snug. If this is so, all well and good. Many are bent and disfigured by loose spindles and heroic attempts to secure them.
 

Rob H

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VOC Member
Sorry to ask again but back to the original question, Would I need to replace the cam pinions if these are still in Ok condition?
 
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