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Comet cam and timing maks

derek

Well Known and Active Forum Website User
VOC Member
When fitting an unmarked half time pinion to a twin, we know to line up all marks and with back pot at 4 deg before tdc fit half time pinion! This means that the front pot is 54 deg before tdc. There for what is the correct proceedure for a comet? Is it to line up marks with the pot at 54 deg and fit half time pinion? ( I can not find this information anywhere )
Please don't advise me to check opening and closing of cams with a clock gauge, as I have Gary Robinson cams and the figures do not tie in. Derek.
 

clevtrev

Well Known and Active Forum Website User
VOC Member
When fitting an unmarked half time pinion to a twin, we know to line up all marks and with back pot at 4 deg before tdc fit half time pinion! This means that the front pot is 54 deg before tdc. There for what is the correct proceedure for a comet? Is it to line up marks with the pot at 54 deg and fit half time pinion? ( I can not find this information anywhere )
Please don't advise me to check opening and closing of cams with a clock gauge, as I have Gary Robinson cams and the figures do not tie in. Derek.

No use the same as the twin, you are timing No 1 cylinder, not No 2. So as you`ve only one cylinder on a Comet, that`s No 1.
 

nkt267

Well Known and Active Forum Website User
VOC Member
Please don't advise me to check opening and closing of cams with a clock gauge, as I have Gary Robinson cams and the figures do not tie in. Derek.
Point taken Derek but can you be certain that the cam lines up with the cam wheel as per factory spec?..John
 

timetraveller

Well Known and Active Forum Website User
VOC Member
Ken is correct. You just cannot trust timing marks unless you have a set which have been previously tested. Set the system up so that the height of the exhaust closing and the inlet opening are the same at about four to six degrees before top dead centre. It is a bodge, particularly if you say that the cams do not have standard timing, but it will work OK until such time as you can do the job properly
 
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