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just wondering if someone can explain to me what the different types of cams mean. ie 30/70, 40/80. what do the numbers represent and how do they perform? thanks guys. any info appreciated.
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30/70 means the inlet starts to open at 30 degrees before top dead centre and closes fully at 70 degrees after bottom dead centre.A 40/80 means the inlet opens starts to open at 40 degrees before top dead centre and closes fully at 80 degrees after bottom
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Hi Guys.
To add to what hq ss has said, to convert these figures to the more common 'advertised duration' used these days, all you do is add the 2 numbers together & then add 180.
e.g, the 30/70 cam when added together becomes 30 + 70 = 100, then 10 |
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The true measurement of a cam is done at 50" tappet lift.Advertised is normally done at around .004" tappet lift(but not by all brands ,so you end up with differant advertised durations). For a more acurate comparison of cams you have to graph them. I hav
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Dr Terry
What is a better grind than a 30\70 or a 40\80
Cheers Alan
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Hi Alan.
There is no one-line answer to that question, it's horses for courses. With cams, bigger is not necessarily better, it depends on your application. Camshafts have to be matched to head, carburettion & gearing etc. If you want good low-down to |
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