The cam you have is fairly mild as far as lumpy cams are concerned.The figures he has given you are advertised figures which means they are the opening and closing points for the valves.The duration at 50 thou opening is 216 deg which is what some cam grinders give for all there specs.The other durations he has given are opening and closing durations.Lets start with the inlet which opens at 26deg btdc and closes at 68deg abdc then add 180 deg which gives 274deg duration.To work out the lobe centre line we halve 274 to get 137 which we add to the inlet opening of 26btdc which we really take off to get 111deg atdc centre line(peak lift) for the inlet.We then do the same for the exhaust which opens at 70deg bbdc and close 26deg atdc then add 180deg to get 276 deg duration.To get the centre line we take half of the duration(138) from 26 atdc to get 112deg btdc centre line for the exhaust.To work out the lobe seperation we then add together both the centre lines 111 and 112 to get 223 then half that to get 111.5 deg lobe sep.All this info comes in handy when dialling in cams. Grape Ape Drag Racing have a look at this site for some cam info.Go to the camaro build up then valve train and then scroll down.
There also some good stuff under technical articles on the site directory.
Ryan Ottens wrote:
hey list,
i just bought a lumpy cam for $30 the other day.
now i finally got the specs back of it today.
but got no fricken idea on what most of them mean.
all i know is the degree of the cam vaguely.
this is what ive gottiming -
open: 7026
close: 2668duration -
Inlet: 274 (the degree of the cam?)
Exhaust: 276at 50thou 216 (wtf?)
anyways this is what ive been told.
could someone please say 'decifer' this language and tell me what it means,
and also like how lumpy is it etc etc.thanks again,
ryan_________________________________________________________________
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