d_och23

whats the different between advertise duration and duration at .050 and what does it mean? and what would i want to look for if i wanna make it down the 1/4 quicker?

JD1969

Duration at .50 is what you use to compare one cam to another, comparing advertised is not accurite. A cam alone will not help you much, we need to know more about your car, give as much detail as possible, ie enine, trans gear and what other mods you have.

FullAuto

Advertised duration is a BS number the cam companies come with by however they feel like measureing it. Duration @ .050 puts them on a level playing field for comparision and is the number you should be more concerned about. But these numbers can't be weighed too heavily upon because even if they are identical to another cam, that doesn't mean they are the same at .100, .200, etc. If you were to look at a master cam catalog, you'd see all kinds of ramp rates for similiar durations @ .050. The timing events will be all over the place too in comparision. It's a very difficult science and a huge majority of people are just shooting in the dark when they choose cams.

tinman

Then there is a school of thought that says if the lift is under .600" none of it really matters.
That .050 number is so that you can see how aggressive a given cam is going to be compared to others.
I never really much attention to an advertised duration anyway......

d_och23

well i have a 306w/ upper and lower gt40 intake bbk 190 fuel pump and fuel reg. rebuilt heads w/ dual springs, bbk shorty headers and right now i have the E303 cam. i know i need heads but money always seems to be an issue. but when i decide to put my 351w later on i wanna look for something pretty radical but w/ no power adder. so what do yall think can help me out?