F303 cam

tylerrocks said:

ok guys, I have all the top end components for my engine build. Speed Deamon 650 mech.secondaries, Edelbrock RPM (non air-gap) intake, GT-40p heads, 1.7 roller rockers.

I found a good deal on a nicely built shortblock that will allow room to grow. It comes with an F303 cam, now I'm pretty blind when it comes to cam specs, but it looks a little big. What do you guys think? I also have a freshly ground stock cam.

The car is a daily driver soon to have a T-5 and 3.73 gears.

Tyler

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tylerrocks said:

Thanks alot guys. So I take it that this cam would make an OK street cam, right?

Can someone set the record for me how the rockers effect lift? I know stock ratio is usually 1.5 and 1.7 simulate more lift. Can someone give me the math? . I've tried to reason my way through it but I always come up with numbers that are a little high.

Tyler

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180 Out said:

Well lessee, brushing off the ol' high school algebra (which is a lot of brushing, considering I'm Class of '72): valve lift = lobe lift x rocker ratio. Let "a" = valve lift w/1.5 rocker ratio, and "b" = valve lift w/1.7 rocker ratio. This means:

a = lobe lift x 1.5 and
b = lobe lift x 1.7

Next,

a/1.5 = lobe lift and
b/1.7 = lobe lift

Since lobe lift is the same in both equations,

a/1.5 = b/1.7 and
b = 1.7 x a/1.5

Since 1.7/1.5 = 1.13

b = 1.13 x a

So, for example, if you've got 0.500" valve lift with a 1.5 rocker ratio:

b = 1.13 x 0.500
b = 0.565

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