F303 cam

[tylerrocks]

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

 

[10secgoal]

That cam isn'y really big at all. I have an X-cam with a tin more lift, and it was streetable, too. i have the f cam now and it idles and drives fine. No where near the line off streetability I don't think in anyones mind.

 

[tylerrocks]

alright man, good to know, thanks. Happen to know the specs on a stock cam?

Tyler

 

[tylerrocks]

Can I run the 1.7 rockers on the F303 without valve clearence problems?

Tyler

 

[RED92VERT]

You should be fine with Piston to valve clearance, but you should upgrade your valvesprings if they are stock.

 

[rhyno9]

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

The F cam seems to be the cam of choice for forced induction.

 

[D.Hearne]

I'm running a Z303 in my 331 with 1.7 rockers. Idles at 6-700 rpms with the 3x2 setup. Pulls from 1500 to 6500+ with the dual plane 3x2 and Canfield heads. No piston to valve clearance problems, but it's got SRP pistons. These are flat top, two valve reliefs, .003 deck clearance, heads were milled .060 and the gaskets are .043 thick.

 

[tylerrocks]

How dose the Z303 cam differ from the F303?.... Man, I really gotta learn about camshaft geometry.

I have SRPs also, two valve reliefs, 0 decked, GT-40p untouched heads. I havent got gaskets yet.

Tyler

 

[57fairlane]

The valve timing events at .050 are 4, 42,52,-6? IVO/IVC/EVO/EVC

either way its 226/226 on a 114 lsa with .512 lift.

It has no overlap at .050 and not a ton of lift. I cannot imagine you having any piston to valve issues.

 

[D.Hearne]

The Z cam has got .585 lift with 1.7 rockers and the duration at .050 is 228.

 

[tylerrocks]

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

 

[180 Out]

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

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

 

[ashford]

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

hey don't confuse the guy arithmitic works too.
well the ratio means you get 1.7 times lobe lift to the valve. and cam valve lift is generally specified considering the stock rocker ratio. just to set things straight 1.5 is sbc, sbf is 1.6 stock except clevland 1.71. just to comfirm your algebra ill use 1.5.

if you know the valve lift divide it by the ratio.
.500/1.5=lobelift(.333333333)
well now you know lobe lift, multiply it by 1.7
.3333333x1.7= .56666666666666666

hey you rounded your 1.13 a little too close, not that .001 will make much difference though

so .512/1.6=.320 lobe lift
.320lobe liftx1.7=.544 valve lift with 1.7