thats alot of info that made me go , ,
i'll trust your word, i think you know a thing or two on cams sportside.

 

It does. Look at EVC. It uses the ECL to calculate the closing point of the exhaust valve.
112LSA + 4 = 108ICL, 116ECL
112LSA + 0 = 112ICL, 112ECL
112LSA - 4 = 116ICL, 108ECL

 

to that...haha but i dont think half of us will need to know that kinda information for our set ups. maybe if we are trying to be AT the limit for every paramter in the valvetrain with the biggest cam etc. all that stuff just goes right over my head. too many numbers and acronyms

 

so numbering those cams 1-3, i can say that cam 1 closes its Exhaust valve later than cam 3 and begins the intake event later as well and vice versa?

 

Must you ***** my thread with your presence!!!!! Dont reply...pm.

 

Nope. Cam #1 has 4* of advance with the given (112LSA). All have the same 112LSA. The only difference between all of them is the ICL/ECL. Cam #1 being 4* advance has all of the events 4* sooner than Cam #2 and 8* sooner than Cam #3.

Remember, Cam #1 has 4* advance. Cam #2 has 0*. Cam #3 is 4* retarded.

When you adjust ICL/ECL all of the events change in the same way. There's only two ways to go... Sooner or later.

When you keep ICL the same, but move the LSA, ECL will change.

112ICL , 114LSA, = 116ECL
108ICL , 115LSA, = 122ECL

 

You gotta give Beau credit tho... This is a lot of bullshit to try and understand.

 

in one ear and out the other......

 

****! So i was *** backwards. So with cam 1, you would have to worried about the intake valve smacking the piston and on cam 3 you would have to worry about the exhaust valve hitting the piston due to the fact that there would be a later closing of the exhaust valve? So thelower the numerical ICL/ECL value, the closer it will be to the valve itself? (and here is where you say, "well yes in some cases but..." )

 

I know where you're at... I've been there... ****, I'm still there.
Your getting it Beau, but your best bet is going to be playing with some VE calculators and seeing what does what.

Let's try something. Starting fresh here. You got a 5.3L shortblock with stock heads, truck intake, pacesetter long tubes reduced to 2.5'' duals. Shove a 3,000 stall in it with a set of 4.10s and a eaton. Check out the X-E line of Comp lobes and decide on a 220/220 profile. Call up Comp and tell them you want it on a 110LSA with 0* of advance. Remember now, 0* of advance puts the ICL/ECL all at 110*.

So, lets look at the valve events @ .050'' given 220/220 as duration for both the intake and exhaust : 0/40/40/0

Valve Events @ 110ICL
IVO: 0* TDC
IVC: 40* ABDC
EVO: 40* BBDC
EVC: 0* TDC

1.The intake valve opens at TDC (0*).
2.The intake valve shuts 40* after bottom dead center.
-That means the piston went all of the way down the bore (180*), and went 40* back up for a total of 220* of duration.
-As soon as the intake valve shuts, this is the beginning of dynamic compression. Static Compression is 140* after the intake valve shuts [180*- 40*(IVC)] when the piston is at TDC. SCR is the measured height. I'm just throwing this all in so you can grasp the entire concept.
-The spark fires, and throws the piston down. The piston travels 140* (of crankshaft rotation) down the bore and the exhaust valve opens.
3.The exhaust valve opens 40* before bottom dead center.
4.The exhaust valve shuts at TDC (0*).

Okay. Lets throw 2* of advance at this cam. This moves the ICL to 108* and the ECL to 112*. The cam events now are advanced 2*. ALL OF THEM.

Valve Events @ 108ICL
IVO : 2* BTDC
IVC : 38* ABDC
EVO : 42* BBDC
EVC : 2* BTDC

Lets throw this in. How much overlap does this cam have measured @ .050'' specs? Well, if the IVOpens at 2* BTDC and the EVCloses at 2* BTDC, that would be 0* of overlap. Overlap does not change with adjustments when changing advance/retard.

Valve Events @ 112ICL (4* of retard from cam with 108ICL)
IVO : 2* ATDC
IVC : 42* ABDC
EVO : 38* BBDC
EVC : 2* ATDC

Now, lets change the LSA. This requires a new cam of course, but lets add 4* of overlap and we will keep a 112ICL. Every number difference in LSA with the same duration is 2* of overlap. To add 4* of overlap with a 220/220 cam would require a 108LSA.

New cam: 220/220 108LSA/112ICL
Valve Events @ 112ICL
IVO : 2* ATDC
IVC : 42* ABDC
EVO : 34* BBDC
EVC : 6* ATDC

New overlap. 6*EVC - 2*IVO = 4* of overlap.

Another thing to note. Duration and ICL change the intake events. If these remain constant, LSA will not affect the intake side of things as far as valve events go.