How does a cams LSA affect idle?

[nickthegenius]

I can't remember how it works. Does a tighter or looser lobe seperation angle make for a choppier idle?

 

[8yourZ06]

I can't remember how it works. Does a tighter or looser lobe seperation angle make for a choppier idle?

basically..the more valve overlap you have the choppier the idle

 

[nickthegenius]

Ah...the overlap. I was thinking that LSA played a role in it, too. Reason I was asking is that I noticed that VT Engines has like a 108* LSA and my Comps are 113* and just got me thinking.

 

[Ottomatic]

Valve overlap can be calculated by adding intake and exhaust advertised duration, dividing that by four, then subtracting the LSA. So LSA DOES play a huge role in the idle quality of a cam. Make sure you use advertised duration, not @.05"!

Hope this helps.

 

[Ottomatic]

Bah, forgot to mention, after you subtract the LSA, multiply the number by two and that gives the degrees of overlap.