LA 318 advice

273 said
Overlap is the greyed out triangle in between. Moving the lobes closer together (tighten lsa) and or increase duration gonna increase that overlap triangle, rough idle.

If you say keep lsa at 108 then decreasing duration will be the only way to reduce overlap which is basically what you want small ish cam on a relatively tight lsa. Earlier intake valve closing point.

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No it won't. As long as he keeps duration down, it will not. If he uses something like 216 @ .050 on a 108, he'll have a barely noticeable idle in a 318. You telling him that is gonna scare him away from what he needs. All slant 6 cams are ground on 108 and 109 LSAs. Do they idle rough stock? No.