[blykins]

It comes down to knowing exactly when the lifter is on the base circle.

With larger cams, even at TDC, one lobe could be starting to swing up.

When the exhaust valve is starting to open, you know without a doubt that the intake lifter is on the heel of the lobe because you can't have the intake valve open when you start the exhaust stroke. On the same token, when the intake valve is starting to close, then you know the exhaust valve is shut because you're on the compression stroke.

I use the EOIC method on every engine, no matter what. When you get proficient at it, then you can run more than one valve at a time, because the intake valve on one cylinder may be starting to close, while the exhaust valve on another cylinder may be just starting to open...so you can snag them both in short order.