Why the hell did you use the 1.6 block? it's more than likely an oiling issue. The non-vtec oil pump is probably not pushing enough psi for VTEC engagement. It could also be a multitude of other problems. VTEC blocks and non VTEC blocks differ in several ways. Not to mention the D15B's rods are likely beefier than the non VTEC rods. It could be a lot of things though. What intake manifold are you using?