d15b2 lsi head,d15z1 vtec bottom end....running lumpy help!!

[tommib]

can anyone help,i'm new to d15 engines, i've just put d15z1 bottom end in my 1.5lsi civic 1995(d15b2) i was told it would be lower compresson...its running lumpy at the min does anyone know anything that might help or give me a better idea???? everything else is standard lsi..............