1.8 Zetec very low on power
 

We have refitted the zetec into the 100E for another season of 1/4 mile racing. We done a few mods over the winter which we thought would get us into the 15's as it was running very low 16's last year. We were right in assuming it would get us out of the 16's, it's now running 19's and absolutely gutless. We fitted a smaller crank pulley and vernier cam pulleys. Nothing else was done. It sounds ok, no missing or smoking but just got no pull at all.
How do we ensure we got the cam pulleys on properly as with no keyway they could be out a tiny bit? Would this make that much difference as they're obviously not a long way out, if ,any as the valves clear the pistons?
Thanks for any help in advance.