Lionel Legacy GP30-Should an MTH Z-750 provide enough power for smoke?

From what I recall the Z750 puts out 21v, Lionel sez not to use over 18v.  If that is wrong or has been updated someone will speak up I'm sure.

I have this engine also powered by a z1000 and it too is a very weak smoker.  I've already sent one back because of this and the replacement is weak also. It seems that you need to fill the smoke unit to overflowing to get any smoke at all. Blowing a puff of air down the stack sometimes helps but I've just resigned myself to the fact that these units are poorly designed

When I got mine the first time the trough or whatever you call the plastic part between the exhaust stack and the smoke unit was loose and not even lined up with the hole. This caused me to unknowingly charr the batting because no smoke fluid had reached it.

Nice. You pay $500 for an engine and that's what you get.