Most HO locomotives weighing 15 ounces or more should have about 4 ounces of drawbar force. This equates to 40 easy rolling cars before stall. I usually figure half of this for an average train, 15 to 20 cars, for realistic speeds on a flat track.
General consensus is that cars should not require more than .1 ounce of pulling force. I make my own force gauges, but here is a handy one at a reasonable price. The 250 gram gauge is adequate for HO.
http://www.delta-education.com/productdetail.aspx?Collection=Y&prodID=1973&menuID=
Tuning your cars by reaming the jounals and using metal wheelsets makes a big difference on how many you can pull.
General consensus is that cars should not require more than .1 ounce of pulling force. I make my own force gauges, but here is a handy one at a reasonable price. The 250 gram gauge is adequate for HO.
http://www.delta-education.com/productdetail.aspx?Collection=Y&prodID=1973&menuID=
Tuning your cars by reaming the jounals and using metal wheelsets makes a big difference on how many you can pull.