nap times and night sleeping

[sleepymama]

Just doing a quick check on what other mums think. You may have seen my threads about 3am/4am waking and sleeping through the night.

My question is whether long naps will affect lo's going through the night. Have been trying to follow babywhisperer and have succeeded in getting ds (16 weeks) to nap for around 4 1/2 hours per day (has only worked for past 2 days mid you!) However, he is now waking more frequently during the night. Before long naps he was a nightmare during the day seeming grumpy and still tired.
Now I have to wake him after 2 hours!
How long is long enough for naps, in other mnetters opinion. Especially those of you whose lo's sleep through.I know each baby is different but just wondering really......

Have now realised he is either teething or has viral bug. Today cheeks still red, raised temperature, very bad nappy rash (something he's never had), diarrehoea and very very irritable.
Have given him calpol and took him to the docs.
Was in with the doc for less than 5 mins when she said 'oh its just a viral bug - just keep feeding and give him calpol' and sent me on my way!!!!! Is it teething ?

Have also changed his dummy to one with an orthodontic teat, something he didn't take to kindly. V.funny though watching his disgust and ranting on with said dummy in his mouth and then eventually falling asleep . Will still keep the other dummy close by tonight though.