Walter and John are absolutely correct. DON'T do it. I was taught that method and it worked fairly well for 20 years when suddenly.............
I was starting a heat soaked IO 520 at Fitzroy Crossing and it was being cantankerous so I stopped the starting procedure ,flooded it a bit more and then continued using the starter. It did a small backfire and the fuel guy got real excited. He grabbed the extinguisher and poured foam into the engine compartment.
The fire started in the inlet manifold and the backfire ignited the fuel fume soaked air filter. 24 hours later sporting one brand new air filter we were on our way. We were very lucky.
Once again it was a case of OWTs being handed down by people who didn't know better and like me had got away with the method for a long time.
I now use the Cessna Pilots Association method for hot starts. It's not only safe but it's much more reliable.
Cheers RA