Here is a story about cold starting the R-2800s on a Howard 350, same company and chief pilot of the Convair "Bar" story.
One morning in Gunnison Colorado I was a new hire on a Howard 350. We had spent the weekend and the temperatures at night was really cold, hell, it was still in the teens that morning. We got to the airport Monday morning and as a new, young exuberant co-pilot I wanted to make a good impression to my seasoned, elder, senior Captain (he was about 40), if for no other reason than not being able to keep up with him drinking Scotch over the weekend. So I asked him if he wanted me to have the FBO bring out the engine pre-heaters.
"Nah, don't need 'em." He was a man of few words as well. So we get into the cockpit with the intention of starting the engines, warming them up before the passengers get there. "Clear on two" he calls and engages the starter. I reply clear, thinking a bit late for that as he has already hit the starter. But as I was looking at the engine, nothing was happening, looked back into the cockpit, yup the starter was still engaged, so I look back out at the engine. I could hear the starter groaning and then very, very, very slowly the prop started to turn. "It turning yet?" he asked.
"Yes sir, it is moving, but really slow." I answer and he says, "Let me know when fuel starts pouring out on the ramp". 'Let me know what!' I think, "Yes sir I answer. Well the prop is moving a little better and by now it has turned about three agonizingly slow times and I see fuel start pouring on the ramp. "Fuel is coming out on the ramp now." I called out.
"K" he says and turns on the mags. BANG, POP, POW, BANG, COUGH, COUGH, BANG, POW and flames start shooting out of the stacks, the front of the engine, hell flames are coming out of everywhere, as it keeps banging, popping and coughing. Pretty soon to my amazement, it actually starts running, all the flames go away and I don't have to call the fire department.
So I look at him as he is getting ready to start the left engine and I say to him, "Okay, I figured out how to start these things when cold soaked, catch them on fire and the heat of the fire warms the engine up enough to start."
He just looked at me and hit the left engine starter.