Pretty simple, Pontiac rejects more heat through the cooling system than other engines of the same size. The heat coming off the radiator heats the fuel system under a yellow flag. You will occasionally find some other brands that OH on an oval track, but as long as I've been around oval tracks, building, and racing Pontiacs are the toughest to keep cool. My father followed oval track racing since the late 40s, told me that even back then Pontiacs were prone to overheat with straight 8s and sixes.
I had a 455, the ford was a 351 M, most of the chevies were way under 400 cubic inches. To get same the heat rejection in a chevy you have to go to a 454 in a truck normally to find as large of a radiator as a Pontiac 455 in a car. There are very few Pontiac applications that came with a 2 core radiator
I have no idea of why the Pontiac design rejects more heat than other manufactures designs. All you have to do is look at radiator core thicknesses to see that almost any Pontiac of the same cubic inch size required a larger radiator than other GM cars. I've been through the wrecking yards since i was 14 years old, and you will invariably find that say a 350 chevy has a much smaller radiator that a 350 Pontiac, same with 400 inch engines, chevy much smaller than a Pontiac as it was manufactured.
Another GM design that also has problems with having enough cooling system capacity is the Detroit Diesel 6.5 engine. Blown head gaskets in the early engines because of overheat issues. GM redesigned the whole cooling system because of warranty claims.
HO water pump to pump 40% more capacity, water crossover with 2 thermostats for the increased water pump flow, and a super duty thermostatic clutch to engage at lower temps, and reduce slippage, and a 7 blade fan. Those 3 items cut the warranty claims a huge amount.
Comparing same cubic inches for cooling system heat rejection from different manufactures, is always apples and oranges.
My Grand Prix in my signature pics has 2, 3 core radiators back to back. for a total of 6 cores to keep it cool. Fortunately that car had no cooling issues. The car that stumbled was not my own car, it belonged to a friend of mine, so I never worked on it the cure the gas starvation issues, he just didn't want to drive it that night, and I drove it for him. Was leading the feature when the caution came out, and lost the lead on the restart, almost got back by him, but ran out of laps.......
It wasn't the first time I had fuel starvation with Pontiac from fuel overheating on a dirt track, well versed on what happens when you sit on the track idling under caution and the underhood temps creep up.
Anyway, I have no idea of how he had the fuel system setup, as I never drove the car previously. I do know he also had a dual radiator setup copied from my Grand Prix. Routing the lines away from heat sources helps tons on a dirt track. If he had the stock line, they go right next to the thermostat housing, not good.
Oval track racing is totally different that drag racing, street driving, or autocross. 20 laps wide open builds a lot of heat in everything under the hood, so making everything as heat resistant as possible is the way you finish races. Everyone has their own ideas on how to get there. Lots of trial and error on my cars to get the ultimate fuel, and coolant setups.
Vapor lock, or fuel boiling?.
I lost because of it.