Ive got a stock h1c/18, fuel pin, 366, and 2/3 turn on the screw. Shifting @ 2800, a WOT run from 0-80 peaks at 1250. If I take it to 90 mph EGT can get to 1300-1325 depending on air temp. There are variables of course between your rig and mine.
Long story short, you could safely run WOT in your rig for 10-15 sec without worrying (before getting the pyro). I say 15 sec because that is a lot of peoples personally imposed timeframe when above 1250, and your still not running a ton of fuel. But without a pyro we still dont know.
Above 1250, it is ENTIRELY about time. For example: If I peaked @ 1300 degrees, I'd feel comfortable holding 1300 for 30 seconds or so. If you were pegging a 1600 deg. pyro, then no I wouldn't hold it there for 30 seconds
Just to clarify, ALL of the timeframes I posted are ballparks/estimates, and carry no real weight. It is unknown how long 1300, 1350, 1500, or even 1800 degrees can be sustained before junk starts sloughing off your pistons. And EGT damage is generally cumulative, meaning unless you actually meltdown, damage will occur over time bit by bit.
1992 W250, 5 speed, 4.10, Ext. cab Ext. bed, 12.5k winch, 75 gal. fuel tank
H1C/18
Fuel: Power Driven Stage 2 sticks, THD 12 psi piston pump, THD fuel pin, 366 spring, fuel screw 1 turn in, timing to the head/ >1/4”
Muffler delete