A close-up of a Victory exhaust valve spring and titanium retainer made for the DSR team. The dual valve springs have a 475-lb seat pressure, and the 300-degree cam has 0.500-in (12.7-mm) of lift.
In order to accommodate the variety of pistons, the Matco team keeps several head gaskets in stock, ranging from 0.040-in thickness to 0.120-in. This ain't all of them, either.
No one said torquing each stud to 185 ft-lb would be easy. Between the radiating heat from the block after a run and the occasional direct sunlight, rebuilding a nitro engine can appear to be a 40-minute sweat shop, and they sometimes do this up to four times over the course of about six hours.
DSR fabricates its own headers, which cost around $3000 a pop. Each cylinder has its own 2.75-in chromoly 4130 tubing exit (sorry, no cats), which you can fit a tennis ball inside of. The headers can last up to 50 runs, before the welds inevitably start to see cracking from the explosive heat. It sounds like a lot, but keep in mind that's still only 3 minutes and 30 seconds of wide-open throttle.
Fact #3: Nitro headers are pointed slightly upward to help with downforce but also slightly rearward to aid in forward propulsion. “If these headers were pointed straight down they'd literally start to lift the car off the ground,” says Brad Mason. He adds, “Sometimes you'll see it when a Funny car blows a header tube—it will literally blow the car slightly off the ground.”
Mason monitors fuel mixtures in each cylinder through the exhaust gas temperature, and he wants equal EGT's throughout. “If one is 200-300F cooler, something is wrong there, whether it's a valve not right or the car dropped a cylinder down the track. We want to be able to go look at when the cylinder dropped to discover why it dropped it. Without this data we can't tell where the cylinders are dropping mid run. So, it's a good diagnostic tool for us,” says Mason.