The SRP Professional Series pistons come with Teflon-coated skirts to reduce friction and
After figuring out how they wanted their valve job, they moved on to the actual runner design. They wanted a minimum cross-sectional area (MCSA) that would at least be physically capable of moving enough air so the engine wouldn’t starve at the peak rpm range of 6,500 rpm. But they wanted to be sure it was small enough that it would create a ton of velocity, which would aid in cylinder filling. An MCSA number of 2.06 square inches was picked and the boys went to town adding some epoxy in areas that, according to a velocity probe on the flow bench, showed little air movement. Dead areas. At the same time, they focused on grinding areas that showed excessive velocity, bordering on turbulent. Typically that means that good target air speed is around 300-350 feet per second. Below 275 fps is considered lazy, and over 400 means the air is on the verge of shearing or choking the port. Mapping out the port while porting and flow testing, they came up with an incredibly efficient design that gets the job done better than the vast majority of heads available. “I tried to widen the radii to make the port more efficient. I tried to make the port as straight as I could make it, and as even a speed as I could. On a 23-degree head, that’s about impossible.” Randy did a good enough port job that the heads ended up flowing about 290 cfm at .650-inch lift through a final runner volume of 204cc. Not half bad.
The forged side reliefs are easy to spot here as they cut out a ton of weight from a tradi
With the heads and bottom end built, the guys spent some time on the dyno trying a few different camshafts to see what would perform best. For some reason, regardless of the duration or lobe separation of the cam, the engine always made the best average power when it was set up to close the intake valve at 42 degrees after BDC using the .050-inch tappet lift reference. That appeared to be the point where the gains from holding the valve open to let more air in coincided with the gains from closing the valve and starting to compress the air fuel mixture. Randy said that regardless of the duration or lobe separation of the cams he tried: “We found more score with cam position rather than the actual cam changes.”
Offset intake lifters allow maximum widening of the intake runner at the pushrod pinch wit
With the engine now complete, Rick and Randy packed up with their crew and headed to the University of Northwestern Ohio in Lima to see how their bucks-down engine would fare against the high-dollar competition. After student volunteers bolted their mill to the DTS dyno, they ran a fresh batch of VP fuel through the Braswell carburetor and fired the engine to life. It purred like a kitten at idle but howled like a lion under full load through the Flowmaster mufflers. The dyno sheets spit out the facts that this little cast-iron pump-gas–friendly street engine made an incredible 606 hp. The brothers proved that not only could such a powerhouse be built on the cheap with a bit of thought and preparation, it could be replicated by almost anyone and outperform some of the best bucks-up crate engines on the market.
“Their plan was deceptively simple. Build a basic 383 combo using off-the-shelf components…”
The 50-Degree Valve Job
In the Apr. ’12 PHR, we brought some basic valve job tech issues to light. Thanks in part to the information given by Rick and Randy Ferbert, we were able to expand on the effects of using a steeper-than-normal valve job angle. When the valve begins to open, say .050 inch for example, there is a certain amount of area that is opened up between the seat and the valve. This is called the curtain area. In general, the curtain area is described as the circumference of the valve multiplied by the lift:
Ac = ∏ × Valve Diameter × Lift