03/07/2026
This OBS Chevy showed up mostly in pieces — basically a long block with buckets of parts in the bed and cab. After a lot of fabrication, wiring, troubleshooting, and tuning, it’s now a fully sorted Holley Sniper EFI truck that drives better than factory.
I took on this job initially as kind of a favor for a friend, with the understanding that it would be something I worked on when I had time. I severely underestimated the scope of the project, but man it turned out slick.
The truck arrived mostly disassembled with the camshaft, valve springs, and intake already installed. It had a mild Summit 8800 camshaft (204/214 @ .050, .450 lift), upgraded valve springs, and a Weiand Street Warrior intake.
The customer had purchased a full Holley Sniper EFI system — throttle body, Hyperspark distributor, coil, transmission controller, etc. I started off installing the distributor and recommended a set of 1.5:1 self-aligning billet aluminum roller rockers. While going through everything I found some issues related to the timing cover from the cam install, so I put the truck on the lift, corrected that, and installed a new oil pan gasket.
While it was on the lift I also installed the new manifold-to-muffler fl**ge exhaust that came with the kit and began running wiring for the transmission controller. The transmission had recently been rebuilt, and when I went to plug the pass-through connector in the transmission side connector popped into the pan. After pulling the pan I found the connector had been siliconed in because the plastic retaining clips were broken. I sourced another harness, pulled the valve body components, and corrected the issue.
From there I removed most of the components from the firewall and fender so I could properly mount all of the Holley controllers. Everything was laid out, holes drilled, and riv-nuts installed so everything bolted in cleanly. We removed all of the unused circuits from the factory harness and integrated the Holley wiring so it looks like a clean OEM-style harness.
The Sniper system requires 55–60 psi of fuel pressure, which the factory pump conveniently provides. I used push-lock to AN adapters to utilize the factory steel fuel lines and built AN hoses to plumb the throttle body. Because the Sniper requires a regulated return system, I fabricated a bracket and installed an Aeromotive fuel pressure regulator with a liquid-filled gauge to dampen pressure pulses.
The customer wanted all factory functions retained, including the A/C. Taller valve covers are required to clear the roller rockers, which caused clearance issues with the compressor. I ended up notching the accessory bracket and machining spacers on the lathe to raise the compressor and run a longer serpentine belt.
Several circuits in the factory harness had to be extended so everything would fit properly with the new components. The Holley system gets its RPM signal from the distributor, but the factory ECU still needs the signal from the crank sensor in the timing cover for certain functions. The factory tachometer also requires a separate signal, so I tied the Sniper tach output into the factory tach wire. The Holley also has a speedometer output, but using that disables factory systems like ABS and cruise control, so those circuits were retained and tied together at the vehicle speed sensor.
The throttle bracket ended up being a modified piece from an ’80s squarebody parts truck. I also used the throttle cable from the squarebody since the pedal connection and firewall pass-through are very similar. Because the Sniper throttle body is shaped like a carburetor, the squarebody cable worked perfectly.
I also ended up installing a new starter and building new cables after discovering the original cable had melted. Once that was corrected the engine fired right up.
For the intake I had Eric Bates cut some pieces on the plasma table so I could build a custom heat shield and airbox. I welded everything together, painted it black, and mounted the radiator overflow on the back side. Had to add a little Texas pride to it.
After getting everything running it was time to dial in the tuning. The Sniper system provides base parameters to get the engine running, but it still required a lot of dialing in. Timing sync, IAC setup, idle spark, and transmission shift scaling all needed adjustment to get everything working exactly the way it should.
After several rounds of testing and road tuning I finally have everything dialed in and it is an absolute blast to drive. The A/C is blowing 39 degrees, every factory function works exactly like it should, and the engine bay came out clean.
I’m extremely proud of how this one turned out after a lot of time and detail work. I have a couple small tweaks to finish over the weekend and it will be heading back to a very happy customer.
On to the next one.
