Project Street Reaper: Our SBC 350 Carburetor Setup
If you’ve been following Project Street Reaper, you know where we left off. Part 3 covered bolting AFR Enforcer as-cast cylinder heads onto our SBC 350. Now, Part 4 brings the full SBC 350 carburetor setup together. This is also the part where the car runs for the first time. We tackled the intake, carb, spacer, alternator, electric fans, and harmonic damper. On top of that, we broke in the flat tappet cam. A lot went down. Let’s get into it.
Edelbrock P/N 7501: The Intake Choice And Why
The intake manifold for this build is the Edelbrock Performer RPM Air-Gap, P/N 7501. It’s a dual-plane aluminum unit for 1955-86 small block Chevy V8s in the 262-400 cubic inch range. What separates the RPM Air-Gap from a standard Performer manifold is the open air space between the intake runners and the lifter valley cover. Edelbrock borrowed that design directly from their Victor Series competition lineup. As a result, the incoming air/fuel charge stays cooler and denser all the way to the cylinder heads.
The power band runs from 1,500 to 6,500 RPM. That sits 1,000 RPM higher than the original Performer Air-Gap. For a streetcar that needs to pull hard through the mid and upper range, that spread makes perfect sense. We always planned this build to be old school and scream. A leftover from a different project that went a different direction, the 7501 fit the goal perfectly. Since high-rise induction performance was already the target, spending money on a spacer instead of a whole new intake was the smarter move.
High Velocity Heads 2″ Super Sucker Carb Spacer
To stack on top of our SBC 350 carburetor setup, we added a 2″ aluminum Super Sucker carb spacer from High Velocity Heads, P/N SS4500-2-1AL. The Super Sucker runs a 2.125″ open bore and handles 4150-flange carburetors up to 1,250 CFM. More plenum volume slows charge velocity at idle and cruise. However, when the throttle opens wide, the taller stack creates a high-rise effect. As a result, the air/fuel mix builds speed before it reaches the carb, which complements the Air-Gap’s runner design perfectly.
One lesson learned: the Edelbrock 7501 sits tall. The 12″ oval air cleaner we originally ordered looked ridiculous on top of the spacer and manifold. So we sourced a 15″ oval kit instead. That swap solved the proportion problem immediately.
ATM Innovations 750 CFM XRSC
Here’s the highlight of this entire SBC 350 carburetor setup: the ATM Innovations XRSC Street Strip Series 750 CFM gas carburetor. ATM builds the XRSC on die-cast aluminum main bodies, metering blocks, and throttle bodies. Each unit includes fully tunable air bleeds and fuel channel restrictions. The carb runs a 4150 flange and carries vacuum ports for vacuum advance and PCV hookups. ATM also builds in their dual-inlet, dual-site-window aluminum fuel bowls. Overall, the XRSC series comes in five sizes from 650 to 1,050 CFM, all on a 4150 flange.
Now, the price point. Under $700 for an all-aluminum, USA-made carburetor is hard to believe. For that same money, competitors sell a shelf-stock piece. ATM, however, will custom-build a carb to your exact combination at that price. We didn’t custom-order our 750 CFM unit. Even so, it went on the engine and ran without a single adjustment beyond the idle speed screw. No chasing a bog, no needle and seat work, no leaning out the primaries. We bolted it down, and it was right.
In hindsight, a 650 CFM unit probably would have covered this 350 with the AFR Enforcer heads. Still, Part 5 brings upgrades that will justify the extra 100 CFM. So the 750 will earn its keep soon enough.
For the air cleaner, we found a 5″ tall K&N filter element that fits inside the 15″ oval lid. The standard 2″ filter that comes in most kits would have choked the combination. Instead, the taller K&N gives the carb proper surface area and keeps restriction out of the equation entirely.
Hardware, Alternator, Electric Fans, And Damper
For fasteners, all intake and carb hardware came from ARP. The intake bolts are from ARP P/N 534-9801. For the carburetor and spacer, we ran ARP P/N 200-2404 studs at 3.7″ tall. Those studs clear a 2″ spacer stack without any clearance issues. ARP hardware is the only answer when you need something to stay torqued permanently.
Next, we swapped the factory alternator for a PROFORM P/N 66445.12N. This is a 120-amp, 100% new chrome unit in GM 1-wire style with a machined pulley. The stock alternator doesn’t have the output for an electric fan setup. Our Amazon fan setup draws around 30 amps on its own. It’s a spare 1,700 CFM unit from my Nova build, and an upgrade is already on deck. For now, we wired it through a Ron Francis dual electric fan relay kit, P/N AR-77. The instructions in that kit are detailed and clear. We mounted the relays on the passenger side firewall, which kept wire routing short and clean.
For the harmonic damper, we ran a Summit Racing SBC balancer, P/N SUM-161358. A 6″ balancer would have been the preference. However, Summit didn’t have stock on those at the time. The 8″ unit works fine, and the horsepower difference at this stage is too small to matter. We torqued it down with an ARP SBC balancer bolt, P/N 134-2501.
First Fire And Cam Break-In
After we finished the final assembly, we lit the engine for the first time. Cam break-in on a flat tappet is not optional. Furthermore, you cannot rush it. First, we filled the engine with Lucas Oil SAE 30 break-in oil. That oil carries elevated zinc and phosphorus (ZDDP) content, which flat tappet lifters need during the initial wear-in period. Then we fired the engine and held it at 2,500-3,000 RPM for 20 minutes. We varied the speed slightly throughout, so fresh oil swept the lobes and lifters from different angles.
After that, we drained and checked the oil. The metal content came out exactly where it belongs on a fresh flat tappet grind. The Summit Racing cam and lifters are seated correctly. No drama, just clean confirmation that the full SBC 350 carburetor setup and induction stack put the engine exactly where it belonged on its first fire.
The ATM Innovation carburetor sat spot-on from the first crank. The idle settled in clean. Project Street Reaper sounds like an old school street motor that means business.
What’s Next
Part 5 is coming, and this time it includes video. Car Junkie Mag is stepping into video format, and you’ll be able to watch the next installment and hear the car run for yourself. Beyond that, more upgrades are on deck that will push this combination further. Stay tuned.
Parts referenced in this article:
- Edelbrock P/N 7501 – Performer RPM Air-Gap Intake Manifold
- High Velocity Heads P/N SS4500-2-1AL – 2″ Super Sucker Carb Spacer
- ATM Innovations XRSC 750 CFM Street Strip Gas Carburetor
- ARP P/N 534-9801 – Intake Bolt Kit
- ARP P/N 200-2404 – Carburetor Studs (3.7″)
- PROFORM P/N 66445.12N – 120-Amp Chrome Alternator
- Ron Francis P/N AR77 – Dual Electric Fan Relay Kit
- Summit Racing P/N SUM-161358 – SBC Harmonic Damper
- ARP P/N 134-2501 – Harmonic Balancer Bolt
- Lucas Oil SAE 30 Break-In Oil
