*PAIR* Chevy 350 CNC Cylinder heads, 225 runners, 64cc Alloy *STRAIGHT* Plug, BARE - Small Block Chevy, SBC

DRP CNC Ported Chevy 350 Cylinder Heads — Straight Plug, Bare Pair

Quick fitment summary: DRP-SBC225CNC-S is a bare pair of CNC ported aluminium cylinder heads for Small Block Chevy 350 / SBC engines. They use a 23° valve angle, straight spark plug location, 64cc as-cast chambers and CNC ported 228cc intake runners. Sold bare for engine builders who want to choose their own valves, springs and hardware. See our other listings for assembled options or contact us. 

Pair of Detroit Racing Products CNC ported Small Block Chevy cylinder heads. Straight spark plug location, 23° valve angle, sold bare (no valves, springs or retainers).

DRP heads are built for engine builders who want serious port and chamber performance without paying boutique prices. Fully machined and ready to assemble out of the box.

Why straight plug?

Straight plug heads suit the majority of stock and traditional Chev 350 builds — a direct fit where the original block, headers and accessories are designed around the factory plug location. If you're running a tight engine bay, conventional headers, or replacing factory iron heads, straight plug is the right call.

Why we don't CNC the chamber

DRP heads are cast using permanent mold casting — the same process used for OEM-quality production castings. We've inspected the foundry firsthand and verify quality control on every annual visit. The chamber comes out of the mold to a finish that doesn't need CNC work. CNC machining the chamber would enlarge chamber volume and drop compression. Ours stays at 64cc as cast, and can be milled to 60cc to push compression further.

Milling note: .006" per CC - can be machined to a minium of 60cc

DRP Chevy 350 CNC ported Straight Plug Cylinder heads Specifications

• Spark plug location: Straight
• Valve angle: 23°
• Intake runner: 228cc (CNC ported) (classified as 225cc)
• Exhaust runner: 88cc (CNC ported)
• Combustion chamber: 64cc as cast (millable to 60cc; ~1cc per 0.006")
• Intake valve seat: 2.020" (can be cut to 2.080") 3 Angle Race CNC Finished 
• Exhaust valve seat: 1.600" 3 Angle Race CNC Finished
• Valve job: 3-angle
• Valve guides: Premium bronze, 0.570" OD
• Valve guide seal size: 0.530" x 11/32"
• Material: Hard 355-T6 aluminium 
• Casting Quality: Permanent mold cast, OEM-level high quality, thick decks, smooth water jackets

Recommended parts (sold separately)

• Intake valves: Ferrea F5027-8 — 2.020" x 5.011" long x 11/32" stem
• Exhaust valves: Ferrea F5025-8 — 1.600" x 5.011" long x 11/32" stem
• Valve stem seals (Viton): COMP 518-16
• Valve stem seals (Teflon): COMP 503-16
• Guide plates: COMP Cams 4835-8 or DRP-4835-GP
• Intake gaskets: Felpro 1205 (standard port) or Felpro 1206 (ported)
• Spark plugs: NGK BCPR7ES — 750 reach, gasketed, 5/8" hex

Supplying Chevy 350 parts since 1979. Our sales team of actual engine builders are on hand to help. Call 1800 351 351 or message us on this page — we'll get you the right parts first time.

We hold a large range of DRP cylinder heads in our Melbourne warehouse and ship Australia-wide. We stock our own lines — no drop-shipping, no waiting on overseas suppliers. Check our google reviews for what our customers say about pricing and dispatch speed.