World Products 042650-1 – Cylinder Head Cast Iron Chevy Small Block S/R 170cc 58cc 23Degree 1.940″ x 1.500″ (305CID) Straight Plug, Assembly w/ 1.250″ springs for hydraulic flat tappet lifters

World Products 042650-1 – Cylinder Head Cast Iron Chevy Small Block S/R 170cc 58cc 23Degree 1.940″ x 1.500″ (305CID) Straight Plug, Assembly w/ 1.250″ springs for hydraulic flat tappet lifters

World’s S/R cylinder Head are the preferred alternative to expensive OEM castings or junkyard rebuilds. These Head are designed with extra-thick decks and walls for improved reliability as well as equipped with hardened steel exhaust seats that are compatible with today’s unleaded gasolines. Needless to say, the S/R is substantially more durable than OEM castings.Valve cover rails have been raised and carefully machined to eliminate oil leaks and the Head can accommodate either early style perimeter or late model center bolt valve covers.S/R Cylinder Head  are fully 50-state emissions legal and because they are an OEM replacement head, they are legal for use by many oval tracks and race Sanctioning organizations…

TECHNICAL SPECS

• Casting ID Number: I-052, I-058
• Material: High density cast iron
• Valve Seats: Intake (integral), exhaust (hardened)
• Valve Guides: Integral cast iron
• Spring Seats: Machined for 1.560″
• Valves: ERSON stainless steel valves in assemblies
• Valve Diameter: 1.940″ intake, 1.500″ exhaust   (11/32″ stem)
• Rocker Arms: 1.5 ratio (1.6 ratio may require elongation of pushrod holes)
• Intake Runner: 170cc, standard port location
• Exhaust Ports: 65cc
• Combustion Chamber: 58cc
• Spark Plug: 14mm 5/8″.460″ reach tapered style. EX. ACCEL 276 or 276S
• Valve Job: Multi-angle intake and radius exhaust
• Valve Cover Rail: Raised w/ perimeter
• Valve Angle: Stock 23°
• Accessory Bolt Holes: Stock
• Guide Plates: Not machined for them
• Rocker Arm Studs: Not Included
• Springs: 1.250″ Max Lift .560″

World Products S/R 170cc Iron Head Flow Data 
Valve Lift–.300 –.400 –.500 –.600 –.700 –.800 

1.940 —-   182 — 216 — 232 — 225  –217 — 217
1.500 —-   125 — 147 — 161 — 168 — 169 — 169   

Methods used: Superflow 600, Flowed at 28″ with a bowl blend 1″ down, 1″ radiused entry plate on the intake port, No exhaust tube, Using Manley Race Master valves.

Heads are sold individually.