PRI 2019: World Products’ 305 SBC Cylinder Heads For Dirt Oval

“As far as I know, we are the only ones casting these 305 iron heads,” said World Products’ Marketing Director, Jack McInnis. “If you notice, these heads are designed for durability with extra-thick decks and walls, as well as hardened-steel exhaust seats for modern gasoline formulas.”

The 305ci Chevy was once a disrespected engine, often viewed as a weak-kneed economy engine. Dirt track racing has seen the once-maligned engine as a potent economic powerplant, much the way the two-speed Powerglide transmissions found favor with the dirt-oval racers.

“You’ll notice we’ve changed our valve-seat grinding techniques for sealing,” McInnis added. “Because these are 50-state legal and an OE replacement head, these are legal for most oval tracks.”

Features And Benefits:

  • Intake Runners: 170cc – port dimension: 1.940 inches x 1.170 inches
  • Exhaust Runners: 65cc – port dimension: 1.345 inches x 1.370 inches
  • Combustion Chamber Volume: 58cc. See the cylinder head part number list for chamber size.
  • Valve Guides: Integral cast iron guide
  • Valve Guide Spacing: Ctr-Ctr = 1.900 inches (Intake stock location/Exhaust is moved .040 inch)
  • Rocker Arms: These heads utilize a standard-offset rocker arm designed for the small block chevy.
  • Head Bolts: standard SBC head bolt hardware (ARP bolts134-3601)
  • Head Studs: standard SBC head Stud hardware (ARP studs 134-4001)

NOTE: When using rocker arms greater than a 1.5 ratio, it may be necessary to elongate the pushrod guide holes in the cylinder head. 

  • Head Gaskets: Fel Pro 7733PT or 1003. If steam holes are needed for 400 engines, use a 1014 gasket. These heads are not drilled for steam holes. If steam holes are desired, it is necessary to drill six 1/8 steam holes. 
  • Intake Manifold: accepts any conventional SBC intake manifolds
  • Pistons: Most 23-degree aftermarket pistons
  • Spark Plugs: .460-inch reach, 5/8-inch hex plug.

Part Numbers:

  • 042650 I-058 Bare head, 23-degree valve angle, 170cc intake runner, 58cc chamber, straight plug
  • 042650 – 1 Assembled head, Hydraulic Flat Tappet Camshaft
  • 042750 I-058 Bare head, 23-degree valve angle, 170cc intake runner, 58cc chamber, straight plug ( 1987 & Later Intake Face, Center Bolt Valve Covers )
  • 042750 – 1 Assembled head, Hydraulic Flat Tappet Camshaft

For more information on the 305 cylinder heads of other engine components from World Products, visit them online at www.pbm-erson.com.

Article Sources

About the author

Bobby Kimbrough

Bobby grew up in the heart of Illinois, becoming an avid dirt track race fan which has developed into a life long passion. Taking a break from the Midwest dirt tracks to fight evil doers in the world, he completed a full 21 year career in the Marine Corps.
Read My Articles

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