“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.
- 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.