Technical Specifications of...
Motown 23° Cylinder Heads

Material: 355-T6 Aluminum

Combustion Chamber : All, 64 cc
Valve Guides: Bronze
Valve Spring Seats: Machined for 1.550" spring locators
Valve Size: 215cc Head - 2.080" x 1.600" / 235cc Head - 2.080" x 1.600"
Rocker Arm Studs: Screw-in style with hex ( 7/16" all models) shoulder furnished with assembly
Accessory Flange: Stock bolt hole locations.
Included In Assembly: Manley stainless steel valves with swirl-polished heads, umbrella ( -1 &-2 models) or PC (-3 models) style seals, 1.250" (-1 models) 1.437" (-2 models) or 1.550" (-3 models) Hardcore valve springs, Manley 7° (-1 & -2 models) or 10° (-3 models) chrome moly retainers and keepers.
Recommended Installation Items:
Head Gaskets: Fel-Pro #1003 or equivalent
Pushrods: Requires heat-treated pushrods. Use of 1.6 ratio rocker arms requires elongation of pushrod holes.
Spark Plugs: Accepts 14mm 3/4 " reach tapered seat (Accel 416 or equivalent)
Intake Gasket: Mr. Gasket 5821 or equivalent
Exhaust Gasket: Fel-Pro #1404 or equivalent
Machine Shop Specifications:
Maximum Valve Diameter: 215cc head: 2.080" x 1.600" or 235cc head: 2.080" x 1.600"
Maximum Spring Seat Depth (from inside step): .030"
Maximum Spring Diameter: 1.550"
Approximate Milling Guideline (varies with depth): .007" per cc
Maximum Flat Mill Depth (up to intake seats): .080"
Maximum Angle Mill (approx. 50-52cc volume): .175" depth
Note: These specifications are for reference only. ALWAYS measure before machining.