Product Summary

305, 327, 350, 400, Assembled Cylinder Head Style

  • Blemished
  • This product shows signs of installation or other finish damage, but does not affect use or fitment
  • This head is engraved with IMCA logo and serial numbered to make it approved for use in IMCA classes that allow the CH350I cylinder head
  • High-velocity 165cc/65cc intake/exhaust runners deliver strong mid-range torque
  • Assembled versions include 1.94"/1.50" standard length stainless steel valves, performance valve springs, retainers, keepers and 3/8" screw-in studs
  • SM version (Sport Mod) also has upgraded Comp Cams valve springs and lightweight Ferrea tool steel retainers
  • SC version (Stock Car) also has upgraded Comp Cams valve springs, lightweight Ferrea tool steel retainers, .080" milled deck w/ corrected intake for max compression

Key Specs

Garage Sale TypeBlemished
Cylinder Head StyleAssembled
Material TypeCast Iron
Combustion Chamber Volume64cc

Need To Know

This Product Will Ship Free

Shipping Policies & FAQs

Ineligible for Return

Contains items that cannot be returned


Garage Sale Product

This is garage sale priced because it was partially installed.

No Warranty, No Returns on Garage Sale Items    


IMCA Approved Stock Replacement Cylinder Heads

These Dart IMCA Approved cast iron Small Block Chevy cylinder heads are approved stock replacement heads for Hobby Stock, Northern & Southern Sport Mod, and Stock Car classes (using the 500 carbuertor). We begin with a Dart 10024360 Iron Eagle S/S 165 casting. Each head is engraved and serial-numbered to conform to IMCA rules.

After extensive research and development regarding the airflow capabilities and performance characteristics of this cylinder head versus previous models, IMCA approved this Speedway Motors-exclusive cylinder head and it's available for fast shipment in bare or assembled configurations.

Featuring precision cast ports and chambers, they have outstanding air flow. Assembled versions have optimized valve sizes for maximum performance within IMCA rules. 

(BARE) - Bare cylinder head

(HS) - IMCA Hobby Stock Heads

(SM) - IMCA Sport Mod Heads (Northern and Southern SportMod)

(SC) - IMCA Stock Car Heads 

Complete assembled versions include high-performance springs, 1.94"/1.50" standard length stainless steel valves, 7 degree locks and steel retainers with 3-angle valve jobs. 

  • Sport Mod and Stock Car versions includes high-performance COMP Cams valve springs and handle 0.550" net valve lift, with Ferrea tool steel retainers
  • Stock Car versions are .080" max flat milled w/ intake surface corrected to max out the compression rule for the IMCA Stock Car
  • Hobby Stock heads feature Speedway Motors USA-made high performance valve springs 180671515


  • Approved for IMCA Hobby Stock, Sport Mod and Stock Car classes (using 500 carb) as of 4/27/2020.
  • Assembled heads take approximately 1-2 days for assembly and will be shipped out promptly afterward. 


Material: Cast Iron

Comb Chambers: 64cc (SC) 76cc (SM/HS/BARE)

Intake Valve Dia: 1.940"

Intake Port volume: 165cc

Intake Port Dim: 1.100" W x 1.925" H

Int Port Location: Stock

Intake Gasket: Fel-Pro# 1204 or OEM type

Exh Valve Dia.: 1.500"

Exh Port volume: 65cc

Exhaust Port Dim: 1.340" W x 1.300" H

Exh Port Location: Stock location & bolt pattern

Exhaust Gasket: Fel-Pro# 1404

Flow, Intake: 210 cfm @ .500" lift / 28"

Flow, Exhaust: 138 cfm @ .500" lift / 28"

Head bolts: Stock bolts can be used

Milling: Min. 62cc = .060" (.0065" = 1cc) Flat Mill

Pistons: Most 23° aftermarket pistons.

Push Rod length: Stock (Stock length = 7.800") * Must measure *

Push Rod Guide: Stock type, integral

Retainers: Steel 1.250" = (7° )

Rocker Arm stud: Use screw-in stud w/integral nut

Spark Plug: Straight, .460" reach, tapered seat

Spring Cups: N/A, Use hardened shim or locator

Spring Pockets: Cut for 1.250" OD (.030" deeper max)

Valve Angles: 23°

Valve Length: STD = 4.890"

Valve Stem Dia: .3415" - 11/32"

Valve Guides: Integral cast into head

Valve Guide clearance: .002" - .0025" (with .3415 dia. valve stem)

Valve Guide Spacing: 1.890" moved .030" from stock

Valve Seals: Cut for umbrella seals

Valve Seats: Exh = Powdered Metal, .006" press

Valve Seat dim: Exh - 1.650" x 1.280" x .350"

Valve Seat angles:

  • Int = 32° - 45° - 60° - 70°- 80°
  • Exh = 37° - 45° - radius

Torque Specs:

  • Head Bolts = 70 ft/lb (w/ oil)
  • Rocker Studs = 55 ft/lb
  • Manifold = 35 ft/lb

Block Use: Any SBC, Iron or Aluminum


Weight: 52 lbs Bare – 58 lbs Assembled


MFG. Part #91624360-SC
BrandSpeedway Motors
Garage Sale TypeBlemished
Cylinder Head StyleAssembled
Material TypeCast Iron
Combustion Chamber Volume64cc
Intake Runner Volume165cc
Exhaust Runner Volume65cc
Intake Runner Volume Range160cc - 169cc
Exhaust Runner Volume Range60cc - 69cc
Spark Plug StyleStraight
Intake Port ShapeRectangle
Intake Port LocationStandard
Exhaust Port ShapeSquare
Exhaust Port LocationStandard
Intake Valve Diameter1.940"
Intake Valves IncludedYes
Intake Valve Angle23 °
Exhaust Valve Diameter1.500"
Exhaust Valves IncludedYes
Spring Diameter1.250"
Damper Spring IncludedYes
Valve Seat Machine Style3-angle
Valve Seats MachinedYes
Valve Seat MaterialPowdered Metal
Valve Guide MaterialIntegral, cast into head
Locks IncludedYes
Lock Style7 Degree
Retainers IncludedYes
Retainer MaterialSteel
Stud Diameter0.380"
Oiling StyleThrough Pushrod
Sold in QuantityEach