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ProMAXX Cylinder Heads_Chevrolet Big Block_Shocker CNC_370cc_2.300/1.880_121 cc
ProMAXX Cylinder Heads

Photo may not be actual product


Optional Cylinder Heads:

PMX-9170 Bare
PMX-9371 Hydraulic Roller
PMX-9372 Solid Roller
PMX-9372T Solid Roller w/Ti Retainers
PMX-9373 Solid Roller w/Ti Retainers

ProMAXX Shocker CNC Series is the top of the line performance cylinder head. It features professionally designed runners and chambers that are meticulously CNC ported. The all new ProMAXX ultra smooth Grade A 356-T6 aluminum casting is CNC machined to create the perfect platform for newly developed runner and chamber designs. This is combined with a 5 angle competition valve job, diamond honed bronze guides, large spring pockets and professional assembly, performed right here in the United States. Pro MAXX Shocker CNC Heads are proof that going fast doesn’t have to break the bank.

  • 370cc Intake runner
  • Ultra smooth 356-t6 Aluminum
  • .750 thick decks
  • Precision CNC Machining
  • Unshrouded chamber
  • Diamond honed guides
  • Large spring pockets
  • 5 angle valve job
  • Precision CNC machining
  • Multiple spring options

Assembled heads feature:
  • One piece stainless steel valves
  • 21-4N back cut, swirl polished
  • Multiple spring options
  • Designed, machined and assembled in the USA

Item# Item Name Price Qty Add
PMX-9370 Shocker CNC_Chevrolet BB_370cc_Bare
PMX-9371 Shocker CNC_Chevrolet BB_370cc_H/R_.600 Max Lift
PMX-9372 Shocker CNC_Chevrolet BB_370cc_S/R_.700 Max Lift
PMX-9372T Shocker CNC_Chevrolet BB_370cc_S/R_.700 Max Lift_w/Ti Retainers
PMX-9373 Shocker CNC_Chevrolet BB_370cc_S/R_.900 Max Lift_w/Ti Retainers
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Flow Chart:

Flow Data: cfm @ 28 inches of Water
Lift .200 .300 .400 .500 .600 .700 .800
.900 1.00
Intake 177
271 323 365 387 400 412 417 417
Exhaust 148 195 243 270 289 307 310 312 315

Technical Specs:
Item Code PMX-9370-000
Vendor ProMAXX Performance Products
Product Type Cylinder Heads
Product Model Shocker CNC Series
Engine Family Chevrolet Big Block
Material 356-t6 cast aluminum
Weight 86 lbs
Combustion Chamber 121 cc
Plug Orientation Angle
Intake Runner 240 cc
Exhaust Runner 135 cc
Intake Valve Diameter 2.300
Exhaust Valve Diameter 1.880
Valve Angles 24° intake 15° exhaust
Valve Seats Hardened Steel
Valve Guides Manganese Bronze
Valve Seals Viton
Standard Retainers Steel
Valve Job Type 5 Angle
Head Bolts ARP 135-3703 Mark IV/135-3707 Mark V
Valve Spacing OEM
Intake Gaskets Fel-Pro 1275 (may require slight trim)
Exhaust Gaskets Fel-Pro 1412
Head Gaskets Fel-Pro 1047 Mark V and Mark VI/1017 Mark IV
Spark Plug .750 Reach Gasket Seat
Torque Specifications 80 ft lbs in 3 increments using 30wt oil
Notes: Exhaust port is raised .375

Valve Spring Pressures

Hydraulic Roller - .600 Max Lift
Closed 135 lbs @ 2.000
Open 365 lbs @ 1.400

Solid Roller - .700 Max Lift
Closed 230 lbs @ 2.000
Open 600 lbs @ 1.300

Solid Roller - .900 Max Lift
Closed 332 lbs @ 2.100
Open 950 lbs @ 1.200

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Cylinder Heads > ProMAXX Cylinder Heads > Chevrolet _ Big Block