Butler Built Pontiac Round Port 72cc Ram Air Aluminum Complete Cylinder Heads, Set/2

Cylinder Head Style: Machined and Assembled by Butler
Cylinder Head Material: Aluminum
Cylinder Head Finish: Natural
Combustion Chamber Volume (cc): 72 cc
CNC-Machined Combustion Chamber: Yes
Intake Runner Volume (cc): 215 cc
Exhaust Runner Volume (cc): 175 cc
CNC-Machined Intake Runner: No
CNC-Machined Exhaust Runner: No
Intake Port Shape: Ram Air IV
Intake Port Location: Standard
Exhaust Port Shape: Ram Air IV
Exhaust Port Location: Standard
Spark Plug Style: Straight
Comp. Valve Job: Yes by Butler
Intake Valves Included: Yes
Intake Valve Diameter (in): Ferrea 2.110 in.
Exhaust Valves Included: Yes
Exhaust Valve Diameter (in): Ferrea 1.660 in
.
Valve Springs Included: Yes Comp Cams/Lunati/Crower Depending on Cam
Hyd Roller or Hyd Flat Tappet (solid roller available at additional cost)

Maximum Valve Lift (in): 0.580 in.
Outside Diameter of Outer Spring (in): 1.450 in.
Damper Spring Included: Yes
Number of Springs Per Valve: Dual
Retainers Included: Yes
Retainer Material: Comp Chromeoly steel
Locks Included: Yes
Lock Style: Comp 10 degree
Valve Stem Seals Included: Yes
Valve Stem Seal Style: Positive stop
Rocker Arm Studs Included: No
Rocker Arms Included: No
Rocker Arm Nuts Included: No
Guideplates Included: No
Valve Cover Mounting Style: Center & Perimeter Bolt
Accessory Bolt Holes Drilled: Yes
Intake Valve Angle: 14 deg.
Exhaust Valve Angle: 14 deg.
Valve Guides Included: Yes
Valve Guide Material: Bronze
Valve Seats Machined: Yes
Valve Seat Machine Style: 3-angle
Valve Seat Material: Ductile iron
Steam Holes Drilled: No
Oiling Style: Through pushrod
Machined for O-Ring: No
Heat Crossover: No
Quantity: Sold as a pair.
Calculator Compression Calculator

Speedmaster Pontiac heads include valve sizes at 2.11" Intake, and 1.66" While the 2.11" valves are standard issue, the valve seat can be machined to accept a larger valve with minimal work.
Speedmaster CNC ported cylinder heads are machined on dedicated 4-axis and 5-axis CNC machining centers to ensure accuracy and cost effectiveness.

On the CNC ported versions, combustion chamber, Exhaust and Intake Ports all fully CNC machined for better flow. CNC combustion chambers offer superior control over flame travel and quench area. CNC Ported heads eliminate human error and variation from port to port. Unsurpassed repeatability from one cylinder head to another that is commonly found in "Hand porting & Polishing"

Combustion chambers are exact in volume - so every cylinder has the same compression ratio. Each port is the same cross section - so every cylinder can reach higher true RPM potential. CNC machining produces ports and chambers to within tolerances of no more than .002"; in turn every cylinder can reach the same power potential and accurate tuning.


INTAKE GASKETS
Our heads are manufactured with the Ram Air IV pattern which requires Felpro #1233 gaskets.

PUSH RODS
Please measure for exact pushrod length once heads and rockers are fully installed. Deck machining, head gasket thickness and rocker arm style will all affect pushrod height.

SPARK PLUGS
All Speedmaster Pontiac heads use standard 14mm. x 750" reach, 5/8 hex, gasket seat sparkplugs like NGK R5671A-7, Autolite 3924, Champion RC12YC, etc. Remember that higher compression/ boost require a colder heat range sparkplug.

HEAD BOLTS / STUDS
Our Pontiac heads utilize standard Ram Air Iv head bolts or studs.The ARP head bolt part number is 190-3605.