Building A 506HP Street 462 From A 400

RPM Torque HP
3,400 582.8 377.3
3,600 587.1 402.4
3,800 590.4 427.2
4,000 592.5 451.2
4,200 590.0 471.8
4,400 582.1 487.7
4,600 570.9 500.0
4,800 554.2 506.5
5,000 531.9 506.4
5,200 508.1 506.7
5,400 479.9 493.4

Joe related, “though the carb spacer normally does lean the mixture slightly, the out-of-the-box jetting was nearly perfect for this combo.”

Engine Buildup Worksheet
Displacement 400/462
Bore/Stroke 4.181×4.210-in
Block/Crank Combo ’67 400/4.210 stroker
Bore/Stroke Ratio 0.993:1
Rod/Stroke Ratio 1.574:1
Bottom End
Block ’67 GTO 400, code WT
Preparation Bored and honed 0.060-over
Deck Height 10.250-in
Crankshaft Joe Sherman Racing cast 455 stroker
Preparation Balanced
Balancer Aftermarket replacement, degreed
Rods Cast, 6.625-in
Preparation Size the big and little ends, install new rod bolts, balanced
Bearings King
Pistons KB Hypereutectic, 0.030-455 flat-top with valve reliefs
Piston to Deck Height 0.005-inch
Piston Pins KB press-fit
Piston Rings Hastings moly top, cast-iron second
Head Bolts ARP
Balancing Spec 2,210g bob weight
Oiling System
Oil Pan Replacement with baffle
Oil Pump Mellings
Brand Edelbrock aluminum, 60579, closed chamber
Modifications As delivered from Edelbrock
Combustion Chamber Volume 87cc
Maximum Flow at 28 Inches of Pressure:
Intake 275-cfm at 0.700
Exhaust 185-cfm at 0.700
Compression Ratio 10.0:1
Valves Edelbrock 2.110/1.660-in
Angles Used in Valve Job 30-, 45-, 60-deg
Mods None
Retainers Chromoly
Keepers Steel 7-deg
Valve Guides Edelbrock bronze
Rocker Studs ARP 7/16-in
Roller Rocker Arms PRW full roller, 1.52:1
Pushrod Diameter 5/16-in
Brand Comp Cams hydraulic roller
Grind XFI 280HR
Duration at 0.050 230/236-deg
Lift 0.540/0.543-in
Centerline 108-deg
Lobe Separation Angle 110-deg
Installed Position 108-deg
Lifters Comp Cams hydraulic roller
Valve Springs Comp Cams dual
Seat Pressure 145 lbs
Open Pressure 395 lbs
Timing Chain Comp Cams dual-roller
Intake Manifold Performer RPM
Mods Plenum clean-up
Carb Edelbrock No. 1412, 800-cfm
Mods None
Jets/Primary 0.113
Jets/Secondary 0.101
Primary Metering Rod Size 0.071-0.047
Fuel Line 3/8-in diameter/No. 6 AN
Distributor Stock-type, Pertronix conversion
Coil MSD
Wires ACCEL 7mm solid core
Total Timing 40-deg
Initial Advance 16-deg
Mechanical Advance 24-deg
Vacuum Advance None
Brand Mad Dog Exhaust Products custom
Primary Tube Diameter 1.875-in
Primary Tube Length 30-in
Collector Size 3 1/2×7-in
Brand Edelbrock


Joe Sherman Racing Engine’s Cast Crank Features The 4.210 Inch Stroke Of A 455 And The 3.00 Inch Mains To Fit The 400 Block. Installing A 455 Spec Crank In A 3.00 Inch Main Block Sometimes Requires Mild Clearancing At The Front Of The Block Where The Front Counterweight Will Travel.

For The Record, Every Block Spec And Dimension Was Checked Out, Noted, And Blueprinted For The ’67 WT Code Block. To Accept 0.030 455 Pistons, The Cylinders Were Bored 0.060 Inch.

Stock 6.625 Inch Connecting Rods Were Press Fit Onto Keith Black (KB) Hypereutectic Pistons. This Type Has The Increased Strength Of A Forged Piston With The Lesser Expansion Rate Of A Cast One. Less Piston To Cylinder Wall Clearance Means Better Ring Seal.

Here’s The Short Block Buttoned Up Just Prior To Fitting The Oil Pump. By Retaining The Two Bolt Mains And Stock Caps And Employing A Cast 4.210 Stroke Crank, Cast Rods, And Hyper Eutectic Pistons, The Budget Is Kept In Check, While Power For The Street Is Generated. For Added Bottom End Insurance Or Higher Rpm Potential, Forged Connecting Rods Can Be Used For Your Buildup.

Money Was Well Spent On The Benefits Of A Hydraulic Roller Camshaft From Comp Cams. The Design Of The Roller Cam Lobes Lets The Valves Reach Maximum Lift More Quickly Per Degree Of Duration Than Flat Tappet Cam Lobes, Which Aid Cylinder Filling And Evacuation, Thus Increasing Power Output. Less Overlap Required In A Hydraulic Roller As Compared To A Hydraulic Flat Tappet To Get This Increased Power Can Result In A Smoother Idle And Improved Low Speed Performance. There’s Also A Reduction In Friction Thanks To The Roller Lifters.

Roller Cams Generally Don’t Need Any Initial Start Up Lube, But Joe Sherman Lubes The Lobes And Lifters Anyway.

Edelbrock’s No. 60579 Aluminum Heads Feature 87cc Combustion Chambers And Can Be Ordered Either Bare Or Complete With Valves, Springs, And Guide Plates. Sherman Chose The Latter.

The Oil Pan Is A Joe Sherman Racing Stock Type Replacement. This One Is A Later Model That Features A Baffle In The Bottom To Keep Oil At The Pickup During High G Driving. That Shouldn’t Really Be A Problem With The ’61 Cat, However.

This 4.181×4.210 “undersquare” Engine Makes Big Torque And Horsepower Between 3,400 And 5,400 (max) Rpm. At Max Valve Lift, The Heads Flow 275 Cfm Intake And 185 Cfm Exhaust Out Of The Box, Which Negates The Need To Port Them For This Combination.

Shown Here Is An Edelbrock Bronze Wall Valve Guide, A Smooth As Cast Pocket Area, And Hardened Valveseat Inserts For Unleaded Gas.

The 87cc Combustion Chambers Will Provide 10:1 Compression When Combined With The 4.181 Bore, The Flat Top Piston’s Compression Height And Valve Reliefs, 0.005 Piston To Deck Height, And The Volume Of The Head Gasket. A Set Of 2.11/1.66 Inch Stainless Valves Is Included When The Assembled Head Is Purchased.

“D” Shaped Exhaust Ports Were Proven Decades Ago On GM Tech Center Dynos To Work Best On High Performance Engines. Though The Heads Are Based On The Round Port R/A IVs, The Exhaust Port Design Was Changed In The Edelbrock Head To This D Shape. Nevertheless, The Round Port Manifold Or Header Configuration Is Required When Using These Heads.

You Can See The 7/16 Inch Screw In Rocker Arm Studs And Included Pushrod Guideplates As The Head Bolts Are Torqued In Sequence.

Valvesprings And Retainers Are Comp Cams Issued. PRW Full Roller, Forged Aluminum Rocker Arms Are Plainly Stamped With The Engine Size, Stud Diameter, And Rocker Arm Ratio. Valvetrain Geometry Must Be Fully Checked On Every Engine With Aftermarket Heads, Especially Aluminum, Because Spring Pads And Valve Placement Can Be Slightly Different Compared To Stock, So Proper Roller Rocker Arm Tip On Valve Stem Positioning Must Be Verified.

Since Pontiac Never Used Round Port Heads In A ’61 Model, Middleton Had Custom Headers Built To Run The Edelbrock Heads In His Catalina. Mark Delcamp, Proprietor Of Mad Dog Exhaust Products In Allen, Michigan, Makes The Company’s Headers One Set At A Time. He’s Been At It Since 1989 And Before That Was A Honcho At The Legendary JR Headers In Detroit. These Early Pontiac Headers Feature Heavy Duty 16 Gauge (0.065 Inch Wall) Tubing.

A Pertronix Electronic Ignition Conversion Is Hiding Under The Distributor Cap. ACCEL Wires Deliver The Spark To NGK FR 5 Plugs.

Sherman Adds A 1 Inch Spacer To The Performer RPM Intake Manifold, Which He Says Is Worth An Additional 10 Hp. As Well As Providing WOT Power, Since The 800 Cfm AFB Carburetor Features Primary Metering Rods That Work Off Engine Vacuum, They Can Meter Fuel 12 Percent Leaner Or Richer, Benefiting Performance Or Economy Depending On How The Engine Is Being Used. Hood Clearance With The RPM Intake And Spacer Might Be Questionable On Some Pontiacs, But Not Orwin Middleton’s ’61 Catalina.

Sherman Had The New Harmonic Balancer “degreed” From 10 Degrees After Top Dead Center (TDC) To 50 Degrees Before. After Degreeing In The Camshaft, He Had To Make A New Timing Pointer. He Also Marked In White: TDC, The Pointer Tip, Plus 30 And 40 Degrees Before TDC. Exact Engine Timing Is A MUST! It Should Also Be Noted That The 455 Had The Benefit Of Being Dyno Tested With No Pulleys Or Drive Belts, Per Se. This Can Save 6 7 Hp.