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1973 Pontiac LeMans

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Engine:

Block:

  • 1968 400 (290 HP) YC Auto 10.5CR Block Casting # 9790071 (production number 278569)
  • Bore: 4.12 (stock) + .040 overbore = 4.162
  • Stroke: 3.75 (stock)
  • 408 CID
  • Zero Deck Height

Heads:

  • 1968 #16 castings (H.O.)
  • Bowls blended
  • Intake ports ported and matched to intake manifold.
  • Intake flow rate is 280 cfm.
  • Exhaust ports were ported to flow 240cfm
  • Compression ratio (with head gasket installed) is 11.15
  • (Fel Pro gasket: thickness, 4.300 in. gasket bore, 9.4 cc compressed volume, .039 inch compressed thickness)


Valvetrain:

Camshaft: Comp Cams Solid Roller: Lobe lift is .400inch. Gross valve lift is .600 inch lift on both intake and exhaust. Duration @.050 lift is 265 degrees on int. 270 degrees on exh.
Lifters:

  • Comp Cams Solid Rollers
  • Comp Cam 917 Springs
  • I.D. .824
  • Seat Load 200@1.800
  • Open Load 596@1.100
  • coil bind 1.050
  • rate 566lbs\in
  • titanium retainer 731/720
  • steel retainer 741
  • cup seat 4700/4785
  • shims 4757

Valves: Ferrera Race valves 2.11 intake and 1.77 exhaust.
Pushrods: Comp Cams: 5/16 stock length
Rocker Arms: Crane Silver 1.65


Intake

unmodified RPM performer


Fuel delivery:

Carb: – 1050 Dominator (overkill for this application – 900 would get it done, but this is for keeping up with future upgrades)
Fuel Pump: 140 GPH Mallory Fuel Pump
Fuel line: -8 steel braided lines (½ inch) run from fuel cell in trunk to pressure regulator on firewall to carb. (all STRAIGHT -AN fittings)
Fuel pressure is typically 7- 8 lbs.


Exhaust:

Coated Hooker Super Comps 1 ¾ inch headers, 3 inch collectors. Exhaust is dumped at the track AFTER the Performance Years 3” Pypes X cross over.
Magnaflow mufflers.


Ignition:

GM HEI recurved by Larry Rowe
MSD 6al box
Plug wires: Taylor 8mm


Transmission:

Turbo 400 with reverse pattern Cheetah manual valve body.
Continental 3800 Stall converter
No TRANSBRAKE


Drive shaft:

3 inch tube with 1350 series U-joints


Rearend:

GM 10 Bolt: Spool with 4.10 Richmond gears.


Suspension:

Front: 90/10 Summit drag shocks – no sway bar
Rear: 50/50 Summit drag shocks. Air bags. Boxed upper control arms. Polyurethane bushings all around.
Aluminum body mounts.


Tires:

29.0x12.0-15 GoodYear Eagle Slicks (28 inch tire is better for this application – these tall tires kill gearing, but were too good a deal to pass up)


Car:

1973 Pontiac Lemans
Vehicle Weight: 3500 lbs
Race weight: 3675 lbs
Current HP numbers are 397.8 RearwheelHP and 452.8 RWTQ. Figure 18% loss through drivetrain you 468 Flywheel HP and 533 FlywheelTQ

Graph below.

 

 
 
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