Bill Boyle's 400 Rebuild

My goal was to build a powerful but reliable low compression street do it right the first time and to keep emissions in proper perspective.

Car: 1979 Trans Am with TA/6.6--400 engine--an original L-78/W-72 220 net hp engine with 6X-4 heads and 1 compression

Technical Data
Link to Bill's narrative

  • Bore and stroke--4.15" x 3.75"--bored .030 to accommodate forged pistons with moly rings; journals align honed
  • Heads--stock 6X (6x-4) heads--3 angle competition valve job retaining original 2.11" and 1.66" valves; valves reconditioned; bronze valve guides; heads surfaced to 94 cc's
  • Crankshaft--reconditioned .020 undersize; journals polished
  • Rods--stock reconditioned with ARP bolts
  • Pistons--TRW forged +.030; deck height averages .0065" +/- .001" on each cylinder
  • Rings--moly--Sealed Power (Federal Mogul) SP E-299K 30
  • Main Bearings/Rod Bearings/Cam Bearings--Michigan (Clevite77)
  • Timing Gear and Chain--Edelbrock 3-key way true roller (PN 7812)
  • Camshaft--Comp Cams 270H; .476" lift Intake/Exhaust; 224/ 224 degrees duration (fair idle, good low and mid-range torque); cam is "straight-up" at 106 degrees.
  • Valve Springs--Crower; shims on intake to get proper installed height
  • Rocker Arms--Comp Cams--Magnum Roller Rockers (1.52) Link to rocker adjustmentwith 7/16" rocker studs (ARP) and 7/16" poly lock nuts with set screw (Mr. Gasket) #921
  • Retainers--OEM
  • Keepers--OEM
  • Valve Seals--umbrella type
  • Lifters--Comp Cams (PN 852-16)
  • Push Rods--moly--Comp Cams (PN 7262-16)
  • Gasket Set--Fel Pro--(note this engine used 5 tang rear seal)
  • Carburetor--1979 Stock Quadrajet (rebuilt original)
  • Intake Manifold--Stock OEM for L-78/W-72 (restricted secondaries)
  • Emissions--No EFE; all other stock devices retained including EGR
  • Exhaust manifold--Hooker Super Competition Headers 1.75" primaries; 2.5" pipes
  • TransDapt remote oil filter--uses AC PF-2 filter; Aeorquip braided lines/fittings
  • All reciprocating parts are balanced; all tolerances meet OEM specifications

Note: These components work well with 4 speed; 3.23 gears to 3.73. More gear is impractical for street use unless gas consumption is completely unimportant. This low compression engine runs on pump gas.

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