Steve Coombes' 2003 462 Update
Don't be fooled by Steve's detuning effort as his 1970 Trans Am remains a top performer in any class. What is truly wild is that his TA runs as good as it looks. Below are the critical engine and driveline details.
Steve's engine received PSP's 1 to 1 Club honors on June 24, 2004. His engine clearly develops in excess of 1 hp per cubic inch of displacement. It rocks!
| Block | 1970 455 YH |
| Block Specs | + 0.030" over bore; hard block to freeze plugs; Pro-Gram Engineering 4 bolt main caps with ARP studs and bolts. Note: bored and honed to piston manufacturers specs, using torque plate. |
| Bore/stroke | 4.181"x 4.210" 462 cid |
| Heads | Edelbrock #6056 90cc chamber volume (9.7 to 1 static compression); T&D shaft roller rocker system, 1.6 ratio on both valves; ARP head studs & bolts; Felpro 1016 head gasket and 1436 exhaust gasket. Port matched to Specialty Component Engineering intake gasket, 1.175" x 2.320" |
| Head Flow Nos. on SF 600 Bench, 28" of water | .100":83/82 .200":151/145 .300":220/195 .400":270/230 .500":301/248 .600":313/255 |
| Valves | Ferrea 6000 series SS intake:2.15", exhaust:1.77" Lunati H-11 dual valve springs, 1.52" diameter; springs are PolyDyn performance coated |
| Crankshaft | 1970 455 "N", 0.010/0.010 |
| Rods | Carillo 6.625" Forged Steel |
| Pistons | JE forged aluminum |
| Rings | JE ring package with Total Seal top ring. |
| Deck height | +.001 (nominal); Pistons extend .0007 to .0011 above the deck. |
| Bearings | Federal Mogul 3/4 groove mains and Clevite 77 on rods; both Calico CT-1 coated. |
| Timing gear | Rollmaster billet roller 9 key |
| Harmonic Damper | BHJ (SFI approved) |
| Cooling | Meziere Electric (35 gph) |
| Camshaft | Comp Cams Xtreme Energy Street Roller #P4876B/4876B SR108, 254/254 @ 0.050", .389/.389 lobe lift, .622" gross lift with 1.6 rockers, set at 104 degree intake centerline; 108 lobe separation angle |
| Pushrods | Manton 9.150" length, 5/16" diameter x 0.83" wall, 4140 chromoly steel |
| Lifters | Crower solid roller lifter with optional high pressure pin oiler |
| Carburetor/ intake |
Holley 4150 HP950; Edelbrock RPM with plenum divider cut 1"; port matched to heads |
| Oiling System | Canton 6 quart road race pan; Sealed Power 60lb. oil pump; Fram HP2 racing filter, Mobil-1 10w30 synthetic oil. |
| Ignition | MSD system 7AL-3 box; Pro-Billet distributor; HVC coil and crank trigger; Taylor spark plug wires; NGK V-groove plugs |
| Emissions | NA |
| Exhaust | Headman headers 2" tube diameter, 10.5" collectors; 3.5" into 3" Dr. Gas X Crossover; full length 3" exhaust running gases through Dynomax 17792 mufflers. |
| Suspension/ brakes |
Edelbrock IAS shocks on front and rear and front sway bar in place; Landrum 300 lb./ in. leaf springs with Cal Tracs traction bars, Moog 6-cylinder front coiled springs; Wilwood front and rear disc brakes |
| Fuel | Unleaded premium |
| Weight | 3750 pounds |
| Tires/Rims | Front: FirestoneFirehawk SS20 P215/65R15 Rear: 275-60R15 Nitto NT-555R drag radial for street; 28x 12.50 M/T ET Street DOT tires at the strip Rims: American Torque Thrust |
| Driveline features | TCI, internally balanced flex plate (SFI approved); 10" Continental torque converter for the street (8 inch A-1 4200 stall converter for the strip); TH400 transmission with manual valve body; Earl's Performance 19-row transmission cooler; GM 12 bolt with Moser axles, C-clip eliminator; Auburn limited slip with 3.73 to 1 gearing; T/A rear end girdle |
Owner:SteveCoombes
Location:Liberty Hill,Texas
Year:1970
Model:Trans Am
Exterior:Lucerne Blue
Interior:Bright Blue
Performance
Dyno results: 589.1 CB Torque @ 4400 rpms and 580 CB Power @ 5800 rpm
Quarter mile: (running 8" converter and 90/10 shocks on the front and no sway bar in place); 1.60 60" times, 10.88 ET at 124.28 mph (date: 11-21-03)
