| 1st | 14 | Siffert / Redman / Kinnunen | Porsche 917 K | J. W. Automotive Engineering Ltd. | 2:32.770 | 2:34.4700 |
| 2nd | 19 | Andretti / Merzario | Ferrari 512 S Spyder | Ferrari S.P.A., SEFAC | 2:33.500 | 2:33.5000 |
| 3rd | 16 | Elford / Ahrens, Jr. | Porsche 917 K | Porsche Audi | 2:35.420 | 2:35.4200 |
| 4th | 20 | Schetty / Ickx | Ferrari 512 S Spyder | Ferrari S.P.A., SEFAC | 2:36.230 | 2:36.2300 |
| 5th | 15 | Rodriguez / Kinnunen / Siffert | Porsche 917 K | J. W. Automotive Engineering Ltd. | 2:36.310 | 2:36.3100 |
| 6th | T | Siffert / Redman | Porsche 917 K | J. W. Automotive Engineering Ltd. | 2:36.380 | 2:36.3800 |
| 7th | 24 | Posey / Bucknum / Everett | Ferrari 512 S Spyder | N.A.R.T. | 2:36.480 | 2:36.4800 |
| 8th | 21 | Giunti / Vaccarella / Andretti | Ferrari 512 S | Ferrari S.P.A., SEFAC | 2:36.600 | 2:36.6000 |
| 9th | 35 | Gurney / Cevert | Matra-Simca MS650 | Equipe Matra-Elf | 2:37.440 | 2:37.4400 |
| 10th | 31 | Courage / de Adamich | Alfa Romeo T33/3 | Autodelta S.P.A. | 2:38.470 | 2:38.4700 |
| 11th | 34 | Pescarolo / Servoz-Gavin | Matra-Simca MS650 | Equipe Matra-Elf | 2:39.500 | 2:39.5000 |
| 12th | 17 | Herrmann / Lins | Porsche 917 K | Porsche Audi | 2:40.320 | 2:40.3200 |
| 13th | 32 | Stommelen / Galli | Alfa Romeo T33/3 | Autodelta S.P.A. | 2:40.780 | 2:40.7800 |
| 14th | 33 | Hezemans / Gregory | Alfa Romeo T33/3 | Autodelta S.P.A. | 2:41.370 | 2:41.3700 |
| 15th | 22 | Parkes / Parsons | Ferrari 312 P Coupe | N.A.R.T. | 2:42.190 | 2:42.1900 |
| 16th | 48 | McQueen / Revson | Porsche 908/02 Flunder | Solar Productions, Inc. | 2:42.750 | 2:42.7500 |
| 17th | 23 | Adamowicz / Chinetti, Jr. | Ferrari 312 P Coupe | N.A.R.T. | 2:43.100 | 2:43.1000 |
| 18th | 47 | Laine / van Lennep | Porsche 908/02 | Racing Team AAW | 2:44.170 | 2:44.1700 |
| 19th | 45 | Attwood / Larrousse / Koch | Porsche 908/02 | International Martini Racing Team | 2:46.430 | 2:46.4300 |
| 20th | 27 | De Udy / Hailwood | Lola T70 Mk.3B GT Chevrolet | Grand Bahama Racing Car Co. Ltd. | 2:50.710 | 2:50.7100 |
| 21st | 30 | Forester / Hedges | Ford GT40 | Trevor Graham | 2:52.200 | 2:52.2000 |
| 22nd | 61 | Baker / Baker / Richards / Rinzler | Chevron B16 Ford | Ring Free Oil Racing Team/Baker Motor Co. | 2:54.730 | 2:54.7300 |
| 23rd | 26 | Brown / Young / Ormes | Lola T70 Mk.3B GT Chevrolet | Randy's Auto Body | 2:57.060 | 2:57.0600 |
| 24th | 2 | Thompson / Mahler | Chevrolet Corvette | Troy Promotions, Inc. | 2:57.360 | 2:57.3600 |
| 25th | 62 | Robinson / Kleinpeter | Chevron B16 Ford | Chevron Cars | 2:59.020 | 2:59.0200 |
| 26th | 1 | DeLorenzo / Lang | Chevrolet Corvette | Troy Promotions, Inc. | 2:59.680 | 2:59.6800 |
| 27th | 29 | Heppenstall / Grant | Ford GT40 | Auto Enterprises | 3:00.180 | 3:00.1800 |
| 28th | 4 | Greenwood / Barker | Chevrolet Corvette | John Greenwood | 3:00.230 | 3:00.2300 |
| 29th | 3 | Johnson / Johnson / Greendyke | Chevrolet Corvette | Doug Bergen Racing | 3:02.840 | 3:02.8400 |
| 30th | 5 | Schumacher / Petree | Chevrolet Corvette | Wm. A. Schumacher | 3:03.075 | 3:03.0750 |
| 31st | 41 | Bock / Dent | Chevrolet Camaro | Laurel Racing (Larry Drover) | 3:06.600 | 3:06.6000 |
| 32nd | 9 | Grossman / Yenko | Chevrolet Camaro I | Marlbank Racing Team | 3:06.890 | 3:06.8900 |
| 33rd | 43 | Tremblay / McDill | Chevrolet Camaro I | Bruce Behens Racing | 3:07.150 | 3:07.1500 |
| 34th | 40 | Gimondo / Dietrich | Chevrolet Camaro I | Takondo Racing | 3:07.380 | 3:07.3800 |
| 35th | 50 | Rahal / Wise / Frank | Porsche 906 | Nationwide Food Brokers Racing Team | 3:07.400 | 3:07.4000 |
| 36th | 8 | Heinz / Costanzo | Chevrolet Corvette | Or Costanzo | 3:07.470 | 3:07.4700 |
| 37th | 51 | Behr / Rosen | Porsche 906 | Porsche Audi VWNC | 3:11.600 | 3:11.6000 |
| 38th | 38 | Kearney / Chitwood / *Boo / *Floyd / *McClain | Chevrolet Camaro | David H. McClain | 3:14.710 | 3:14.7100 |
| 39th | 25 | Cluxton / Pickett | Ferrari 275 GTB/C | Harley E. Cluxton, III | 3:15.940 | 3:15.9400 |
| 40th | 49 | Greger / Schmalbach | Porsche 910 | Josef Greger | 3:16.550 | 3:16.5500 |
| 41st | 67 | Bandy / Stevenson | Lotus 47 | Sport Motors | 3:17.030 | 3:17.0300 |
| 42nd | 54 | Arutunoff / Pryor | Abarth 2000 SP (SE010) | Automobiles of Italy, Inc. | 3:17.130 | 3:17.1300 |
| 43rd | 92 | Gwynne / Elliott | Chevrolet Camaro I | Preston Hood Chevrolet, Inc./John Elliott | 3:17.380 | 3:17.3800 |
| 44th | 63 | Fabre / Aguilar | Chevron B8 BMW | Carlos Fabre | 3:18.010 | 3:18.0100 |
| 45th | 53 | Gregg / Harrison | Porsche 911 T | Brumos Porsche Audi Corp. | 3:18.330 | 3:18.3300 |
| 46th | 39 | Kemp / Mitchell | Chevrolet Camaro | Robert B. Mitchell | 3:19.030 | 3:19.0300 |
| 47th | 77 | Jennings / Tullius | Porsche 911 T | Bruce Jennings | 3:19.970 | 3:19.9700 |
| 48th | 91 | Corwin / Mims | Chevrolet Camaro I | Flem-Cor Enterprises | 3:21.980 | 3:21.9800 |
| 49th | 37 | Collins / Wilson | Ford Mustang | Collins-Wilson Racing | 3:22.780 | 3:22.7800 |
| 50th | 52 | Duval / Bailey / Nicholas | Porsche 911 T | Jacques Duval | 3:23.100 | 3:23.1000 |
| 51st | 73 | Guthrie / Smith / Kondratiff / *Seavey | Austin-Healey Sprite | Ring Free Oil Racing Team/Baker Motor Co. | 3:24.200 | 3:24.2000 |
| 52nd | 36 | Cuomo / Gimbel / Lisberg | Ford Mustang | Ray Cuomo Racing | 3:26.360 | 3:26.3600 |
| 53rd | 12 | Roethel / Bentley | Ford Mustang Boss 302 | BRM Inc. | 3:27.810 | 3:27.8100 |
| 54th | 74 | Meaney / Bean | Porsche 911 T | Ralph Meaney, Inc. | 3:28.290 | 3:28.2900 |
| 55th | 59 | Smith / Donley / Buttari | MG Midget | Waldron Motors | 3:28.940 | 3:28.9400 |
| 56th | 81 | Kennedy / Samm / Tillson | Lancia Fulvia HF | Texas Speed Museum | 3:30.310 | 3:30.3100 |
| 57th | 7 | Morehead / Vega | AMC AMX | Bruce Morehead Racing | 3:30.340 | 3:30.3400 |
| 58th | 56 | Woodner / O'Connor | MG Midget | British Leyland Motors Inc. | 3:32.680 | 3:32.6800 |
| 59th | 57 | Belperche / Gammon / Mummery | MGB | Waldron Enterprises Inc. | 3:34.260 | 3:34.2600 |
| 60th | 55 | Brennan / Blackburn | MGB | British Leyland Motors Inc. | 3:34.600 | 3:34.6000 |
| 61st | 58 | Scott / Houser / Lanier | MGB | Waldron Enterprises Inc. | 3:39.570 | 3:39.5700 |
| 62nd | 82 | Clark / Marsula | Lancia Fulvia HF | General Plastics | 3:39.620 | 3:39.6200 |
| 63rd | 80 | Kennedy / Tillson / Samm | Lancia Fulvia HF | Texas Speed Museum | 3:43.180 | 3:43.1800 |
| 64th | 97 | Brown / Marcus / Sandman | BMW 2002 | HCAS, Inc. | 3:45.380 | 3:45.3800 |
| 65th | 79 | Taylor / Dyer | Alfa Romeo 1750 GTV | Del Taylor | 3:46.790 | 3:46.7900 |
| 66th | 18 | Pettey / Hallquist | Ford Mustang | Paul Pettey | 3:47.090 | 3:47.0900 |
| 67th | 87 | Whitaker / Eckoff / Slottag / *Davidson | Volvo 122 S | Robert W. Whitaker | 3:47.170 | 3:47.1700 |
| 68th | 60 | Kilpatrick / Goodrich | MGB | Herrington Motors | 3:51.100 | 3:51.1000 |
| 69th | 86 | Polimeni / Theall | Volvo 122 S | Sandy's Spares | 3:52.380 | 3:52.3800 |
| 70th | 88 | Fleming / Johnson / Bowers | Fiat 124 Coupe | Simone N. Fleming | 3:53.240 | 3:53.2400 |
| 71st | 69 | Spruell / Pickett / *Theodoracopulos | Alfa Romeo Giulia Spider | Scuderia Spruell | 3:57.900 | 3:57.9000 |
| 72nd | 85 | Cooper / Mosher | Opel Rallye | HCAS, Inc. | 4:04.710 | 4:04.7100 |