Oldsmobile 455 Big Block Engine Build - 511-LB-FT, 445HP 455 Rocket Olds

With our Rocket 461-inch motor assembled, it will be an easy evening's work to swap in our lighter and more powerful Edelbrock aluminum-headed 461ci thruster using a set of coated 1 3/4-inch Dick Miller Racing headers.

With our Rocket 461-inch motor assembled, it will be an easy evening's work to swap in our

On the street, torque is king. One of the best and simplest ways to make gobs of frame-twisting torque is with cubic inches. Among the torque kings in the GM world are the Buick, Pontiac, and Olds 455ci twisters, but it's often the Olds that wins out. While the good Dr. Olds factory variants have been the staples of Rocket performance building for decades, Edelbrock's aluminum head contribution has made building one of these big-blocks enticing and weight conscious. So when it came time to freshen up the tired 455 in our budget '64 F-85 Olds project, we learned a few assembly tricks for our fat-block we thought we'd pass along that will ensure our Olds lives a long and prosperous life-and makes some acceptable power, too.

The plan was a much more street-conservative approach versus our usual max-out horsepower effort-more of an everyman's big-block. We wanted a daily-driver engine with pump-gas-friendly compression and a Comp flat-tappet hydraulic cam to enhance the Olds' already legendary torque. We really enjoy cruising the F-85 with its patina paint, so future plans include either a tight converter combined with a California Performance Transmissions 200-4R overdrive automatic, or maybe we'll retain the TH400 and just slip a 2.56:1 rear gear behind it. Either way, our recipe called for a motor that would make stupid low-speed torque while still pushing our F-85 to mid-12 quarter-mile times. All this was also with an eye toward not destroying what was left of our meager car budget.

After cleaning the block, Barrington bored the block 0.030 over and torque-plate-finish-honed each cylinder to fit the 4.155-inch-bore-size hypereutectic pistons.

After cleaning the block, Barrington bored the block 0.030 over and torque-plate-finish-ho

Since we had never assembled an Olds motor before, we relied heavily on advice and assistance from Don Barrington at Barrington Engines and Dick Miller Racing (DMR), whose Mississippi-based shop offers tons of options for the Rocket engine builder. Barrington and Miller helped us avoid the common assembly mistakes on our 461ci street engine, and much of the success of this engine is due to their significant contributions.

Search and Destroy
While it would have been cheaper to rebuild the existing 455 in the '64 F-85, we knew the build would take some time, and we wanted to continue to drive the car. We found a used 455 short-block on Craigslist that got us started. The crank was wasted, but for $200, we bought the short-block and an extra crank that we discovered had a trashed thrust surface. Engine and Performance Warehouse in Anaheim, California, repaired our ailing crank and gave it a perfect 0.010-under treatment. We then took the block, crank, rods, and pistons to Barrington Engines where Don Sr. and Don Jr. cleaned, bored, and torque-plate-honed the aging jet-boat motor. West Valley did the balancing act.

One trick Barrington and Miller suggested was replacing the stock Conestoga wagon-era rope rear main seal with a neoprene lip seal from a 460 Ford. Next, the guys encouraged us to add cam bearing restrictors that direct more oil to the mains. Our next surprise came with the rear main bearing clearance measuring a wide 0.0041 inch. Barrington says this was factory intentional to flood the rope seal with oil to prevent it from overheating. Barrington suggested we retain the clearance because it would require expensive line boring to repair, so we followed his advice. We've also outlined a couple of other Olds-specific assembly techniques that can save you some grief when assembling a street Rocket.

Edelbrock Aluminum Heads
Our own flow testing and DMR's experience showed us that the off-the-shelf Edelbrock aluminum Performer RPM heads flow about the same as a set of factory iron C heads. This limited flow is partly due to the requirement that the ports (especially the exhaust) remain in their stock locations. We wanted to improve on the intake flow slightly without spending big bucks for CNC porting, so we tried the classic 30-degree back-cut trick on the Edelbrock valves, which netted a minor flow improvement. The Edelbrock heads measure 77 cc and combined with the 15cc dished KB pistons create a 10.2:1 static compression.

Flow Chart
Edelbrock Performer RPM Olds Aluminum Head
2.07/1.68-inch valves (PN 60519 complete)
77cc chamber
188cc port

A simple 30-degree back-cut on the Edelbrock intake valves was worth as much as 12 cfm at 0.400-inch valve lift. The production 455 head we tested at 0.400-inch valve lift flowed only 190 cfm. Our modified Edelbrock's amazing 56-cfm flow improvement at 0.400-inch valve lift is a 29 percent gain over the stock heads.

Cam Specs

Test Day Edelbrock agreed to help us with the dyno testing, and Edelbrock dyno veteran Curt Hooker bolted our 461ci Rocket to the company's SuperFlow dyno. Before firing the engine, we pressure-lubed it with a homemade tool that really was nothing more than a 6-inch-long Allen bolt. The bolt head is used to spin the hex drive oil pump driveshaft. After properly timing the Performance Distributor D.U.I. HEI distributor, Hooker carefully broke in the Comp flat-tappet camshaft for roughly 20 minutes using Royal Purple's 10W-30 break-in oil.

Test Day
Edelbrock agreed to help us with the dyno testing, and Edelbrock dyno veteran Curt Hooker bolted our 461ci Rocket to the company's SuperFlow dyno. Before firing the engine, we pressure-lubed it with a homemade tool that really was nothing more than a 6-inch-long Allen bolt. The bolt head is used to spin the hex drive oil pump driveshaft. After properly timing the Performance Distributor D.U.I. HEI distributor, Hooker carefully broke in the Comp flat-tappet camshaft for roughly 20 minutes using Royal Purple's 10W-30 break-in oil.

Big-block Olds engines are famous for making torque, and this combination was no exception. Even at a mere 2,500 rpm, the Olds cranked out nearly 490 lb-ft, then went on to grunt out a solid 511 lb-ft at 3,700 rpm, and still managed to make a solid 445 hp at 5,000 rpm. The torque was expected, and we hedged our bet a little by trying the Edelbrock Torker single-plane intake to see if we could give the horsepower a bump. If you look closely at the torque numbers, you can see a slight dip in the curve between 3,800 and 4,500 rpm that may be due to a combination of the single-plane intake and the large 2.00-inch dyno headers. We would expect some if not all of that dip to disappear in the car with the use of our Dick Miller 13/4-inch headers and a muffled Flowmaster exhaust. We'd like to thank Edelbrock and specifically Curt Hooker for his time, expertise, and the benefit of his expansive experience that made our dyno flog much easier. Real-world dyno numbers are always better than best guesstimates. Overall, the effort was a great success, and now all we have to do is drop it into our '64 F-85 and enjoy all that torque.

Dyno Results

Parts List

*These components could be deleted from the buildup to save money. Subtracting these parts from the overall cost would reduce the price by $627.85.
**This price includes Edelbrock's $50 rebate. Plus, you get a couple of Edelbrock T-shirts, too!