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Olds 455 Big Block - Project Murderous Overkill Part VI

Christian Hazel
| Brand Manager, Four Wheeler
Posted April 10, 2008
Photographers: Courtesy of Mondello Performance Products

The Mondello Monster

With a name like Project Murderous Overkill, did you think we were gonna puss out on the engine? The Olds 455 is legendary for its huge grunt, oozing character, and its relative ease to find in the junkyard. It makes a great performer either straight out of the four-door luxo barge or totally built-up. We went for the latter.

If you tuned in last issue, you saw our naturally aspirated dyno numbers of 544 hp at 5,700 rpm and 568 lb-ft of torque at 4,400 rpm with more than 500 lb-ft of torque on tap from 3,400 rpm through 5,700 rpm. With a Zex nitrous system, we scratched at 700 hp and 770 lb-ft of torque, so our combo is no slouch. (Editor's note: check for dyno videos.) It may seem sycophantic, but we've got to give a big shout out to a few companies that really make a project like this come together successfully.

If there's one name synonymous with Oldsmobile Performance, it's Joe Mondello. He literally wrote the book on the subject. His "Oldsmobile V-8 Technical Reference Manual" is the only such publication to actually carry a GM part number (PN 1248002027), and 40 years ago, he blueprinted the oiling system and valvetrain for the Oldsmobile Motor Division. It's safe to say there's no better place to go for competent Olds knowledge and experience. Nowadays, Joe is semiretired, so we hooked up with the general manager of Mondello Performance Products, Lynn Welfringer, for an Olds big-block combo that would rattle the world when we line up at the bottom of a dune or the quarter-mile.

Competition Cams is constantly at the forefront of technology, testing and analyzing profiles, grinds, and combos. The company and its subsidiaries strive to maintain the highest-quality standards and are always looking for new and unusual ways to eke out more power with little to no trade-offs (the Zex perimeter nitrous plate is a good example). Yet they do this without degrading customer service. Curly Schmo can still call up and order a custom-grind camshaft and have it no later than a big-name engine builder.

Finally, Edelbrock is a huge supporter of American hot rodding, not only in its broad range of applications (the company has everything from Cadillac to Chevy to Buick covered), but most impressively, Edelbrock still maintains its manufacturing right here in the USA. A privately held company, the Edelbrock family invests in its employees, its product, and its country, dammit!

Read on for our Olds Pro Street combo that will serve our '48 Willys pickup dutifully, scare small children with open exhaust, and strike fear into the hearts of the import nation.


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When choosing an Olds core, the 455 will have "396021 F" or "396021 Fa" cast in the front of the block between the manifold and the water pump. Sonic checking is required to overbore out to 0.120-inch, but Mondello simply cleaned up our block with a 0.060 cut before expertly honing the bores.

Like most luxury-car-sourced V-8s, the Olds oils the valvetrain first, then the bottom end. It's good for the doctor who didn't want to hear valvetrain clatter in the morning on the way to the hospital, but bad for high-rpm and performance use. Mondello knows all the tricks to keep an adequate supply of oil downstairs for the main and rod bearing.

Edelbrock came on the scene with a vengeance a decade ago with its line of Performer, Performer RPM, and Victor series aluminum cylinder heads for nearly every brand of modern American V-8. The Performer RPM Olds heads are a much-improved design compared with even the best factory castings. The Edelbrock heads feature 2.07-inch intake and 1.68-inch exhaust valves, springs good for cams up to 0.575 lift, 77cc combustion chambers, relocated plug locations, and out of the box they flow a minimum 258-cfm intake/183-cfm exhaust at 0.600 valve lift. Mondello takes a great head and makes it better.


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Westech Performance Group
Mira Loma, CA
Comp Cams
Memphis, TN 38118
Performance Distributors
Memphis, TN 38132
Memphis, TN 38118
Barry Grant
Dahlonega, GA 30533
Mondello Performance Products
Paso Robles, CA 93446
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