The Big-Block Olds Lives On With Rocket Racing’s Killer Casting

When it comes to Oldsmobile performance there are two things that are known. One: if you want solid, reliable power with an Oldsmobile powerplant, Rocket Racing and Performance is one of the leaders in the Oldsmobile performance game. Two: if you want big power numbers from an Olds, you’re going to be in for a project, as the stock blocks are getting harder and harder to find, and when you do find them, you’re rolling the dice. Thanks to Rocket Racing and their new aftermarket Oldsmobile block, the first is truer than ever, while the latter is no longer a factor.

The Birth Of A Block

When you talk about a big-block in a performance application–especially with aftermarket components–making big power isn’t a problem. However, when talking about a big-power Oldsmobile, previously there were two options: to use an OEM tall-deck block with a main stud girdle and cross your fingers, or run a non-Oldsmobile engine. For more information, we consulted with John Stolpa, of Rocket Racing and Performance.

“Until now, there’s never been an Olds aftermarket block on the market,” he says.

“We not only needed something more robust for our projects here at the shop, but the market demand was there for a solid performance Oldsmobile block option. Plus, there are people who want an all-new engine for their car, and the block was really the last thing that didn’t exist. Every other part was available through the aftermarket.”

One of the key features of the Rocket Racing Block’s wildly-increased strength over OEM is its redesigned architecture. Even at the listed maximum bore size of 4.400 inches, there is still .200-inch cylinder wall thickness. Couple that with the additional strength of the CGI variant, even thinner walls can be safely run for previously-unheard of Oldsmobile bore sizes and displacements.

The OEM block is fine for a stock restoration or mild performance build, but how many of us are happy with just “mild”?

“Our cylinder heads and intakes alone are capable of making power far exceeding what the OEM blocks can handle,” says John.

“You can put on aftermarket main caps, and run girdles and all that stuff. Even when you add that, the stock block still can’t handle what is available to make horsepower today. Not to mention that everyone wants more cubes these days. And with the stock blocks, you just can’t open them up enough to get the cubes people want from an Olds.”

By now, you’re probably wondering what kind of power levels we’re talking about with respect to power level and material failures when using an OEM block.

“It’s tricky to say exactly where the stock block’s limits are, because you can have one guy who breaks his block at 550 horsepower because he didn’t have his tune-up right, and then another who really knows what he’s doing living at 700,” John says.

“From what we’ve seen here, with the girdles and a good tune-up, you’re limited to about 800 horsepower, naturally-aspirated. Keep in mind, that is with all the band-aids possible on a stock block.”

Holding It Together

Coming from a drag racing background, there is another performance aspect that is at the front of John’s mind, and that’s durability.

“In addition to the power levels, there’s also longevity to consider. Some guys will make three passes a year on a car, so [the OEM block] may live for quite a few years,” John says.

“For us, a year consists of 150-200 passes on an engine. So really, that’s our standard for use in a year’s time. We come from bracket racing with quick turnarounds and lots of events. At one point in time, our track had 32 events in a year, so we know what it takes for an engine to survive in a severe-duty environment.”

A common strength upgrade to the OEM block, four-bolt billet steel main caps come standard at all five positions on the Rocket Racing block.

Starting with better materials, the Rocket Racing Olds blocks are cast in two separate versions; the standard is a proprietary iron alloy, with a Compacted Graphite Iron (CGI) version for those looking to make ridiculous power numbers on a regular basis.

“With all the stuff we have incorporated into this block, I don’t see why we couldn’t push it to 3000-plus horsepower in the regular iron,” John says. “CGI is supposedly 75-percent stronger, given all the same thicknesses and design specs as a grey iron counterpart. If you do the math – 3000 horsepower and add 75-percent – that’s a lot of horsepower.”

Differences Count

Designing a block to handle insane power levels comes from more than just using a better alloy of iron during the manufacturing process. To start, John made sure all the critical thicknesses of the block were stout enough to handle extreme conditions, regardless of bore or stroke used. The cylinder wall thickness is at least 0.200-inch even with a 4.400-inch bore (the stock 455 bore is 4.125-inch, for comparison).

The deck thickness is increased for any form of power adder use you can imagine, and the deck comes with a surface finish capable of being used with MLS gaskets, out of the box. The block comes standard with blind holes threaded for a 1/2-inch head stud, with the option to upgrade to a stout 9/16-inch head stud.

The bottom of the cylinders come clearanced from Rocket Racing for a 4.5-inch stroke with an aluminum connecting rod. However there is enough meat on the barrel to safely remove enough material to go to a 4.850-inch stroke.

The cylinder skirts are clearanced from the factory for a 4.500-inch stroke, but more can be achieved with additional machining. “When we originally set the clearances, we had a 4.500-inch crank in there with an aluminum GRP big-block rod,” Says John. “The only thing that will limit you on how much clearance you can put into it is going to be camshaft height. We have a pretty big barrel down there, so you could probably go 4.800- or even 4.850-inch in there.”

A common upgrade on the OEM blocks is billet main caps, so it only stands to reason that billet main caps are incorporated into this block, along with a stronger main web design. All five main caps are billet steel, four-bolt pieces, and are sized for standard big-block Oldsmobile main bearings.

The Rocket Racing block comes with .842-inch lifter bores as standard. However, like everything else on this block, they were designed with the ability to be enlarged up to a whopping 1.00-inch bore for severe-duty applications.

Potentially the largest change in order to increase longevity of the combination is the redesigned oiling system, going to a true priority main configuration. However, the priority main system does bring about one unavoidable compatibility issue.

“Instead of having the OEM Olds system where the oil comes in on the cylinder wall side of the lifter bore, now the oil galley runs front to back,” says John.

With the redesigned priority-main oiling system in the block, redesigned Rocket Racing solid-roller lifters need to be used. However, the issue is only with solid-rollers. Standard hydraulic flat-tappet and roller lifters, along with standard solid flat-tappet lifters will work out of the box.

That modification is the one feature of the block that requires non-standard parts to work, as a standard solid roller Olds lifter won’t work.

“With the clocking of the oil hole in a standard Oldsmobile solid lifter, there’s no restriction, and it will blow oil straight up into the cylinder head,” John says. “It’s only different when using a solid roller lifter. If you are using a hydraulic flat or roller lifter, then those drop right in.”

Even with the redesigned oiling system, Rocket Racing is able to retain the use of an OEM big-block Olds oil filter thanks to the included filter adapter.

“When we built this block, we took a look at all of the problems of the factory blocks and fixed them. Then we also added durability enhancements to make it live on the race track,” John says. “That’s the beauty of this block: it works for the street or the track. We fixed the oiling issues and added all the features to make it work in a specialty application, but you can also bolt on all of the parts from your stock engine right onto this block. There is one block design and it works for every application you can throw at it.”

The Universal Soldier

The final touch that makes the Rocket Racing block the ultimate Oldsmobile engine block, is the universal bellhousing pattern. While not actually universal, the block is cast and threaded to accept Oldsmobile, Buick, Pontiac, Cadillac, and Chevy pattern bellhousings. “Using a non-Oldsmobile transmission is getting to be more common as more and more people want an overdrive or want to put a Tremec in the car,” John says. “There are all kinds of automatic swaps that are exploding in popularity, like the 4L80E and the 700R4.”

The “universal” bellhousing bolt pattern on the back of the block allows for the use of Buick, Olds, Pontiac, Cadillac, and Chevrolet bellhousings, allowing for simplified upgrades to more common modern transmissions.

In addition to easy and readily-available overdrive transmissions for Olds-powered street cruisers, the multiple bellhousing pattern is also a benefit to the racers in the crowd. There’s not a lot of SFI-approved stuff out there right now, readily-available for the B.O.P. bellhousing pattern,” says John. “A B.O.P. owner building something for the track usually has to deal with an upcharge for the B.O.P. pattern and then deal with the lead time while it’s custom-made.”

Rocket Racing also makes all the different components needed to build your big-block Oldsmobile into a big-cube powerhouse. With their 4.250 or 4.500-inch billet cranks and 4.40-inch pistons on the shelf, you can easily get between 517- 548 cubic inches out of their block. If you want to order custom parts, 600-plus cubic inches is an attainable goal.

While it may have been a long time coming for the Oldsmobile enthusiasts, there is now a comprehensive all-in-one aftermarket solution for anyone wanting to run an aftermarket Oldsmobile big-block engine. Whether you want to recreate the 455 that came in your Olds from the factory using all-new parts, or if you want to build an Olds-powered Pro Mod, this aftermarket block can handle that, and everything in between, with the ability to go to over 600 cubic inches.

The Oldsmobile marque may have gone to the great automotive graveyard in the sky, but thanks to the efforts of companies like Rocket Racing and Performance, its legacy lives on!

Article Sources

About the author

Greg Acosta

Greg has spent over a decade in automotive publishing as Senior Editor of Race Pages magazine. In his free time, he is a firearms instructor and volunteer in the police armory.
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