Super Stock Hemi Engine Build - Rebuilding A Legend
We're asked to build the engine for a True Sox & Martin Hemi 'cuda.
From the December, 2011 issue of Mopar Muscle
By Dave Young
Photography by Dave Young
To properly depict the historical significance of a nostalgic race car, we must first take ourselves back to the time when these cars were originally campaigned at racing events. Though automobiles have likely been raced since the second one was produced (the first car could only race carriages), public interest in racing, and specifically drag racing, arguably saw its best years during the late '60s through early '70s. It was during this time that many dragstrips opened across the country, and domestic auto manufacturers recognized the American public's greed for power and enjoyment of the sport of racing. All of the Big Three were involved, engineering and manufacturing cars with the specific purpose of winning the Stock classes of both drag racing and oval track venues. The phrase, Win on Sunday, sell on Monday was coined during this period, and it was a time of growth and transition for the sport of auto racing. It's not often that we get an opportunity to work on a piece of Mopar history, but this month we're building a Super Stock Race Hemi for a Sox & Martin '68 Barracuda that is now owned by Todd Werner of central Florida.
The history of each brand of American automobile is varied and unique, but no car manufacturer was more closely tied to racing during the '60s and '70s than the Chrysler Corporation. Relying heavily on the practice of hiring creative and enthusiastic engineers, Chrysler's Dodge and Plymouth divisions carefully interpreted the rules of the major sanctioning bodies, designing cars and engines specifically to dominate the top classes of drag and stock car racing, which were both growing exponentially during this time. It can be argued, in fact, that Chrysler did too good a job of designing and building these cars, and supporting their teams, as evidenced by Dodges and Plymouths being handicapped by sanctioning bodies, especially when powered by the 426 Hemi engine.
Of the many historical Mopars developed by Chrysler during this period, there was one specific program which would change the history of drag racing and define class dominance. In late 1967 a program was launched by Chrysler, called Special Vehicle Development. The task: to design an A-Body drag racing package around the Dodge Dart and Plymouth Barracuda fastback. Chrysler engineer Tom Hoover directed the program, assigning Robert Tarozzi to build a working prototype using a '67 Barracuda with '68 trim and the 426 Hemi, to run in the Super Stock/B (SS/B) drag racing class.
After development and testing proved the A-Body package cars were capable of mid ten second elapsed times, Chrysler contracted the Hurst Corporation to specially build a limited number (150 is commonly accepted) of Dodge Darts and Plymouth Barracudas. Assembled with fiberglass front body components, thinner than stock glass, special suspension, and a cast-iron headed Race Hemi, these cars were available to the public, but specifically directed at race teams who would refine them to dominate the class of Super Stock (SS)/B, SS/A, and now SS/AH. One of the teams to successfully campaign several of these purpose-built Plymouth Barracudas during the early years of Super Stock was the team of Ronnie Sox and Buddy Martin.
As the driver of the Sox & Martin Plymouths, Ronnie Sox was known for his prowess with a four-speed manual transmission, driving factory-backed Plymouths in multiple classes of Stock and Super Stock Eliminator including '68 Barracudas campaigned in Super Stock/B. As Super Stock racing evolved and the cars got faster, sanctioning bodies created a new class of drag racing for the 1970 season, Pro Stock, which has remained one of the most popular drag racing classes today.
After winning the 1969 NHRA and AHRA World Championships in Super Stock, Ronnie Sox won the inaugural 1970 season of Pro Stock in a Jake King and Dave Christie-prepped four-speed Hemi 'Cuda, then backed it up in 1971 with another World Championship, earning the best driving record of the 1970 to 1972 four-speed era by winning 9 of 23 events. But as the Hemi engine showed dominance in Pro Stock, the sanctioning bodies began adding weight to Hemi-equipped vehicles, leading Chrysler to direct its factory sponsored teams to boycott the class for the 1974 season in protest of the handicap.
Not wanting to lose his edge as a racer, Ronnie asked his contacts at Chrysler how he could continue racing, and was instructed the team could maintain factory backing while running Super Stock in one of the Hurst-built '68 Hemi Barracudas. Buddy Martin quickly acquired a car, and it was modified by Dave Christie who added a new rear suspension to support the Dana 60 and a thicker rear glass to replace the thin Corning glass per Chrysler's instructions. Jake King then built the Hemi for the '68 Barracuda to class specifications, and Ronnie Sox drove the car during the 1974 season, earning a win at the Gator Nationals.
Acquired several years ago by the Pro Toyz collection, this Barracuda is an exceptionally clean and well-restored race car, with a period correct 426 Hemi engine and many unique Sox & Martin-specific pieces in the rear suspension, under the fiberglass lift-off hood, and throughout this well-built piece of racing history. Unfortunately, the engine was not the original Super Stock Race Hemi, and since it exhibited signs of wear including low oil pressure, oil and coolant leaks, and smoke, Pro Toyz curator Chuck West decided it was time for a rebuild and gave us a call to discuss the project.
Any time you or your local machine shop rebuilds an engine, or builds one from scratch, it is very important to define the purpose of the vehicle. As a highly collectible race car, and one of the original '68 Hurst-built Barracudas, we knew this car was too valuable to risk making a pass down the strip with a race engine, no matter how tempting it would be. This Plymouth is primarily a display piece, though it does get driven on occasion (that's right, on the street) and you've likely seen it at the Mopar Nationals or other events as Todd enjoys sharing his collection with the public. So while a full-blown Super Stock race engine didn't make sense for this vehicle, we wanted to do the car justice with a well thought out combination that would look period correct, with enough power to make Ronnie and his team proud.
Although this Hemi did run prior to being removed, the more we inspected the parts, the worse things kept getting. The already .040-inch under crankshaft had spun bearings, rendering it useless, and we found that the block was cracked and repaired, but the poor repair and .060-inch overbore rendered the block useful only as a display piece. Additionally, both cylinder heads were cracked between the valves and the spark plug hole, as well as in the water jackets, making it necessary to replace them. After our complete inspection, the only pieces we had that were serviceable were the connecting rods, valve covers, oil pan, and the proper cross-ram intake manifold.
Though cracked and broken parts are not uncommon, the number of broken pieces in this engine had us scrambling for replacement parts. Knowing we needed original parts to maintain a period correct look, a rebuildable factory block with a casting date of June 10, 1968, was located. Chuck also located several pairs of cylinder heads, which we tested until we found two good heads to build. With the major pieces in place, we moved on to the rotating assembly.
Because this engine will never see a full-throttle pass down the dragstrip or be inspected by NHRA tech crews, the specifications won't have to adhere to rules outlined for Super Stock competition. With this in mind, we knew that the owner of this car wanted a stout, high-compression Hemi and only ran race fuel in the car, so we ordered a set of Keith Black forged 12.5:1 pistons. Milling the heads combined with a Scat 4.15-inch stroke crankshaft will provide additional squeeze, netting a true compression ratio of more than 13.0:1. With a roller cam, lifters, and matching valvesprings from Comp Cams, stainless steel Manley valves, Indy rockers, a Milodon oil system, and rings and bearings from Summit Racing Equipment, we look forward to assembling and installing this engine in a future issue of Mopar Muscle. For now, however, we'll be taking extra care as we remove and inspect the engine of this historic Mopar race car.
There are certain historical...
There are certain historical cars associated with our hobby that are immediately recognizable to most Mopar enthusiasts, like the red, white, and blue Sox & Martin Hemi Barracudas campaigned in Super Stock and Pro Stock drag racing classes. This month we get the honor of building the Hemi for one such ’68 Cuda.
1a Known as the “protest”...
1a Known as the “protest” or “boycott” car, this particular Plymouth was purchased and prepped by the team for the 1974 season of Super Stock...
1b ...This particular Barracuda...
1b ...This particular Barracuda features some unique suspension modifications performed by team member Dave Christie that are not found on the earlier Super Stock Barracudas. At Chrysler’s direction, extra bars were added to the rear suspension (they remind us of Cal-Trac bars), and the lightweight Corning rear window was replaced by a heavier unit to aid in traction.
2 Although the 426 Hemi in...
2 Although the 426 Hemi in this ’68 appears to be period correct with the proper cross-ram intake and many Sox & Martin–specific pieces under the hood, it’s actually a Street Hemi and showed signs of wear and potential failure with leaks, noises, and low oil pressure. The only choice was to remove the engine to inspect and rebuild it.
3a Fitting a race Hemi in...
3a Fitting a race Hemi in an A-Body required some special components like an offset firewall adapter for the master cylinder...
3b ...We also had to remove...
3b ...We also had to remove the centerlink of the steering system since is passes through the Jake King–designed high-capacity oil pan.
4 After removing the valve...
4 After removing the valve covers, we noticed clear signs that coolant was getting into the oil. This problem can mean anything from a bad head gasket to cracked components, so we continued to investigate until we found the root cause of the problem.
5 Removing and disassembling...
5 Removing and disassembling the cylinder heads, we found cracks in both the water jackets and combustion chambers that would prevent us from reusing these heads. As these Hemis are over 40 years old, it’s common to find parts that are no longer serviceable. We’d have to locate a pair of rebuildable heads for this engine, and they must be factory cast-iron units for a period correct appearance.
6 While tearing down the...
6 While tearing down the short-block, we noticed several problems, including oversize cylinders, knurled piston skirts, and a spun main bearing, which was one of the causes of this engine’s low oil pressure. We’re actually surprised this engine ran as well as it did and had any oil pressure at all. A few more miles and it likely would have failed catastrophically.
7 Seeing paint flaking from...
7 Seeing paint flaking from the block at the lower edge of the water jacket, we investigated the area only to find a crack that had been poorly repaired by peening the edges and attempting to seal it with epoxy. Combined with the peening around the core plug area, this is a sure indication that the block saw sub-freezing temperatures, causing the water inside to expand and cause the cracks. This is a good example of why you should use coolant or drain your block in the winter months if your area of the world is prone to freezing temperatures.
8 With the parts of our Hemi...
8 With the parts of our Hemi on an improvised workbench, we realized that the only serviceable parts in this engine might be the connecting rods. This was definitely a setback.
9 Since locating the parts...
9 Since locating the parts for this build was going to take some time, we installed a serviceable street Hemi in the car so it would at least move under its own power while we built the race Hemi. Because of the importance of a period correct look, we chose not to use aftermarket heads or block, instead searching for the proper factory components.
10 Through the help of some...
10 Through the help of some industry contacts, we were fortunate to find a serviceable block with a 1968 casting date. Additionally, after inspecting and pressure testing three sets of cylinder heads, we had a pair of factory castings we could use for this build. After taking the necessary parts over to Auto Performance Engines to be machined, we got busy ordering the rest of the components for this build.
11 Though finding the cracked...
11 Though finding the cracked block and heads and unserviceable crankshaft did set us back, we’re looking forward to filling our new block with parts from Comp Cams, Scat, Keith Black, and Indy Cylinder Head. Be sure to follow this project as we’ll assemble and install the race Hemi in this classic piece of Mopar History.
Summit Racing Equipment
PO Box 909
Indy Cylinder Head
8621 Southeastern Ave
Auto Performance Engines
1479 Berkley Rd.
3406 Democrat Road
2250 Agate Court