The Chrysler 426 Hemi Is a 50-Year-Old Engine. Why Are We Still Talking About It Today?
“So do you think the Hemi is overrated?”
I’m sitting at a small table at the Waffle House in Ocala, Florida, when I ask this question, and “Big Daddy” Don Garlits nearly slams his fist in his scrambled eggs and tomatoes as he leans across to answer me. “No,” he shouts, waving a triangle of toast. “It deserves every bit of its reputation.”
Well, Don Garlits would know. The Chrysler Hemi helped him achieve 17 world titles, eight U.S. National championships, and more records and event wins than we could list in this magazine, let alone this article. I offer him some of my waffle to make up for asking such a stupid question.
Later, during a phone interview, I ask the same question to Ramcharger and former Chrysler engineer Tom Hoover. His irritation is palpable through the speaker. “Oh, gee whiz,” he says. “The basic engine has been active for 50 years. You have to be pretty proud of that.”
You either want one, or you want to beat one. The 426 Hemi is a myth-making monster of motorsports. It certainly looks the part of super engine, immediately recognizable in an engine bay with its fearsome, wide valve covers and center-mounted spark plugs. When it fires up, it sounds like the drumroll to the apocalypse. As Hoover pointed out, Chrysler’s 426 Hemi has been around for 50 years, and if anything, its reputation is even more ferocious than when it was born. How does a passenger-car V8 get that kind of notoriety, and who was responsible for the success of the 426?
It’s Pontiac’s fault, really. In the early ’60s, Pontiac-powered cars were winning races on the track and on the streets, and teenagers in Detroit went home at night and told their dads about the cars they saw. You can imagine this was pretty infuriating when the dad in question happened to be Lynn Townsend, CEO of Chrysler. Townsend stormed into the engineering department and demanded an engine that would win circle-track and straight-line racing along with the hearts of car nuts ever after. At least, that’s how the legend goes. What we know for sure is that this edict for race domination led to the 426 Hemi, which was on the NASCAR podium just a year after draftsman Frank Bialk began the engineering drawings.
In December 1962, Manager of Engine Design Bill Weertman and a small group of Chrysler engineers, dyno operators, draftsmen, and technicians got word of a new assignment — to get an engine ready before the ’64 Daytona 500—and while they were at it, to develop a version for drag racing as well. Tom Hoover was a part of this team, already deeply involved with the Max Wedge engines and the Ramchargers’ racing effort. When the brass came down and asked what it would take to win the Daytona 500, Hoover, Weertman, and the team didn’t even consider trying to use the 426 Wedge engine. “It was dominating in stock classes at the drags,” Hoover explains, “but really, it was just a street-car motor. We suggested putting the Hemi head on the wedge block. It wasn’t radical; it was just the best way to take advantage of work that had already been done. There was all this R&D that had been done on Hemis for the 331-based A311 Indy program back in the ’50s.”
It took until the spring of 1963 before official approval for the 426 Hemi came through, but by then, Weertman and Frank Bialk already had engineering drawings to discuss.
“Bill and I, we had an inkling that the upper management wanted to win Daytona, so we were already working on it,” Hoover says. They had just less than a year before the engine had to be not only running but also winning.
Designing the 426 Hemi wasn’t as simple as just scaling up the 392 Hemi. The goal was to use the basic block design of the RB wedge, which had superior bottom-end strength, due to a deep-skirt block. Much of the head design came from the earlier Hemi research, but this caused some complications. The point of the engine was power, so all efforts were made to maximize intake and exhaust flow and allow for high-rpm performance. Hoover recalls numerous rocker-arm designs as the engineers tried to find a way to angle the valves that didn’t call for an unfeasibly long rocker arm length. The final decision was to tilt the heads inboard, which also solved a problem of the pushrods being too close to the sealing bead on the head gaskets. Another major difference between the first- and second-generation Hemi engines is that the 392 used a four-bolt-per-cylinder head-bolt pattern. The 426 called for five, but then the inside bolt ended up in the path of the intake port. Eventually, this bolt was moved to thread in from below, through a boss in the tappet area of the block. The fact that Chrysler was willing to make expensive and time-consuming engineering and assembly concessions to the Hemi shows how serious the quest for power and a race-winning engine really was.
The Hemi project wasn’t a secret. Garlits recalls being told by Dodge P.R. man Frank Wylie that he should be expecting a Hemi-headed wedge engine by the end of 1963. “Sure enough,” he says, “it showed up. I didn’t like its looks. That internal [underside] bolt, I hated that! You know, the 392, 10 bolts, you could take that apart easy. We weren’t excited to use the 426 [Hemi]. We weren’t sure how committed Dodge was going to be to this new engine.”
As it turns out, Big Daddy was right to be cautious. Although initial dyno pulls on the Hemi in early December 1963 showed big horsepower numbers, 530 horses, later 550 and more — this when the very best race-prepped Max Wedge powerplants put out about 490 — it didn’t take long before the massive power and massive parts in the 426 caused massive failures. One of the first mechanical issues in the 426 was due to the heat that would build up in the big domed piston. This caused wristpin failures when the hot piston expanded around the pin bore until the assembly came apart. No sooner had the engineers redesigned the piston pin locks then another more serious problem cropped up.
The guys were running the 426 through the Daytona 500 simulation on the dyno, but the engines weren’t making it through the test. Each one would crack the cylinder bores before the time allotted for the race. Bill Weertman recalls the day the problem was discovered with a typical engineer’s cool demeanor. “Larry Adams [the dyno operator] came in and he didn’t look very well. He said, ‘Bill, we’re not gonna finish the race,’ and I said, ‘Oh, that’s nice.’” They had less than two months before Daytona.
Post-mortem work on the failed engines showed that the cracks were forming in the same place on all the engines. Weertman headed to the Chrysler foundry in Indiana to see what could be done to cast blocks with thicker walls. Engine blocks were made through a multipart process involving cores made of casting sand. There wasn’t time to start over completely, but there was hope that the existing cores could be modified in the fragile area for a thicker block. “We had to do our work after hours,” Weertman says. “We couldn’t interfere with the making of production engines. We made our first attempt, and they ladled the molten iron in. Then we had to wait until it cooled enough to handle. It must have been about one in the morning when we finally could look at it.”
The results were not good. It would be several sleepless nights before there were usable blocks. Those castings had to go on to be heat-treated and machined before they could be assembled, and all this time the race was getting closer, and no one knew for sure that the new blocks would be enough.
At the same time that Weertman was shaving sand castings in a frantic attempt to strengthen the block for Daytona, the drag-racing guys had their own problems. Hoover was in California preparing for the Pomona Winternationals. “We had some 426 Hemi cars there,” he says “But they were just stock engines, bolted together by the assembly line at the Chrysler marine facility in Marysville [Michigan]. We rented track time to make some test runs, and they were slower than the Wedge cars. We couldn’t have that at Pomona—our new race package be slower! We didn’t run them again till later, after I had taken them apart, blueprinted them, made some real headers, that kind of thing. Then they ran good.” That last sentence is another bit of engineer’s understatement. In the spring of 1964, The Ramchargers A/FX Dodge ran an 11.22 at 125.17 mph, claiming both ends of a new record.
So, by mid ’64, the Hemi had claimed stock car racing and was well on its way in naturally aspirated straight-line racing, but what about blown nitro, the place where it remains king to this very day? There, things were not going so well.
“Nobody wanted to switch from the 392,” Garlits says. “I was doing great with the 392, but Frank Wylie said, ‘We don’t make that engine anymore.’ He wanted me to race with something the customers could buy. There were a few of us running the 426. Me, Roland [Leong], The Greek [Chris Karamasines], and a lot of people had ’em, but it was like a second car. None of them ran good. We called it the ‘elephant;’ it was a brute! You never smashed the ring lands or squished bearings like in the 392, but it didn’t go anywhere. You know, like an elephant, so big and massive, you can’t hurt it, and it just sort of plods along.”
The elephant ambled through 1964 and 1965, winning a few races, but never winning over the racers themselves. By 1966, Garlits was tired of the pachyderm. He was darn near ready to quit racing the big motor altogether, and if he’d done that, I might never have sat in his wood-paneled office, while he waved a gun around and told me the following story.
“It all came to head for me at Columbus. I went in for a match race against the Lees, Jim and Alison Lee. It was a Saturday night. I ran three runs in the 8s [with the 426], the 392 ran in the 7s, easy, and [the 426] ran 191, 192 mph. The 392 was running 206, 210, easy. I won the race and had top time and low e.t., and I went up to the tower to get paid.”
Here he stops and looks at me, “Do you know what a .45 pistol is?”
I do not, so he goes behind his big desk, which is covered in trophies and photos and a framed letter from President George H. W. Bush, thanking Big Daddy for a signed poster and sending regards from Barbara. Garlits rummages in a drawer for a second and comes out with a large handgun. “Do you know why I like the .45?” he asks, “Because they don’t make a .46!” He laughs. Is there any wonder that a man like this, with a love for the biggest and best machinery would be one of the first people to discover the awesome power of a blown 426? But as he’ll tell you, it almost killed him.
“So I go up there to get paid,” he says, after putting away the .45, “and Clark Radar, Sr. [the track owner] is sitting there behind this big desk, like this one,” he gestured toward his own. “But not one thing on it except this stack of money and a .45 pistol, and overhead, this big moose that he’d shot. It was a very intimidating situation, the gun, Mr. Radar, and the moose. He says, ‘Garlits, you laid down on me. You didn’t run 200. I’m cutting your money.’ Then he shoved $500 dollars toward me with one hand, and kinda slid the gun toward me with the other, and told me to get out. Well, I did, but he cut me $750 and that was a lot of money back then.”
Garlits stops for a second so I can imagine his mindset as he left Columbus that night for another match race in Illinois the next day.
“I’d figured out what I was going to do,” he says. “I was going to run the 426, blow it up, load it up, and go back to the 392. Walk away from the Dodge sponsorship, the whole mess. So the next day I put 40 degrees spark lead in the thing — we couldn’t run more than 34 in the 392 or they’d split the cylinder walls. Everyone knew that, so we all ran the 426 the same. My crew was sure I was going to blow it up. They had the backup engine in the truck, ready to go. Well, I make the run, and what do you think it runs? 214 mph! A new world record. We get it back to the pits and drop the pan, expecting to see damage, and it looks beautiful, we didn’t even change the oil! So I get the wrench on the magneto to try more, and the crew is begging me not to, saying ‘Big, it’s a nice engine! It just ran a world record! Don’t blow it up!’ but I got to know, so I go for 50 degrees, and it runs 219. That was it, that was the end of the 392 for me.”
Soon other racers figured out the secret and by the end of the decade the 426 Hemi was ruling racetracks in almost every configuration. The engine’s race rep followed it to the street, and it took a brave soul to line up at a stoplight against anything with a Hemi badge on the hood. Today street Hemi cars command sky-high prices, and it continues to be the engine architecture of choice in contemporary Top Fuel and Funny Car racing, a fact Garlits puts down to it being “the best tool for the job,” and Bill Weertman describes as “very flattering.”
So, yes, Tom Hoover, you should be proud.
Over the last five decades, Chrysler has come up with a number of experimental 426 Hemi engine configurations. None of them ever made it into actual production, but it’s interesting to imagine what the performance landscape would look like if they had.
When Ford revealed in 1964 that it had built enough SOHC versions of its 427 OHV wedge V8 to qualify it for potential NASCAR service, Chrysler responded by making plans for the A925. This competition-oriented 32-valve version of the 426 Hemi, known to Bill Weertman as the “Doomsday Hemi,” was designed on paper in two different forms. Both approaches called for improved airflow and engine-speed capacity through the use of four valves in each combustion chamber. They were intended as virtual “bolt-on” enhancements for the already engineered and then-current 426 Race Hemi’s short-block, lube, and cooling systems. The challenge of stuffing more valves into existing real estate was overcome by some savvy valve sizing, and by closing up the 426’s 58.5-degree included angle between the rows of intake and exhaust valves.
The primary A925 multivalve plan called for a pair of camshafts, each carried in a row of cast-in capped saddles atop the head. Cam lobes acted directly on caps on the valve stems. Selectively sized caps determined valve lash. Drive was via a cog belt and compatible sprockets. Although a working A925 was never built, heads, cams, and related parts were manufactured, and an “engine” was assembled. It was seen in one well-publicized image that appeared to show a functional test engine — camshafts, drive gears, belts, and cam-cover studs exposed — on a dynamometer. Fact is, the assembly was a 426 Hemi DOHC evaluation fixture. Without pistons or rods, the mock-up’s crank and cam drive were spun by an electric motor for valvegear and camshaft analysis. But with a distributor, alternator, oil filter, and lube plumbing, it sure looked like an operable powerplant.
A second, more “conventional” 32-valve A925 was also drawn up, just in case NASCAR decided to ban overhead-cam engines from Grand National competition. This concept retained the Hemi’s traditional double-rocker-shafts, but its narrower head allowed shorter rocker arms to work the valves. The big departure in this sketchy backup scheme was a pair of side-by-side camshafts in twin block tunnels, each acting on 16 tappets and 32 total pushrods to cycle the overhead valves. This design never progressed beyond Frank Bialk’s drawing board, but it’s possible it was never intended for production.
Chrysler circuit racing manager, F.R. Householder, showed NASCAR officials a photo of the DOHC Hemi on a test stand and made it clear that the development project would continue if Ford’s cammer were deemed legal. All the while, Householder was hoping Chrysler teams would be allowed to continue campaigning the standard “production” 426 Hemi. NASCAR responded with a notion of its own — one that banned all overhead cam engines from its racetracks. And that, fast fans, flat ended the A925 program. Still, imagine how cool would it have been to see a field of 7.0L OHC Hemi Fords running fender-to-fender with DOHC Hemi Dodges and Plymouths on the high-banks at Daytona. The sound alone would have been well worth the price of admission
Back in 1968, efforts to improve both the production practicality and the overall mass of the 426 Hemi V8 led Chrysler to its more-than-experimental A279 — the now-legendary “Ball Stud Hemi.” We say “more than” because some of these V8s actually got built. A key facet of the project concerned the inspiration for the BSH motor’s unique-to-Highland Park rocker pivots. No, it had nothing to do with GM’s porcupine design or with Ford’s Boss arrangements but rather with a cylinder head study done for a Chrysler Australia inline-six. Among the configurations investigated for that (’70–’81) 245ci Down-Under Hemi was one calling for individual pedestals for each rocker-arm pivot. Applied to the A279, this simplified stud-based layout provided plenty of room for large Hemi-size canted valves and generously proportioned port contours. In addition, the combustion chamber configuration that resulted took a very Hemi-like form. In dyno tests back then, a 444ci BSH made more power than a production 440 RB wedge and less than a 426 Hemi. But once again, some of the same factors that finished the 426 after 1971 (emissions and vehicle insurance rates) also influenced the BSH’s aborted production plan.
The Hemi 99
Here’s a Hemi offshoot that is available, although somewhat controversial. Late last century, responding to the ever-escalating performance levels of heads-up, big-inch, V8 drag-race competition, Mopar Performance (MP) unleashed its latest “Hemi” motor on the Pro Stock racing world — the “Hemi 99.” As most “Mopurists” would probably agree, this model is very different from the ’64 426. Sure, the engine has wide valve covers boldly emblazoned with the word “HEMI.” But the cast-iron version of the 99 block, Mopar part number P4876887AB, is molded with an extra 1⁄10 inch of bore spacing (4.90 inches) to allow the overbores that yield the NHRA’s Pro Stock maximum displacement of 500 ci. It also has a considerably lower-than-OE 9.28-inch deck height and four more cross-bolts than a stocker. And though the aluminum 99 cylinder case (P5249533) retains the original motors’ 10.72-inch deck height, it’s cast with even more generous 5.00-inch bore centers. This casting is capable of the 800-plus cubic inches needed for the more liberal sanctioning bodies’ straightaway contests. MP’s catalog even refers to this alloy incarnation of the 99 as an “IHRA Mountain Motor Pro Stock block.”
Up top, 99s accept only “spread-bore” cylinder heads designed specifically for those blocks’ wider cylinder centers. Both types of available MP alloy castings (for NHRA and IHRA) retain the original 426’s equally spaced port layouts, but port contours are more round than rectangular for improved low- and mid-lift flow capabilities. The combustion chambers in the heads are configured nothing like a conventional Hemi. They’re lots more like the Oldsmobile DRCE’s “figure-eight” shape, only rotated (about the bore axis) maybe 70 degrees, to put the intake valves and ports inboard and the exhausts outboard, almost directly opposite the intakes. Displacing 47 cc, this shallow chamber layout offers superior mixture swirl potential, compared to a conventional cross-flow Hemi. And the lower domes that smaller chambers call for means the motor can use lighter pistons with compact crowns to promote more efficient flame front propagation than a traditional Hemi’s obstructive piston pop-ups do. And in another major departure from the original factory plan, the old OE Hemis’ familiar double shaft rocker system is nowhere to be found, replaced on 99s by individual pivot shafts that accept more modern full-roller (fulcrums and trunions) rocker arms. In 2006, a second generation of Hemi 99 blocks and heads offered a number of structural improvements, as did the compacted graphite iron blocks that followed. All of this widely available contemporary hardware carries genuine Chrysler/Mopar Performance factory part numbers. They’re what make these Hemi 99 engines legal for competition under all sanctioning body rules — despite the fact that nothing resembling the 99 has ever come anywhere near a production vehicle.
Get a 426 Hemi of Your Own
Race Hemi builder Ray Barton says the Gen III Hemi may not look as cool as the original 426, but it can do some pretty cool things. Try a new Mopar Performance crate 7.0L 426ci engine in your choice of 515, 565, or 615 hp. $18K will get you the six-hundy horse all-aluminum version. Mopar Performance part number P5156139.
If you’re sticking old-school, a Gen II 426 Hemi crate engine can be yours for a little over $16K. Try Mopar part number P5249667AE. If you like ’em a little bigger, MP offers strokers up to 572 ci.