614-hp De-Stroked 409-in HEMI Saved from the Pile!

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614-hp De-Stroked 409-in HEMI Saved from the Pile!

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Gen II Hemi - Salvage Value
http://www.hotrod.com/how-to/engine/150 ... age-value/
Vintage iron Gen II Hemi engines are one of the most coveted engines in the muscle car universe. The legendary status of this maximum muscle engine is not debatable, and between their value for restorations and power producing ability, you are going to expect to pay up for a genuine 426 Hemi block. In the case of this unusual Hemi combination, Buck Hinkle of Hinkle Performance Engines was able to put together a stout Street Hemi combination by seeing the potential of parts that others would have called junk. The Hemi block, in fact, was pulled from a scrap pile where it had been long discarded.

As Buck tells us, "I knew the guy who had the block, and it was actually a junk block that started this project. I had some of the parts to build it with, and I hadn't built one of these engines in 20 years—I just wanted to do it. A friend of mine bought the car this block came in new back in the '60s; It was a drag race car. He had aluminum rods and eventually they let go and went through the block. He blew it up years ago, and I got it out of the junk pile. It had the sides knocked out of it, but it was an original block and it was fixable. I didn't want to see a Hemi block junked that could be fixed."

Bottom End Reconstruction

Buck explained the block's repairs: "I got the block and put eight sleeves in it, and welded up the sides. In fact, I got a 383 block and cut it up for some pieces and welded it back together. If you look at it you can hardly tell where the repair was done. Another problem was that one of the main caps was missing. The Hemi engines have cross-bolted mains, so they are unique to those engines. I tried to find an original cap, but nobody seemed to have one. On some of our wedge engines we modify the mains by flat milling the cap and adding a cross-bolted cap support. I just made that style of cap for the missing one and then line-bored the block to true up the mains."

With the block suitably repaired, Hinkle had the basis for his Hemi build, which took an odd turn in relation to the crank. Buck explains, "I picked up the crank a long time ago from Ray Nickleson's place, where they had the Chrysler factory racing team. When Ray got rid of all that stuff he had an auction, and I got one of the cranks they used in the 404-cid Hemi. They found that the 404ci Hemi would put out almost the same horsepower as the 426, but turned more rpm. NASCAR and USAC were running a factor of 9 pounds per cubic inch, so with the factor, by running the de-stroked 404 engine you could take about 200 pounds off the car. On the short tracks and dirt tracks, the 404 with that weight off the car would just run better than the 426, but on the bigger tracks they would run 426 because the weight wouldn't hurt them there. The crank was messed up when I got it, and I ground it to a big-block Chevrolet journal size." With the ancient de-stroked race crank and a cleaned-up overbore of .040 inch, Hinkle's Hemi would have a displacement of 409 ci.

Filling the bottom end with the short-stroke combination required special considerations. Retaining the factory 6.860-inch rod length would mean that the already tall compression height of the pistons would grow by half the stroke decrease. To address this, Hinkle went with a longer connecting rod, "The rod is from Eagle at 7.100 inches long and is made for the 2.200-inch crankpin—so that matches my crank—and it also matches the wider Mopar width. The reason I used that rod was because with the short stroke you would end up with a big, long, and heavy piston. I went with the longest rod practical just to keep the weight out of the piston. I had JE make the piston for this combination, and they still needed a pretty good-sized dome. With the small cubic inches it takes a good-sized dome to get the compression ratio up where it is, but it is still less than 11:1."

Rounding out the short-block were fairly straightforward parts, including a Moroso oil pan and pickup holding the vital fluids. The windage tray is a Mopar piece, but it was modified by Hinkle by adding extra louvers to assist drain-back. The remainder of the oiling system is all stock, right down to the pump. At the front of the engine is a stock timing cover enclosing a Cloyes three-piece timing set, while a PRW aluminum water pump housing and mechanical pump circulate the coolant.

Powering It Up

With the essential Hemi bottom end put together, the focus was shifted to the parts needed to make power. Of course, the defining characteristics of the Hemi engine are those wide Hemi heads. Here, Buck started with a set of Mopar Performance aluminum replacement castings. Besides a huge weight advantage compared to the hefty iron stockers, the aluminum castings are much easier to modify.

Clark Hinkle handled the custom work here, which was extensive, as Clark detailed: "Right out of the box, we flowed the Mopar aluminum heads and found the intake flowed 296 cfm. The modifications centered on raising the ports within the constraints of the casting, and then continuing with detailed porting. I started by getting the top of the port up to where I wanted it, and then brought the floor up. Both the intake and exhaust ports were brought up, and then I welded the port floors and made it into a raised port head. The exhaust is now a ‘D' shape. We got the head flow up to 400 cfm on the intake, and in the 280s for exhaust. Valves are Ferrea, and measure 2.240 inches, intake, and 1.940 inches, exhaust. The stock Hemi intake valves are 2.250 inches, but the heads are going to run in a racing class that limits the intake valve size to 2.240 inches, so we cut the valve down to this spec."

To work with the high-flowing cylinder heads, a single-plane, single four-barrel manifold is the most practical choice, but the selection is limited for the Chrysler Hemi. Hinkle went with an Indy single-plane, but admits this manifold is mismatched for his application, "The manifold really is not right for what I was doing, since it is made for 572 ci and is for 5,000 rpm and up. It was the only choice we had for this application, so I got it anyway. It is really big inside, so we added epoxy to it to make it smaller internally to make it more appropriate for our small-displacement street combination. Indy makes the manifold to fit their raised-port head, and we found it lined up and fit our modified port position perfectly with a 1/8-inch gasket. This is a 4500 Dominator manifold, so I used an open adapter to the smaller 4150 bolt pattern."

Topping the manifold is a Holley 1000 HP 4150 carb. Hinkle relates that the carb functioned very well without custom tricks or modifications, "The carb was run straight out of the box. All we did was the basic tuning, working with the jets and air bleeds; basically it is just the way it comes from Holley." The big Holley carb and high-flowing heads and manifold combination all ensured the airflow capacity was there to make plenty of power from the small displacement Hemi.

The final part of the power puzzle was configuring a cam and valvetrain to complement the rest of the combination. With street duty in mind, a hydraulic roller was the type of cam selected, both for the power potential and reliability. The custom COMP grind features a moderate 246/252 degrees duration at .050, but works with high-ratio T&D rockers to achieve a massive .722-/.685-inch lift. The rocker arrangement features individual rocker shafts, which mount on a bedplate that bolts to the standard Hemi head. With a ratio of 1.7/1.65 and rock solid stability, this rocker setup is a welcome upgrade when running very high lift. The T&D rockers are lubed by a spray bar that runs up the middle along the rocker support bracket and the rocker adjusters are hollow to direct splash oil down to the pushrods.

With the radically quick valve action generated by the cam and rocker combination, the valves are controlled by a set of COMP Cams springs featuring 240/560 pounds closed and open load. Also, aiding stability and playing a key role in making this level of lift viable in a hydraulic roller application are the limited-travel hydraulic roller lifters, again from COMP Cams. The limited-travel lifters greatly reduce the plunger travel in a hydraulic lifter, reducing the potential for lifter related instability, making them function more closely to a solid lifter. A custom set of 3/8-inch Smith Brothers pushrods were the final player in the valvetrain combination, and here Hinkle tells us he would have gone even bigger if the clearance would have allowed: "I couldn't go very big on the pushrods because I had problem with the pushrods hitting the block and heads. The rockers seem to have a little bit different offset that put the pushrod a bit closer to the block. I had to do some grinding to the heads and the block to get the pushrods to work, so if I went to a bigger pushrod, I would have had a problem."

To The Dyno

The engine was dressed with a vintage set of Mopar Performance cast aluminum valve covers and completed with Hooker headers and a full MSD ignition system in preparation for dyno testing. Hooked to the DTS/SuperFlow dyno at the University of Northwestern Ohio, the proud Hemi had clearly come a long way from its scrap pile origins. As the hammer dropped, torque built steadily to a peak of 519 lb-ft at 5,300 rpm. Clearly, from the high torque peak this de-stroked Hemi combination liked to rev. Peak power of 614 hp came in at the top of our test rpm limit of 6,500 rpm, with output still climbing. Buck Hinkle and the crew at Hinkle Performance Engines proved that old Hemis need not die, even when most would consider them dead. Crafty engineering and old-time know-how was enough to let this Hemi live again.

Fast Facts

409CI Gen II Hemi
Bore: 4.290 inches
Stroke: 3.535 inches
Displacement: 409 ci
Compression ratio: 10.8:1
Camshaft: custom COMP hydraulic roller
Valve lift: .722/.685 inch
Duration at .050-inch lift: 246/252 degrees
Lobe separation: 110 degrees
Installed centerline: 106 degrees, intake
Rocker and ratio: T&D 1.7/1.65:1
Piston rings: Total Seal 1.2/1.2/3mm
Piston: JE forged custom
Block: 1966 casting, factory Hemi
Crankshaft: Kellog
Bearings: MAHLE Clevite
Rods: Eagle, 7.100 inches
Cylinder head: Mopar 2531110 casting, Aluminum
Intake valve diameter: 2.240 inches
Exhaust valve diameter: 1.94 inches
Intake manifold: Indy single-plane
Carburetor: Holley 1000 HP
Ignition: MSD
Header: Hooker, 2 inches
Damper: Pro Race
Oil Pan: Moroso
Fuel: VP 101 unleaded
Oil: AMSOIL 20w50 synthetic

On The Dyno

409CI DE-Stroked 426 Hemi
RPM: TQ: HP:
3,000 407 232
3,100 411 243
3,200 418 255
3,300 424 267
3,400 428 277
3,500 434 289
3,600 439 301
3,700 445 314
3,800 449 325
3,900 452 336
4,000 455 347
4,100 459 358
4,200 459 367
4,300 458 375
4,400 464 388
4,500 473 405
4,600 481 421
4,700 488 436
4,800 495 453
4,900 504 471
5,000 511 487
5,100 517 502
5,200 518 512
5,300 519 524
5,400 519 533
5,500 517 542
5,600 517 551
5,700 514 558
5,800 511 564
5,900 509 572
6,000 507 579
6,100 502 583
6,200 501 591
6,300 499 599
6,400 497 605
6,500 496 614

On the dyno at the University of Northwestern Ohio for the AMSOIL Engine Masters Challenge, the 409-cube Hemi had a chance to display its potential, delivering 519 lb-ft of torque, while the power recorded showed 614, and rapidly rising at the limit of the test rpm range of 6,500 rpm.
This is an interesting story on a cool Gen 2 HEMI build.
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