Power Parts

To feed the newfound cubes in his one-off 361, Buck wasn't shy about adding airflow capacity. The Edelbrock Victor heads come with large raised ports, which Clark reworked and fully ported to a variation of the famous Mopar Max Wedge port. A limitation on the port configuration was the requirement to run a two-plane intake manifold to compete in the 2012 AMSOIL Engine Masters Challenge. Buck opted for an Edelbrock Performer RPM manifold, since there is no available two-plane Max Wedge intake for the low-deck Mopar. The complication here is that the Max Wedge port window would be too tall to fit within the fingerprint of a standard port intake.

Buck solved the manifold puzzle by raising and widening the port while filling the port floor, essentially making a short, wide port that could be duplicated at the manifold. To mate the intake to the raised-port location, Buck fabricated manifold spacers out of oak plywood. The Victor heads feature Edelbrock valves, with generous sizing at 2.25-/1.81-inch diameter, admittedly crowded in the small bore of the modified 361. Buck tells us, "You have to be really careful with the small bore and the big-valve heads. We notched the bores, helping clearance and airflow, and checked the fit very closely." A Holley 1,000-cfm HP-series carb tops it all to provide the mix.

To work those big valves in the Edelbrock heads, Buck went with a COMP Cams solid flat tappet. With Mopar's large .904-inch tappet diameter, a very fast rate of lift can be designed into the cam profile. As Buck tells us, "These Mopar flat tappets are very fast, and perform just about like a roller. I went with a set of Harland Sharp rockers, using a 1.7:1 ratio on the intake, and 1.65:1 on the exhaust. I've been using the Harland Sharps for years, and they never give me any trouble. I did turn a set in to rebuild, and when they saw the rockers they told me they must have been built over 20 years ago, and they actually did them for me for free. The cam and rocker give me .656-inch lift on the intake and .642 on the exhaust, with the duration at 255 degrees intake and 259 on the exhaust [at .050]. I had some used NASCAR springs in the shop that I put on and they worked out really good."

Dyno Time

With the unusual Mopar's internals assembled, the engine was completed for testing with a set of Schoenfeld 1⅞- to 2-inch headers and a MSD ignition system. Testing at Hinkle Performance showed numbers that were very encouraging, topping the 600 hp level with ease. Buck relates, "We did run the engine with a single-plane intake manifold, and that was quite a bit better as far as top end power. The two-plane did make a lot more torque down low and into the midrange." Looking at the numbers it's hard to reconcile that the basis here is an old Chrysler 361. Topping out with a torque reading of 520 lb-ft, and delivering 618 hp at 7,000 rpm, this Mopar oddity proves that innovative thinking and a mastery of machining talent can pull unexpected power from an unlikely source. Really, isn't that what hot rodding is all about?

By The Numbers
412 Mopar Big-Block
Bore: 4.185 inches
Stroke: 3.740 inches
Displacement 412 ci
Compression ratio: 10.4:1
Camshaft: custom COMP Cams solid flat-tappet
Valve lift: .656/.642 inch
Rocker and ratio: Harland Sharp 1.7/1.65:1
Piston rings: BRC 1.1/1.1/3mm
Piston: BRC forged
Block: OEM production Mopar 361
Crankshaft: stock forged
Rods: Eagle 6.657 inches
Cylinder head: Edelbrock Victor
Intake valve diameter: 2.25 inches
Exhaust valve diameter: 1.81 inches
Intake manifold: Edelbrock RPM
Carb: Holley 1,000 HP
Header: Schoenfeld 1⅞ to 2-inch step
Ignition: MSD
Damper: PRW
Oil AMSOIL 10w-30
Fuel VP-100 Unleaded

On the Dyno
412ci Mopar
RPM TQ HP
2,500 420 200
2,800 443 236
3,100 452 267
3,300 469 297
3,600 483 331
3,900 489 363
4,200 492 394
4,500 513 439
4,800 515 474
5,100 520 506
5,300 517 522
5,600 510 544
5,900 508 571
6,200 496 585
6,500 491 609
7,000 465 618

SOURCE
Hinkle Performance
6358 E. Laurel Rd.
London
KY  40741
606-864-6897