As he was preparing for the 2007 Popular Hot Rodding Engine Masters Challenge, veteran competitor Adney Brown had another challenge when deciding what engine to use. The task was to create an entry for the pump-gas competition that has become the showcase for forward-thinking, yet repeatable, engine combinations. With a 10.5:1 compression ratio limit, 91-octane pump gas, and a mandatory flat-tappet cam, Adney had to find an engine with a good basic foundation to build from. He chose a Mopar 318 engine with a mix of old and new technology. His decision was based in part on the design benefits inherent in the engine. Adney also candidly admitted he thought no one else would build a 318. High-tech and common sense together appeared to be a good combination, as his little 323-cubic-inch engine pounded out 427 foot pounds of torque and 477 horsepower! Big-block numbers from the smallest of small-blocks.
The how's and why's of this engine buildup might not be seen upon a cursory glance. Take a few minutes to sort the wheat from the chaff, the little details start to shine through, and it becomes easier to ask, "Why not build a 318? How could it not make power?"
First, a quick history of the engine in question. At some point as the sun was setting on the 1950s, and America's appetite was growing beyond what the postwar automotive industry was offering, it was clear to the staff at Chrysler that along with the new styling cues of the coming era, a new powerplant would be required-one that was lighter, more powerful, and could take advantage of growing trends in technology. When dawn rose on the 1960s, the engineering team from mother Mopar had completely redesigned the old 318 Polysphere engine into what it referred to as the LA engine. Although sharing several pieces with its predecessor, such as the crank, bearings, connecting rods, and harmonic damper, the new LA engine used a smaller bore, wedge heads, and lighter-weight castings (the "L" in LA stands for lightweight). This resulted in an engine that packaged easily into the smaller cars like Valiants, Darts, and Barracudas, symbolizing Chrysler's entry into the burgeoning high-performance ponycar market. With factory designed full-floating pistons, 18-degree valve angle cylinder heads, large-bore mechanical flat-tappet lifters, and a forged crank, the first LA engine measured up at 273 cubic inches, and appeared to be a perfect platform for some real power upgrades.
The first glimpse into the engine reveals a lifter valley baffle to keep hot oil from spla
After receiving the news that he was one of the lucky few invited to participate in the Challenge, Adney and his teammates, Mike Ridings and Randy Malik, picked up a later-model 318 "roller" block as their base, and began their exercise with the usual stuff-torque plate, hone the block, deck it for tight quench, and build sheetmetal block-off plates to keep from draining top-end and camshaft oil onto the crank and creating windage problems. What? Your small-block doesn't have those? OK, maybe that shouldn't be categorized in the "usual" column, but that is just one of the little details that allowed this little engine to make big power.
Adney owns and operates Performance Crankshaft in Roseville, Michigan, not far from Ground Zero of the automotive world: Detroit. Being a crankshaft guy, Adney knows the good and bad of OEM and aftermarket offerings, and chose to use a factory 340 forged crank for this build. The 273, 318, and 340 cranks all shared the same basic dimensions-stroke, rod journal, and main journal size-and he could have used any of them to get his final 323 cubic inches. The 318, and later-model 340 cranks, were cast iron, limiting their use in the high-performance arena, but the '68-72 340 engines use beautiful forged cranks with lightening holes, and Adney had access to a perfect donor. He explained some of his modifications: "It was a 340 crank we lightened up ... bullet-nosed the leading edges, and knifed the trailing edges." This aerodynamic modification allowed the crank to spin through the crankcase with much less resistance, reducing parasitic power losses.
"We took a lot of weight off the throw side," says Adney. "The more weight you take off the throw side, the more you can take off the counterweight side. I guess it probably ended up about 5 pounds lighter than when we started." Often, lightening the rotating and reciprocating weights might not show up on the dyno, but it will be worth its weight in gold at the track.
Even with a small dome, the pistons ended with an effective zero cc's of volume when figur
Some more effort into lightening the assembly is seen in the connecting rods. According to Adney, they used a 6.200-inch small-block Chevy rod, an I-beam design from Scat. The small-block Chevy and Mopar rods are very similar, with the Chevy rods just slightly smaller and wider in journal size. With the tools at his disposal, Adney just widened the throws on the rod journals to fit the Chevy rods, and he was able to take advantage of the smaller wrist pin and extra length provided by the budget-priced rods. For a re-creation of this engine, Adney suggested, "the Mopar rod is really totally sufficient for street use. You can bush it for a smaller pin, or even stick with the Chrysler pin and use a thinner wall. I mean, 6.125 inches is nothing to sneeze at," referring to the stock length of the Mopar rods.
At the small end of the rods swings a set of custom Diamond pistons with a lightweight Speed Pro ring pack. "We ran a low-tension oil ring, which we did modify the expander on, crimping it. That lowered the tension on it. We ended up with about an 8-pound pull." Ring tensions that low build great power, but Adney admitted they had a tough time getting the rings to seat during testing. By the time they brought their powerplant to the Challenge, there was no blow-by present.
When asked about engine coatings, Adney states that he is a believer. "The first year I was in it, which was in 2003, I coated everything but the rods. I did the intake, the ports, both sides of the head, everything. And you know that's a ton of work. We've never done any testing before and after, so I can't really tell you, but even if it only gains you four or five points, it's worth it." This year, he and his cronies at Performance Crankshaft did the coatings themselves, using different applications from Tech Line Coatings. Instead of coating everything they came across, however, they concentrated on what they considered key areas, specifically the tops and skirts of the pistons.
Considerable attention was paid to the stock Mopar crank. After reshaping the throws and c
The oiling system on Adney's 318 block received treatment that should be standard operating procedure on any performance-oriented LA buildup. Problems start at the oil pump pickup tube. As it comes from the factory, the oil pumps are designed for a 3/8-inch screw-in pickup tube. That might be adequate for grandma's grocery-getter, but not for an engine making big power and turning a bunch of rpm. One might think the first response is to bolt on a high-volume pump, but in the 1970s, Chrysler engineers tested the flow volume with standard- and high-volume pumps, and found almost no flow difference until a second pickup tube was added to the bottom plate of the pump. Adney's version of this was to block off the stock oil inlet in the pump, and build his own pickup, threading it directly into the bottom pump plate. "I drilled straight through the oil pump cover, and I just plugged the normal place where the pickup would go in."
On older blocks with a ton of mileage, worn-out lifter bores can be a major source of oil pressure loss, as the passage that feeds the main bearings partially intersects eight of the lifter bores. The block that Performance Crankshaft was working on was in good shape here, but there are two options for those not as fortunate. The first and easiest is to "tube" the block. That is, drill and ream out the oil galleys that intersect the lifter bores, install a copper tube down the galley, run a broach down the lifter bores so the copper tube doesn't affect lifter operation, then re-drill the oil passages going to the main bearings. The tools and tubes necessary for this are available from Mopar Performance. The second option to fix the aforementioned problem is to have a machine shop install lifter bushings in the block. Although significantly more expensive, it is the recommended procedure for a race engine, especially for flat-tappet cammed engines, as the fixturing locates the lifter more precisely and accurately than the OEM tooling. As mentioned above, Adney's block was in good enough shape that just using an out-of-the-box Melling pump with the modified pickup provided a solid 55-60 psi from the hit all the way up to 6,500 rpm.
Something to consider if you plan on slapping together a combo like this is the fact that earlier non-Magnum blocks ('64-92 model years) send oil to the heads differently than the Magnum engines. The early blocks, like the one we're dealing with, shoot oil from the No. 2 and No. 4 cam bearings through holes in the cam, up through a passage in the block and the head, ending up at the rocker shaft where it is distributed to each of the rocker arms. The Magnum blocks and heads are not drilled with that passage, as they get oil through the lifters, then up through the pushrods like Chevy and Ford engines. When using Magnum heads on early blocks, the easy way to get oil up top is to use AMC lifters (which are dimensionally the same) but with pushrod oiling provisions, and use hollow pushrods like the pieces from Trend that Adney has. When setting up an engine this way, you can block the unused oil passages by either clocking the cam bearings so the holes don't line up with the passages, tapping the block passage in the deck, and installing a 5/16-18 setscrew in it, or simply using the Magnum head gasket that doesn't have the oil holes.
Adney plugged the original 3/8-inch NPT entry to his Melling oil pump, then built his own
Moving up higher on the engine, Adney used a set of Mopar Performance R/T Magnum cylinder heads, sourced from friend Randy Malik, owner of RM Competition. Randy "knew a guy who knew a guy," so they ended up with a set of former Super Stock heads that were in great shape. When asked about modifications, Adney responded: "They were ported when we got them; we just touched them up a little bit." Apparently, they were ported pretty well. (If we were to duplicate this buildup, we'd reach for a set of Engine Quest's iron Magnum heads, which will get you in the ballpark with minimal machinework and porting.) LS1-style Chevy valves were installed, along with a set of COMP Cams beehive springs and retainers. The combination worked great, as there were no signs of valvetrain instability with the tach climbing to 6,500.
The brain of the engine was a COMP solid flat-tappet camshaft with 247/247 degrees of duration at .050-inch lift. A mix of Harland Sharp and Crane rocker arms (1.7 intake and 1.6 exhaust, respectively) brought the lift to an impressive .622/.597 inches. The R/T Magnum heads were designed as basically an upgrade to the later-style Magnum heads, and the nonadjustable pedestal mount rockers wouldn't cut it with an aggressive solid lifter cam. A Crane rocker stud adapter kit was used that also incorporates a set of built-in pushrod guideplates. The kit goes a long way toward improving the valvetrain on the R/T heads, but with the 5/16-18 threaded holes that the studs live in, there is not a whole lot of stability there. Being a machinist, Adney solved this dilemma by making his own stud girdle.
The engine uses a Professional Products dual-plane intake sandwiching Fel-Pro Performance intake gaskets. Regarding the use of an early-style gasket on the late-model heads, Adney set the record straight: "They say the Magnum heads are supposed to use a different gasket from the regular heads. I found out that the regular gaskets, the 1243 Fel-Pro's, work just fine. The only thing you have to do is slot the boltholes. It works better than any other gasket they've got." The slotting is necessary due to the fact that the Magnum intake boltholes go straight up and down, whereas the early-style holes are perpendicular to the intake manifold face.
The R/T Magnum has an already efficient combustion chamber that was cleaned up during port
Topping the engine is a Holley 950 HP and a pair of Jomar carb spacers. "The carburetor was done by Randy Malik. Randy's about the best carb guy I've ever met." It was apparent that he knew what he was doing, as the fuel curve was nice and flat.
On the periphery, MSD provided the spark with a venerable 6AL firing the Champion Racing plugs. A set of Hooker headers bolted to Magnaflow mufflers kept the exhaust moving at a steady clip after exiting the combustion chamber. The power created by the Shell V-Power 91 octane passed through a Hays flywheel before ending up at the DTS dyno.
After the dust had settled and the Challenge had ended, Adney reflected, "318s don't have a very good following or a very good name." Like the Rodney Dangerfield of the performance world, the 318 gets no respect. The LA engine was in production for 39 years with variants ranging from the baby 273, to the 360s, and several in between. Of all the Mopar small-blocks created, the 318s were always referred to as the wheezing, slowpoke, economy engines, but Adney Brown truly believes that even on a modest budget, that little engine can be made into a stout performer. And the dyno-the great lie detector-agrees!
Milodon provided the oil pan and windage tray for the 318. Similar to early Chevy II's, th
With the super-aggressive COMP Cams MM and MHF solid-lifter cam lobes designed for the big
The 318 has LS1-style lightweight Ferrea valves. The COMP beehive springs are set up with
Fel-Pro doesn't currently offer a performance intake gasket for the Magnum heads; however,
With the small cubes, a small, dual-plane intake ended up making the average torque and ho
This innocent-looking carb started life as a generic Holley 950 HP, then was modified by R
Combining a two-hole with a four-hole spacer effectively increases plenum volume while ret
Bombproof as ever, an MSD Pro Billet distributor backed by a 6AL box and MSD plug wires pr
Displaying their ingenuity once again, Adney and the crew from Performance Crankshaft came
Adney Brown has reason to smile. In addition to his own entry into the 2007 Jegs Engine Ma
|BY THE NUMBERS |
|323CI SMALL-BLOCK MOPAR |
|Bore: ||3.936-inch |
|Stroke: ||3.315-inch |
|Displacement: ||323 cubic inches |
|Compression ratio: ||10.44:1 |
|Camshaft: ||COMP solid flat-tappet |
|Cam duration: ||247/247 degrees |
at .050-inch tappet rise
|Valve lift: ||.622-/.597-inch |
|Rocker ratio: ||Harland Sharp 1.7:1 intake; |
Crane 1.6:1 exhaust
|Lobe separation: ||105 degrees |
|Intake centerline: ||99 degrees |
|Top ring: ||.043-inch Speed Pro barrel face |
|Top ring gap: ||.018-inch |
|Second ring: ||.063 Speed Pro, scraper |
|Second ring gap: ||.018-inch |
|Oil ring: ||.187-inch |
|Piston: ||Diamond dome, |
zero cc effective volume
|Block: ||OEM roller 318 |
|Crankshaft: ||OEM forged 340 |
|Rods: ||Scat SBC 6.200-inch I-beam |
|Main journal: ||2.490-inch |
|Main bearing clearance: ||.0022-inch |
|Rod Journal: ||2.100 inch |
|Rod bearing clearance: ||.0022-inch |
|Cylinder head: ||Mopar Performance |
|Intake valve diameter: ||2.020-inch |
|Exhaust valve diameter: ||1.600-inch |
|Intake manifold: ||Professional Products |
| ||dual-plane |
|Carburetor: ||RM Competition modified |
Holley 950 HP
|Header: ||Hooker 1-5/8-inch primaries |
|Ignition: ||MSD 6AL |
|Damper: ||Professional Products |
|Water pump: ||Professional Products |
On The Dyno DTS Dyno Data
Performance Crankshaft 323CI Small-Block Mopar
|RPM ||TQ ||HP |
|2,500 ||337 ||161 |
|2,600 ||350 ||173 |
|2,700 ||357 ||183 |
|2,800 ||357 ||190 |
|2,900 ||356 ||196 |
|3,000 ||351 ||201 |
|3,100 ||345 ||204 |
|3,200 ||339 ||207 |
|3,300 ||343 ||216 |
|3,400 ||356 ||230 |
|3,500 ||371 ||247 |
|3,600 ||385 ||264 |
|3,700 ||396 ||279 |
|3,800 ||404 ||292 |
|3,900 ||410 ||305 |
|4,000 ||415 ||316 |
|4,100 ||418 ||327 |
|4,200 ||420 ||336 |
|4,300 ||422 ||345 |
|4,400 ||421 ||353 |
|4,500 ||420 ||360 |
|4,600 ||421 ||369 |
|4,700 ||425 ||380 |
|4,800 ||426 ||390 |
|4,900 ||427 ||398 |
|5,000 ||427 ||407 |
|5,100 ||427 ||414 |
|5,200 ||426 ||421 |
|5,300 ||425 ||428 |
|5,400 ||423 ||435 |
|5,500 ||421 ||440 |
|5,600 ||419 ||446 |
|5,700 ||417 ||453 |
|5,800 ||415 ||458 |
|5,900 ||412 ||462 |
|6,000 ||407 ||465 |
|6,100 ||401 ||466 |
|6,200 ||397 ||469 |
|6,300 ||393 ||471 |
|6,400 ||390 ||475 |
|6,500 ||386 ||477 |