1969 Road Runner Project, Part IV

The combination of a stock length, 6.760-inch Eagle rod; 600-gram Lunati custom relief piston; and 160-gram full-floating .990-inch diameter wrist pin makes up the remainder of the rotating assembly. The rods are retained by ARP bolts. For a street engine, this is much lighter than usual and probably assisted Indy in breaking the 500hp barrier and offered increased rev-ability.

The Lunati forged, 40cc reverse-dish piston offers the 542ci Indy engine ample combustion chamber size, despite a zero piston deck height and the 78cc chamber volumes of the Indy 440SR heads. This is important. In order to eliminate any chance of detonation with the moderate 9.5:1 compression ratio, the temperature throughout the chamber must be consistent. As a result, combustion occurs predictably across the piston surface. As bore diameters increase, this "squish effect" is harder to control, and when not considered, detonation is a likely result. The series of narrow grooves just below the piston surface are anti-detonation grooves. They also help reduce the chance of detonation as the grooves disperse raw fuel along the cylinder wall through piston travel rather than allowing it to reservoir along the ring and piston top surface. While on the topic of rings, the set is made up of 1/16, 1/16, and a 3/16 standard tension oil ring. The Holley Roadrunner will primarily be a street machine, yet we intend to do a little racing. We made it clear to Ken that we wanted both power and seal without the oil contamination that looser, high-horsepower race engines are known for.

The cylinder head for the 542ci Holley Roadrunner would be Indy's 440SR head. Using 906 castings as a baseline, the 440SR is Indy's first step in terms of a performance gain with its extensive line of Mopar-specific B/RB cylinder heads. Designated a street/strip head, the 440SR is the closest thing to a stock replacement that Indy offers. It doesn't require an offset rocker arm--any 906 style rocker will work, as will any intake manifold in the aftermarket.

According to Ken, "Our goal with this head in this application was to produce a peak intake airflow rate of 320cfm while maintaining intake port runner volume at a moderate 270ccs compared to a ported 906 head's volume of 190cc." As for flow balance, the exhaust port is 75 percent of the intake and deemed a high-velocity head, perfect for the moderate airflow goal we were interested in obtaining. "Will the 542 make the most horsepower with this head?" you ask. "No," according to Lazzeri. "This engine has far more potential--it is basically a detuned race engine specifically designed for a street machine. With a much larger port volume and greater airflow volume rates, the 542 could easily produce 800hp with a roller cam, high compression, and fully ported heads--maybe even with the 440SR head."

Ken is quick to note that Mopars have always been well known for torque. "Recognize that the 320cfm intake airflow rate for a 440 may have seemed large for a torque-only engine, but remember Chevrolet offered airflow rates of 270cfm right from the factory with 396 Chevrolets." As airflow goes up proportionately with port size, so does horsepower, as long as the engine can effectively pump the air available.

Sure, a race-compression 542ci engine could produce 800+ horsepower, but what we wanted was street reliability and torque. Opening the Lunati catalog to camshafts, Ken chose Lunati's hydraulic PN 33706. Technically, it has the look of an MP Purple Shaft cam with a generous 110-degree centerline. Specs are .507/.534-inch lift, intake and exhaust, respectively, with an advertised duration of 285-degrees on the intake and 295-degrees on the exhaust. Duration at .0500-inch lift is 235/245, intake and exhaust, respectively. Ken chose to install the cam 3-degrees advanced, reducing the centerline to 107-degrees. For those of you with 383s, 400s, and 440s who think this cam is a bit too aggressive, remember, our displacement is 542ci. Ken says, "With that kind of displacement, you don't even hear the cam at idle."

A Lunati 3-position cam chain and sprocket set is used as a Roller thrust button to reduce friction. Here, Ken readies the thrust button for installation with a liberal coating of lithium grease for startup and break-in. No oil is squirted to this location.

The overall simplicity of the top side of each cylinder head adds to the durability and reliability of our 542ci combination. The 1.5:1 Indy SR roller rocker was chosen here, but remember, any aftermarket adjustable rocker system will fit, including the stock 1.5:1 rockers.

For the ultimate in street performance, what else would you choose besides a dual-plane intake, Indy style? This manifold (PN 440-20) offers better throttle response than a similarly-sized single plane, but with the amply-sized runners, there are few single planes that actually displace more air for Chrysler B/RB engines. The efficiency of the dual-plane design assists to make the 542 a clean burning engine, even if it is a thirsty one. The throttle response is staggering and the wide power band from 1,500 to 6,000 rpm makes this the perfect manifold for big-inch Wedge engines. If you are looking for a universal B/RB manifold, this is it! It fits 906 castings as well!

To ride aboard the giant dual plane, a carburetor capable of 900+ cfm of airflow was necessary, but not of the racing variety. Ken Lazzeri swears by the Holley Pro Series List 4150, especially PN 80497. "The Pro Series vacuum secondary carb is super responsive," says Ken. "On a street car, you want controlled secondary response and that is what the vacuum secondary carb offers." However, if you needed large cfm air/fuel flow, you were out of luck as it came in sizes only up to 750cfm. Now, Holley has addressed that with this "made-for-strokers" 950cfm carb. The radiused venturies offering smooth airflow are what distinguish a Pro Series carburetor from other Holley list 4150s.

If you were to label anything about this combination as exotic, you may look to the oiling system.

Charlie's Oil Pans supplied the 7-inch sump design which carries a simple static pick-up with a side exit due to the relocation to an external feed/pump. This pan will fit all Mopar body styles.