Big Block 511 - Tame Street Motor

The seasoned 440 block was bored .055 over, final honed and final cleaned

440source Forged steel crank with a throw of 4.25 inches

Forged BBC H-Beam rods with measure 7.1" long

Forged Crank being installed, note the plug in the pickup tube boss

Minimal Clearancing was needed with the BBC journals

A static pickup was installed in the 440source oil pan

Mopar Performance "452" cylinder heads before being sent to Modern Cylinder Head for cnc porting

Motor assembled and topped off with an older TM7 intake awaiting installation

Everyone has their own idea about what a street motor is these days. Some people think it is a small block with an “rv cam” and a Holley 450 atop. Those same people probably think an ashtray is a performance item. Personally, I believe it is the biggest baddest motor you can tolerate driving on a cruise night.

When building a street motor, you must first decide its purpose. Is it going to be used for long trips? Just go around the block (really, really fast!)? Or somewhere in between? What your goal is depicts the type of components to use. For instance, you won't use aluminum rods in a motor you plan to make several cross country runs and go 100,000miles without ever taking it apart to freshen up.

Each individual also has a budget to work with. It is unlikely that a local convenience store clerk is going to putt around town with a Pro Mod motor under the hood of his car.

For our build, dubbed Tamed Street Motor, we wanted an engine that cost under $10K to build and could go through years of abuse without having to be freshened up every couple thousand miles.

Short block

We started off with a seasoned late-70's 440 block. The block had previously been bored .030 over and the bores were worn, so we had it bored to .055 over. A set of ARP main studs were installed to secure the main caps in place.

Now the easiest way to make more power is increase displacement. We called up 440source and ordered one of their stroker kits. The heart of their stroker kit is their own forged 4340 steel crankshafts. The crank in the kit we ordered has a stroke of 4.25”. And to help make fitting such a stroke in a stock block the crank features BBC rod journals. With a stroke of 4.25” combined with a bore of 4.375” gives us a displacement of 511ci.

Stock rods would be at their limit in both strength and length with the plans we had for this motor. The 440source 7.1” Platinum Series H-beams meet the challenge laid out before them. These rods are held together with ARP2000 cap screws. These rods are lighter than stock rods weighing only 800grams. The small end is bushed for floating pins and they have a BBC big end. Attached to the end of the connecting rods is a set of ROSS forged pistons. The pistons have a dish of 27cc to give a pump gas friendly compression ratio with the elongated stroke.

Clevite 77 bearings and Childs and Albert Total Seal piston rings complete the stroker package and are durable to ensure many years of driving. Providing the life blood of the RB that will lube those bearings is a high volume oil pump from Melling sucking through an external static pickup mounted in a 8qt deep sump pan.

Top End

Even the biggest of motors isn't going to make any power without a good flowing set of cylinder heads. Edelbrock produces the Mopar Performance “452” cylinder heads based of their own Performer RPM heads and they flow decent out of the box and are an improvement over stock heads, but we wanted more. Modern Cylinder Head stepped up and provided us with a set of his CNC ported MP “452” heads. Flow has been increase drastically in all areas of valve lift. Modern also added his own choice of springs to handle the larger than stock solid cam Scott Brown supplied us with. A set of ARP 7/16 head studs clamp the heads to the block.

Scott Brown had a cam profile that met the needs of our hungry wedge. With .607 lift and a duration of 274 @ .050 it'll be giving the rocker arms a workout. Working out a lot especially on a street motor destined for high mileage, aluminum rockers would pass out long before the race was finished. We needed a marathon runner, so a set of Isky ductile iron bushed rocker arms we ordered up. Pushing the Isky arms is a set of Crane 3/8 pushrods.

With dozens of intakes available for the Mopar RB, one is tried and true and must not be forgotten. Edelbrock got the design right decades ago when they came up with the TM7. Often over looked due to its age, the TM7 makes more horsepower than the more recent Torker intake and as much as most modern intakes for the RB wedge. To form a match made in heaven, the also overlooked and “outdated” Holley 830 DP was mounted atop the intake (happy intake).

Performance

As I spent the past year making sure everyone on the street knew not to mess with my mighty Mopar, it was time to take my convertible to the track to see what the bad 511ci motor could do. I first weighed the car with myself and half a tank of fuel in it. The expected heft was to be pushing past 2 tons, but pleasantly came in a little lighter at 3840lbs. So I saddled up my horse and made my way to Lebanon Valley Dragway.

A few months earlier I had made a last minute attempt at the 1/4 mile while attending a carshow at Englishtown. With the old dry street tires, the best I could peddle the car to was a 12.60 @ 112. But this time would be different. This time I would be prepared.

The convertible now sported a brand new pair of Hoosier 275/60R15 Drag Radials mounted on a pair of Weld wheels. With 20lbs in the tires, I entered the burnout box. I heated up the tires and staged the car, only torquing the motor up to 1500rpms Last yellow light starts to go out, I launch softly and spin the motor up to 7000rpm before shifting my Torqflite into 2nd followed shortly by 3rd at the same rpm. The shakedown run yields an honorable 11.70 @ 116.27mph.

During the run I could feel the motor choking from the small 1-7/8" headers, 2-1/2" exhaust, and 830cfm carb. Second time out I torqued the motor to 1500rpm again, but shifted at 6100rpms. My decision paid off, running almost a 1/10th quicker at 11.61 @ 116.90mph. For my third and final pass of the day, I torqued the motor up to 2000rpm and shifted at 6100rpm. I cut a better 60' at 1.69sec (both previous were 1.75sec) and run the bust run of the day with an 11.54 @ 116.35mph. All this while still sporting the 3.55 gears.
Eat that Tony...