We had to add a small piece...
We had to add a small piece of Mallory in one counterweight to get the crank balanced properly. Final bobweight was right at 2,200 grams, which is great for a big-block with steel rods. The rods we used weighed 775 grams, but there is a lighter version available from 440Source that only weighs 730 grams.
We had gotten the wrist pins and the rings from Diamond when we purchased the pistons, but we still needed bearings. For those, we ordered a set of coated pieces from Callies. We have used the Callies coated bearings in our recent engine builds for just an added layer of protection. Once we had all the short-block parts on hand, we hauled them over to Gray's Automotive Machine in Tigard, Oregon, so they could work their magic. The block was treated to basic high-performance machine work, which includes the installation of main studs, an align hone, a .030-inch overbore, and then honing with a torque plate. The block was then decked just enough to keep the pistons .005-inch down in the cylinder at top dead center. Once the machine work was finished, the block was thoroughly cleaned and then the short-block was assembled.
906 Heads And An MP 557 Camshaft
For the baseline configuration, we used a set of 906 heads we've had around for a few years. These are basic 906 heads with a set of 2.14/1.81-inch valves, and some good quality Comp Cams 939 valvesprings with Comp retainers. They have never been ported, but the bowls were hogged out to match up with the bigger valves. These heads haven't ever seen a flow bench so we don't know how well they flow, but it probably isn't anything fantastic. In other words, these old 906 heads are basically just like countless other cast-iron heads that are bolted on to the average guy's big-block.
To go along with the old-school 906 heads, we slid in a .557-inch lift solid flat-tappet grind from Mopar Performance. The MP 557 is a classic grind that has been around forever, so we thought it would make an excellent baseline camshaft. Our original plan was to test the 557 against some modern camshafts to see just how it compares, but we ran into a time crunch and the only dyno pulls made were with the 557 cam.
To complement the 906 heads, we used an unported Mopar Performance M1 manifold. The M1 manifold is a good choice for this type of smaller street/strip type of motor. While it might not match up with a more modern intake, it seems to work pretty good when combined with a modest flat-tappet cam and a good set of headers. This baseline combination of parts is pretty close to the combination listed in the Mopar Performance catalog as the Super Street 10.90-second engine. The MP recommendation: an RB block with the 557 cam, an M1 manifold, a 750 carb, and 11:1 compression. That is basically the same combination that we built here, but in the smaller B-block and with just a tad less compression.
Dyno Results With 906 Heads
Once the engine was fully assembled, we strapped it to the dyno at Gray's Auto Machine to see just how well the combination worked. Ignition timing was set at 36-degrees advance, and the Holley 750 was jetted to give us an exhaust gas temperature of 1,350 degrees. Once the cam was broken in and the fluid temps brought up to working range, we pulled the lever to see how it would do. The average of three runs gave us a peak torque of 500 lb-ft at 4,800 rpm and a peak power reading of 500 hp at 6,200 rpm. While the 557 cam might be a tad big for street driving, this overall combination should be a great setup for a low maintenance bracket car.
 These 440Source rods have...  These 440Source rods have a big 71/416-inch ARP rod bolted in them that needs to be torqued until they stretch .007-inch. That is roughly 75 lb-ft of torque when using moly-lube. Remember, the different lubes, such as regular motor oil, will give a different torque reading for the appropriate stretch. We use a gauge from ARP to measure rod stretch. |  We used a deep 8-quart oil...  We used a deep 8-quart oil pan from Milodon for the dyno testing. This pan might be a bit deep to run on the street, but Milodon has plenty of other models to choose from. This motor runs the standard 3/8-inch internal pickup. |  The assembled bottom end shows...  The assembled bottom end shows the ARP main studs holding down the stock main caps. Nothing trick here, just good machine work and careful assembly techniques. Button it up with the oil pan and head for the top. |