Project 505-Inch Short-Block - 505 Super Victor

The Plan
Mancini Racing recently started to offer killer deals on CNC ported heads, so we decided to see how they would perform on our 505-inch short-block. To top things off, we contacted Edelbrock for one of their brand-new Super Victor intake manifolds with the 4500 carb flange. Staying with the hot street plan, we hooked up with Comp Cams to get one of their Xtreme Energy street roller camshafts. We also took this opportunity to try out a Reher-Morrison shear plate, the new valve cover gaskets from Moroso, and some trick new valvespring retainers from Comp Cams.

The Short-Block
Project 505 was originally built for the Modern Max Wedge article that ran in the August 2007 issue of Mopar Muscle. It is based on a thick-wall, '77 production 440 block with a 4.250-inch stroke crankshaft from 440Source, a set of 6.800-inch-long Chevy rods from SCAT, and forged pistons from Diamond Racing. Those of you with sharp memories will recall that this short-block had 13.5 compression in the Modern Max Wedge article, but for this round of tests the compression dropped down to 12.5:1 with the Mopar heads. The pistons have stayed the same since the Max Wedge buildup, but the Mopar heads have an 84cc chamber as compared to the 75cc chamber in the Indy heads, so the compression ratio dropped a point.

This motor has seen a lot of dyno duty over the last couple of years so we learned to leave the short-block dressed up in dyno friendly parts such as a deep oil pan with a dual line Milodon pump, an external oil filter, a Jesel belt drive, and an electric water pump. These parts are not necessarily what you would find on a hot street car, but it's nice to have the durability that these parts bring to the table when we're doing a lot of dyno testing.

The Jesel belt drive for the camshaft is an expensive upgrade over a conventional timing chain, but it sure makes life easy on the dyno when we need to change cams or adjust the cam timing. One other item that we've been using lately on our dyno engines is a Jesel belt driven distributor. Once again, this is a fairly expensive upgrade from a stock type distributor, but the central location provides great access and we don't need to wrestle with the distributor every time we pull the valve covers to inspect the valvetrain. The belt driven distributor does not have any advance mechanism, so we're running a flat timing curve. As soon as the engine fires up, it goes straight to full advance and stays there throughout the entire rpm range. One thing we have noticed with this setup is that the timing is rock solid when checked with a timing light.

Headed In The Right Direction
The Mancini Racing-supplied heads are basically an aluminum version of the original 915 cylinder head with an improved port design for much better flow. These heads have a closed 84cc combustion chamber with a large quench area, and the valve diameters have been enlarged to 2.14/1.81 inches respectively. To produce these heads, Mancini Racing starts off with a Mopar Performance PN P5153524, which they then send out to Modern Cylinder Head for full CNC porting. The CNC porting increases the airflow to 325 cfm at .600-inch lift on the intake side, and 230 cfm on the exhaust side. These heads have a straight spark plug location that is similar to a stock cast-iron head rather than the angled plug that most aftermarket heads have. The straight plug design fits many header designs better than the angled plug heads since many headers were originally designed for stock heads.

The CNC porting that was performed on these heads increases the flow without significantly increasing the port size. There is an optional porting program that will open the heads up to the Max Wedge size, but we wanted to stay with the standard size on these heads since our focus was more on street performance than drag racing. The Max Wedge size ports will increase the airflow and the power output, but then you must use an intake manifold and intake gaskets with the larger Max Wedge sized ports. Since nobody has produced a factory bathtub type intake gasket with the larger Max Wedge port size, there is no good way to seal off the valley area when using Max Wedge ports on stock replacement heads. Maybe the aftermarket will finally step up and produce a stock bathtub type intake gasket with the larger port size so that people can start to bolt large runner, single carb intake manifolds onto stock type Max Wedge heads.

We know from experience that standard port sized heads on a 505-inch short-block will produce a torque peak around 4,000 rpm. Given that information, as well as the compression ratio and exhaust header diameter, we were able to call up Comp Cams and tell them what they needed to know to grind us a cam that would work well with our motor.

Camshaft And Valvetrain
We knew that the size of the cylinder head ports would limit the power peak to less than 6,500 rpm, so there wasn't any reason to install expensive valvetrain parts designed for speeds higher than that. The street roller camshafts from Comp Cams are designed to provide high power output from a cost effective and durable valvetrain. These street roller profiles are easy on the valvesprings, but you do still need to use a valvespring that is designed to handle the higher loads that a solid roller camshaft generates.

Comp Cams has a wide selection of street roller cams in their catalog, but when we contacted them about a cam for this engine, they told us that with 505 inches and 12.5:1 compression ratio, we would be better off with a cam that is a little larger than any of their current catalog offerings. Fortunately, Comp has a wide library of Xtreme Energy roller profiles on hand, so they were able to quickly come up with a profile that matched our needs. The cam that the Comp engineer recommended for us was just one size larger than the XR292R in their current catalog. Our cam, which most likely would be called an XR298R if it was in the catalog, uses a 4877 intake lobe and a 4878 exhaust lobe. We had the camshaft ground on a 108-degree lobe separation angle with the intent of installing it two degrees advanced. The cam lobe specifications are 260/266 degrees of duration at .050-inch lift with gross valve lifts of .627 and .637 inch with 1.60 ratio rocker arms.

The Mancini heads are designed to operate with flat tappet camshafts and a maximum of .600-inch lift as delivered, so we needed to replace the valvesprings with a set that would be compatible with our roller cam. The valvesprings that Comp recommended we use with their roller cam was PN 26094-16. These 26094-16 valvesprings are good for up to .650-inch lift, which was just perfect since the combination of 1.60 ratio rocker arms and the tight .016-inch valve lash on the cam gave us a net valve lift of .620 inch. We had decided to run 1.60-inch-ratio rocker arms rather than the stock ratio of 1.50, in order to make a little more power. In addition to the extra lift, the 1.60-inch rocker arm shifted the pushrods away from a clearance problem that we saw when we mocked up the engine with 1.50 ratio rocker arms.

Comp Cams has recently introduced a new tool-steel valvespring retainer that has some very nice features, so we wanted to give them a try as well. The unique shape and material of these new retainers results in a very lightweight design when compared to previous steel retainers. The retainers, which we used, were PN 1732-16 and they only weighed 22 grams each. This is within a couple grams of what titanium retainers weigh, but these tool-steel retainers are significantly less expensive than titanium. Not only are these retainers lightweight and relatively inexpensive, but the thin design provides a lot more clearance to the rocker arm. That is a win, win solution which is hard to beat.

For this buildup we went with a set of stainless steel rocker arms from Rocker Arm Specialist (RAS). These rocker arms aren't very well known in the Mopar world but they are a great product that we have used for many years in different project engines. The RAS rocker arms come complete with heavy-duty shafts and hold-downs, as well as high quality adjuster hardware. The stainless rocker arms have a roller tip and a bronze bushing for the shaft. They are an excellent choice for a street roller since they'll handle the high forces of a roller cam valvetrain and they have the ability to live for a long time on the street.

Intake And Carb
Edelbrock recently introduced two Super Victor intakes for the RB motor, PN 2891 for standard port heads and PN 2893 for the larger Max Wedge sized ports. For this motor we needed the 2891 with the smaller runners since our Mancini Racing heads had the smaller, standard-sized ports. The difference between the Victor 440 and the new Super Victor intake is that the Super Victor is slightly taller with a larger plenum that is designed for a Dominator carb.

The Super Victor intake weighs 14 pounds, and is quite tall with a pad height of 6.350 inches. That height is about .250 inches taller than the Victor 440, which is a fairly tall intake itself. The carburetor mounting flange is not angled on this intake since most race engines are installed fairly level in the chassis. The runners are about 7 inches long, which is fairly long for a single plane intake manifold. The carb flange is a modified cloverleaf design which might not mate up with most carb spacers, but that should be easy to fix with a grinder.

The fit and finish of this intake was very nice, so we didn't do anything other than bolt it on our engine right out of the box. The Super Victor is tall enough that you can peer down the runners from the plenum and see into the ports in the cylinder head. A close inspection showed that we did not have a perfect port match between the runners and the head ports right out of the box, but they looked close enough so we ran it untouched.

Our Holley Ultra HP Dominator has performed great during the last series of tests we conducted, so we just adjusted the jet size and bolted it back on this motor. We reduced the main jets by four sizes in order to lean out the carb to work with the smaller runners in the Super Victor intake, and then we were ready to go.

On The Dyno
The first order of business on the dyno was to check the cranking compression. We always check the cranking compression on new combinations in order to give us a baseline that we can keep track of over time. We considered it a good omen when all eight cylinders cranked right at 200 psi with very little variation between them. Our plan was to run all tests with the ignition timing locked in at 37 degrees of advance, so we played it safe and used race gas. It is possible to get by with pump gas at 200 psi of cranking compression, but we didn't want to push our luck during these tests since we knew we would be thrashing the engine.

The engine fired right up with a very healthy sound as soon as we hit the ignition switch. At a 2,000-rpm fast idle, the engine had a steady 15 inches of vacuum, but the vacuum number dropped sharply once the idle dropped much below 1,500 rpm. Of course, with a solid roller camshaft it isn't a good idea to allow the engine to idle much below 1,500 rpm, since the lifters need plenty of splash lubrication to keep them operating smoothly.

Once the engine had warmed up and everything passed a final inspection, we pulled the lever and watched the needle swing around the dial. With the standard port-window heads on 505 inches, we knew the torque number would be good, but we were still a little surprised to see 637 lb/ft at 4,000 rpm on one of the first pulls. The best torque reading we saw during the dyno pulls was 643 lb/ft at 5,100 rpm, but many of the pulls were in the 620 range. Peak horsepower readings were right around 680 at 6,000 rpm depending on the dyno pull. The very best number we saw was 683 at 6,200 rpm when using a Wilson spacer under the carb. Several other runs hit 680 or 681 at speeds between 5,800 to 6,100 rpm. It isn't uncommon to see the peak numbers vary a little during testing since there are so many variables involved. We tried several different carb spacers and played with a couple of different carbs during our test session, but nothing seemed to change the numbers much from the 640 lb/ft of torque and 680 hp levels. All in all, we were very pleased with the power that this combination made on the dyno-680 hp in a 3,400-pound car would give a 5:1 weight to power ratio which is enough power to run 10 flat quarter-mile times at 138 mph.

Wrap Up
This was one of those test sessions where we answered some questions and raised a few new ones. We certainly demonstrated that the street roller camshafts from Comp can make a lot of power without breaking the budget. In hindsight, we probably could have gone one size smaller on the cam and had a little more vacuum at idle without giving up much top end power. So if you're thinking of running a Comp street roller in your 500-inch daily driver, you might want to go a bit smaller than our choice. The nice thing about using a roller camshaft is that if your first choice wasn't perfect, you can quickly slide in a different camshaft profile and you do not need to buy new lifters.

We also learned during this series of tests that the new Super Victor intake is a very nice intake that was easily capable of making our power goals. We did not have a Victor 440 intake on hand to do a comparison test with, which in hindsight might have been interesting. We are now wondering what the power difference would have been between the smaller plenum Victor 440 intake and the large plenum Super Victor.

But this is the way it often goes with dyno testing. We usually learn a lot of interesting things, but we also often come away with some other items to ponder. Good thing there's a new issue of Mopar Muscle every month! That gives us the opportunity to keep trying new things and to tell you what we learn.

Mopar Performance has had an M1 intake manifold in their catalog for a number of years that has standard sized ports and a Dominator flange. PN P4529725 is the version that fits RB motors while PN P4529724 fits the smaller B motors. We thought it might be interesting to try the 725 intake on this motor while we had it on the dyno just to see how the older Mopar design stacks up against the new Super Victor.

The 725 intake is almost an inch shorter than the Super Victor, which means it might just fit under a stock hood. Since it is shorter, the 725 intake also has shorter intake runners, which in theory should move the torque peak up a little bit. When placed side by side with the Super Victor intake, we immediately noticed a few differences. Not only is the 725 intake shorter than the Super Victor, but the carb pad on the 725 intake is tilted forward at 3 degrees to keep the carb level in a production vehicle. The 725 intake also has built-in mounts for the factory style ignition coil, which is something that the Super Victor intake does not have.

We bolted the 725 intake onto our motor using the same Reher-Morrison shear plate combination and the same Holley 80672 Ultra HP Dominator carburetor. Everything on the engine, including the carb jetting, was left the same for the dyno pulls with the M1 intake since we didn't see any indication that anything needed to be changed from the settings used with the Super Victor intake.

The dyno results with the M1 intake were virtually identical to those obtained from the Super Victor testing. We saw a similar 640 lb/ft of torque at 4,100 rpm with maximum power down a tiny amount to 680 hp at 6,100 rpm. We were mildly surprised that the M1 intake generated basically identical results to the Super Victor intake, but not shocked. Both intakes have very similar shapes with the only difference being the slight difference in intake runners. The shorter runners of the M1 intake didn't affect the dyno numbers but it might change how the car launches off the line. Unfortunately, we won't know that until we do an intake comparison at the track.