507 Cadillac V 8 Engine - Mack Daddy Caddy

Some guys prefer to take the road less traveled, steering clear of the herd to do their own thing. Sometimes such a decision can be viewed as eccentric, but once in a while, such an approach can lead to a unique kind of success. In the world of engine building, we have the mainstays: Chevy's big- and small-blocks. You might think building Mopars, Buicks, Olds, or Pontiacs is outside of the mainstream, but some guys see the potential in the more obscure. Richard Potter is one of those guys, and his outfit, Cadillac Performance Parts (CPP), is dedicated to making the most from GM's largest and most overlooked passenger car engine series. Last year, CPP sought to show the world the potential of the big Caddy mill by entering a 507-cube example in Popular Hot Rodding's annual engine building competition, the Jeg's Engine Masters Challenge. And while it finished out of the top three, it made very respectable power with 779.9 hp coming in at 6,300 rpm and 698.5 lb-ft of torque at 5,200 rpm. Performing such a feat on 91-octane pump gas captivated an audience of cynical veteran engine builders, so we know you're going to love it.

This custom-built engine was the result of visionary dedication to an overlooked powerplant, with untold hours of custom engine building at its best. From here, we'll let engine builder Richard Potter tell his story:

"Our primary goal was to simply show the potential of a very well-designed and overlooked American V-8 by bringing a state-of-the-art entry to the Engine Masters Challenge. The build required grueling hours of labor, lots of love, and a ton of math and planning. We are dedicated to the advancement of the Cadillac 500 engines. Since we build most of the parts, we figured we may as well knock heads with the engine builders that the sport is judged by, and this competition gave us the opportunity.

"Our team was put together according to what they are capable of bringing to the table, and bring it they did. Lots of the build theory and formulas were the brainchild of Stan Justus from Stallion Racing Components. For those who don't know him, he designs Cup, ARCA, and high-end drag racing cylinder heads, intakes, and carbs. Anyone who spends more than 30 seconds talking to Stan will realize that he is the real deal, or would just be lost all together. We actually had the engine 100-percent designed on paper with a build formula before starting, and it went together smoother than any to date. With all the preliminary research, it fell together without so much as needing to file, relieve, or clearance anything.

"Some of the formula came from Tim Ottenger of T&G Machine-an avid ARCA cylinder head machinist, porter, and valvetrain specialist. Until I met Tim, I thought I was current on cylinder head machining. As with Stan, a short conversation with Tim will leave you thinking. Tim and Stan often work together on projects, but this is the first time all of us worked together in one deal. Also involved in developing this engine was master machinist and designer, Robert Pelfrey, of PMR Innovations. He's a longtime friend and business associate who makes a lot of our rocker parts for us. Robert worked many long hours making sure everything I designed became a functioning reality. Finishing this project on time would not have been possible without him. It seemed the more I got Robert into this build, the more interest he took in it. It soon became like a sickness for myself and the others-a darned exciting one, though.

"What made our build so difficult is that we can't call a mail-order supplier and order a bunch of stuff to throw an engine together. We are fortunate, though, to have drawn the interest of several performance parts companies over the last few years, helping to spur the development of many of the performance parts used in this engine. We feel that parts availability for the Cadillac will continue to grow, as will the popularity of the big Cadillac. Five years ago, we'd call some big manufactures to have some stuff made, and they'd laugh, then hang up. Now, they are beginning to see the potential. We have thousands of glory-free hours in our research and development, and are very fortunate that demand is too small to grab the attention of the bigger companies. We have been able to tool right along, without fear that the big boys will stomp us out.

"With a 2,500 to 6,500 rpm powerband in mind, we figured mass reduction was a major player. The less the engine has to drag with it, the more it can lean against the machine. It may be only a few ponies, but these things are won and lost by less than a few points. The billet crank we had made weighed-in at 2 pounds more than a stock crank, after being knife-edged and gun-drilled, so it went on a 165-hour, 24-pound diet. Balancing the crank was a story in itself. Pee Wee at Riverside Machine allowed me to balance the rotating assembly countless times so that we could remove material on-site from the counter weights, rather than drill a bunch of holes in them to bring it into specification. After being worked by hand to a chrome-like finish, it went to Calico Coatings for the Teflon coating. I took it there, dropped it off on second shift (which does the surface prep for the next day) and left with it at around noon the next day. They knew we were in a bind for time and really stepped-up to the plate.

"There were several other ways we attempted to reduce drag. The main bearing size was reduced from the massive stock 3.250 inches to Chrysler's 2.750-inch, Hemi/440 size. This was done by making custom saddles out of cast-iron thick-walled tubing, and machining them to fit the block as if cast there. The thrust of the block itself only needed .040 inches off each side to accept the Chrysler thrust bearing, and it was done in-house on our Van Norman machine center. The rod bearing size was reduced from the factory 2.500 inches to the 2.200-inch big-block Chevy size. The assembly used a piston-guided rod, and ran 0.175-inch side-clearance to free up any rubbing action. There again, it's one of those 'couple here and there' horsepower, but it all adds up. A Teflon-coated full windage screen was painstakingly fitted under the main bearing girdle to keep it as close to the counterweights as possible. This feat itself took over 40 hours. The girdle, screen and oil pick-up all came off as one unit.

"This year was our first dealing with Mahle pistons due to their sponsorship of the Engine Masters Challenge program. We've known about the Mahle's outstanding quality through Stan and Tim's experience with circle track racing, however, I have never witnessed absolute dedication like this firsthand. We took a cylinder head to Mahle after the chamber was prepared, and they immediately digitized it on a CMM while we waited. They then made a custom piston to mirror the combustion chamber perfectly. We rattled this engine extremely hard with the super-lean condition we faced. The evidence was up in the mains and caps, but the pistons looked like brand new afterward. We figured they would be peppered like a normal piston, but we were greatly surprised.

"To link the crank to the piston, we used a Scat 7.100-inch big-block Chevy rod with a 0.990-inch piston pin. I was impressed with the finish machining and end-weights, as they were dead on. Scat has since become more interested in the Cadillac application, and now makes a drop-in Cadillac H-beam rod, a much-needed item.

"Like all of the big Cadillacs, the OEM block we used is a high-nickel casting, and has massive bore capabilities. We have gone 0.200-inch over [4.500-inch bore] with these engines, with a half-fill of the water jackets, and up to 4.440 inch with no fill. Keep in mind that the Cadillac is a 5-inch bore-spacing engine, and is most likely the strongest stock OEM block ever made. This particular combo was sleeved down to a 4.250-inch bore size [4.300 inch is stock] and we used a 4.470-inch stroke for a total of 507.2 cubic inches. Making power in the lower rpm is aided by the stroke, and with a 6,500-rpm limit, the long stroke helps more than it hurts. We make and sell torque plates for these engines and incorporate all ARP fasteners to ensure strength and accuracy.

"We machine our own cam blanks, and increased the journal size to 52mm [2.051 inch] from the dinky little 1.750-inch stock specification. Competition Cams graciously grinds the cams for us according to Stan Justus' specs. The cam uses a standard Ford 351M roller bearing. We bored the block for this cam bearing dimension, and added bronze bushings to the lifter bores. A Cadillac oils the mains off of the lifter galley like a Chrysler 440, so if you kick a pushrod, you have no oil pressure. We use 0.080 to 0.100-inch holes in the bushing to minimize excess oil up top. We chose to run a set of Crower's High Seat solid roller lifters because of their reputation.

"The cylinder heads were another story in themselves. Though we are developing a cylinder head casting of our own design, a set of Bulldog castings was utilized on this engine, since our new heads weren't ready. These heads were first completely stripped of seats and guides, and heated in an oven to 800 degrees. Next, the combustion chambers were welded almost completely up. The next step was to re-heat treat the heads, then reshape the combustion chambers according to our own design ideas. They ended up with a chamber volume of only 39cc's, far from the original 76cc size. The intake ports were raised and the floor filled with epoxy. A much smaller exhaust valve was used, and Ferrea made us some hollow-stem stainless valves for the project. The finished head form is basically like our new Boogie Man heads, but in a one-off form. Much of the same characteristics are cast into our head, without needing heavy mods. The valvetrain was basically an unaltered item, one we have been making and selling for about eight years. T&D makes our rocker arms, and we make all the cradles and hardware. Using a solid roller did make us want to go to our 4340 version instead of our standard T-6 items. The springs are Manleys, hijacked from an SB-2 ARCA engine.

"The available choices for intakes are rather slim. We had two to choose from, and both needed a lot of work for this application. The Bulldog intake manifold plenum needed help, and the ports are way too big, and they really needed to be a couple of inches higher. Our Boogie Man intake is designed as a Pro-type 2x4 intake and would have been a poor choice as-is, but the manifold is basically a blank slate on the inside. Kinda figure an apple crate with legs. I first got the floor like it needed to be with epoxy. Then I made a plaster core around which to pour epoxy inside the intake. It was designed to just fit down inside the intake, with all the right shapes and runner sizes. After the final epoxy was poured, the plaster core was simply chipped out. The radically modified manifold took untold hours to complete, and weighs a hefty 64 lbs. We'll be glad when our new single-plane intake is finished, because I don't want to have to do that again.

"The carb we started with was a three-circuit Dominator. Since high-end carbs are Stan's specialty, we gave him a roll at the dice. After changing circuitry, metering plates, boosters, blades and all, we had a carb that made 22 more horsepower compared to a stock, tuned one. Not bad for a bolt-on. I also got a lesson in what air bleeds actually do as well as a crash course in jetting and tuning.

"Our reverse-flow cooling system was the most obvious system showing externally on the engine, and it looks like something from the space shuttle. In a perfect world, an engine block wants warmer coolant than the head does. Since all the parts are designed to run at higher temperatures for things such as piston expansion, we ran the 160-degree coolant supplied by the dyno into the cylinder heads first. I modified a Meziere electric pump to run outward to a pair of fabricated one-into-four aluminum manifolds, which branched off into four ports going into the heads, each under an exhaust port. The cross-sectional area in inches was compared to the area of the passage from each head into the block, and the passage was kept to an amount just below what was coming in. This was to make sure the head stayed full of coolant, and to prevent gas pockets. The coolant return came from the center casting freeze plugs on the block, and runs up to a dummy thermostat housing. It was vented into the block to bleed the system of air also. We toyed with the amount of return to obtain an acceptable temperature in the block, while keeping the heads at the desired lower temperature. I wish we had more time to experiment with hotter temperatures, as I feel there is more power to be had there.

"We had an opportunity to showcase our engine's capabilities in the Jeg's Engine Masters Challenge competition. We lost the crank hub/balancer, and that was disappointing, but overall we were very happy with the results. We showed folks that these Cadillac engines are just as capable as any other engine. That was our first priority, and the main reason this particular engine was built. I'd say we'll be lurking in the shadows until next time."