Cadillac Engine - Mack Daddy Caddy

One visionary engine builder takes the road less traveled with a 779hp, 507 cubic-inch pump-gas Cadillac.

By Steve Dulcich

Photography by Johnny Hunkins

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.