Cadillac Engine - Mack Daddy Caddy

"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."