Better Heads And New Rockers To Boot
Magnum V-8 engines are great power producers. They offer lots of torque at low rpm and have a durable bottom end that can serve as an excellent platform for a workhorse engine or a high-horsepower racing powerplant. If you can overlook the horrific fuel economy, the 5.2L and 5.9L Magnum V-8 engines are generally likeable motors.
But if you're an owner of a Magnum V-8, you probably already know that it's not all a bed of roses with this engine. Almost certain head problems plague 5.9L (360ci) models, but 5.2L (318ci) owners should be wary as well. Heads are such a problem on Magnum V-8 engines that Dodge and Jeep dealers tend to keep them in stock.
The head problems usually lie between the valves. The extra pressure and power and the different stroke of the 5.9L engine tend to make it much more susceptible to issues than its 5.2L brethren.
Since we have a couple of these engines embedded in our fleet of vehicles, we've experienced more than our share of head gaskets blowing and heads failing. Our last pair to blow was on a daily-driver, and with 50,000 miles on the engine the temperatures were going through the roof and white smoke was blowing out the back-sure signs of head dilemmas. Our reliable engine masters at Jeeps R Us came to the rescue again, pulling our heads and sending them off to D&H Automotive Machine in Capistrano Beach, California, to see if they could be salvaged. But the report came back of numerous cracks in both iron heads.
With the recommendation of D&H, we tracked down a company called Cific International. Cific's heads are stock replacement on Magnum V-8s, but they've managed to thicken the metal around the water jackets and get more material between the valves. Having no prior knowledge of a simple head solution (save for a custom modified head) for the Magnum V-8 engines, we were eager to get our hands on a set for ourselves. It was a little uncharacteristic of us to rip something open and not modify it, but we resisted and kept ourselves from enlarging intake valves and popping in a lopey cam. Besides, "stock and working" is a great modification over "broken."
We were so close to having everything buttoned up when our true nature got the better of us. It couldn't hurt to add some more efficient roller rockers from Crane Cams (hey, the valve covers were already off) to our valvetrain. And the requirement for taller valve covers would give us an excuse to put some more impressive looking Mopar aluminum valve covers on our Magnum 5.9L.
Maybe we aren't so good at keeping things stock, but we sure do like the upgraded package that will keep our engine lasting longer and running a bit more efficiently.