"I've never been able to blow one up." Many times, a conversation revolving around a Slant Six engine results in that very quote. It's the Leaning Tower of Power, it's indestructible, and the Slant Six saw duty in everything from the small A-Body to the Ram pickup.
For that reason, we thought that a follow along with a rebuild of one of these engines was in order. Some time ago, we got a call from Chris Holley, an instructor at the Pennsylvania College of Technology, in Williamsport, Pennsylvania, telling us about a Dart that the college had just acquired. We ran a Hidden Treasures article about the Dart in our April 2013 issue, and when the Dart's engine was ready for a rebuild, it seemed like the perfect follow along for us.
As we said in our Hidden Treasures article, the engine is a 225-inch Slant, with a 904 transmission bolted to it. Disassembly was a little harder than planned, as pistons number five and six were seized in the heavily rusted and pitted cylinders. By honing the visible areas of the cylinders by hand, and then hammering the pistons up and down in the cylinder, we eventually freed the pistons. The block was stripped, and during removal of the head, we learned that several of the valves needed some persuasion in their removal as well. The head, block, crankshaft, and rods were then sent to the college's automotive machine shop for the necessary machine work.
The block was decked .060-inch, and the cylinders were opened up to 3.460-inches (.060-inch oversized). The head was also milled .060 inch, and treated to a three-angle valve job. The rods were equipped with ARP rod bolts, and then resized, and new .060-inch oversized cast pistons were then hung on the rods. The factory steel crankshaft was in good condition, so it just needed a good cleaning and a polishing of the journals. The large amount of metal removed from the block's deck and the cylinder head (.120 inch total) in conjunction with a .045-inch crush head gasket, resulted in a 9.37:1 compression ratio. Although some might consider this low, it is actually a nice one-point increase in compression over the factory specs. Since the head and block were milled, the pushrods were now going to be too long. To correct this, the rocker shaft was shimmed .035-inch to correct the rocker angle and not have the valve train bind during operation.
1. The Slant Six looked a little dirty but was in complete and unmolested condition. While the engine looked good, it was later determined that the engine was seized due to the poor preparation for its storage.
2. The lack of attention led to nine of twelve valves becoming seized in their valve guides. Various attempts to free the valves were all unsuccessful, it was quickly determined the engine would have to be pulled for a complete rebuild.
3. All six cylinders were filled with a water/gas mixture. During disassembly pistons five and six were seized in their respective cylinders. It took several hours of hand honing the rust in the cylinders and then using a hammer and drift to drive the pistons up and down a little at a time.
4. The engine was bored .060-inch oversized, to restore the cylinder bores to a true round and pit free surface. The block was decked .060-inch to provide a flat surface and to increase the compression ratio slightly. The factory replacement camshaft was installed into the block in the straight up position.
5. The stock crankshaft was polished and placed back into service, and the short block was assembled to the factory specifications. The new oil pump was packed with Vaseline to help with the priming of the oiling system.