Modified Mustangs & FordsHow To Engine
Ford 390 Block Surgery
Turning a mild 390 Ford engine in to something wild
In the last installment of this continuing saga, we ended our dynosession at Roush Racing when the crank decided it'd had enough, just aswe were getting warmed up. The crank destroyed the rod bearing, whichmelted to the rod and crank. The end result was two ruined rods. Onethrew its cap through the side of the block and subsequently broke inhalf.
After a thorough inspection of the block, we found the following:
1. Block skirt "windowed;"
2. Small crack and pair of brinelled spots in opposite side of blockskirt;
3. Two cylinders damaged at the bottom--one with crack and dimple inwall;
4. One lifter bore damaged at bottom;
5. Camshaft retainer bolts broken off flush with the front block face.
All of the important parts of the block were intact and without damage.We decided to repair the mentioned trouble spots and build anotherengine. Let's look at what it took for the guys in Jack Roush's RaceEngine Shop to save our damaged block.
Two of the processes we've had to go through can induce some degree ofdistortion to the cast-iron structure. By far, the greatest degree ofstress would come from the welding. In order to successfully weld iron,it's necessary to preheat the work piece. Then, when the whole block (inthis case) was heated, the actual welding could progress.
Chris Razor of Hi-Tech Welding Inc. was chosen to do the work. His reputation includes some very sensitive work for Ford in past projects.It's also really handy that his shop is less than a mile from the Roush facility. After a discussion with Chris, I went back to my shop and took a "whizzer wheel" to one of the block pieces left from the research into improving the oil passages in the ordinary FE block. I cut out a sufficiency of the block skirt and took it back to Chris.
Further discussion centered on the advisability of using the Meta-Lax stress-relieving process as an adjunct to producing the finest possible repair. After listening to Chris, we reached this conclusion in this manner.
In the metro Detroit area, there are a number of steel-manufacturing concerns. The giant crucibles that hold the molten metal during the steel-making process require repair on a regular basis. It's not unusual to have to cut a 6x6-foot section out of one and weld in a patch. The wall of the crucible is 5 inches thick. Such a repair was generally good for as much as two or three months. The repair would then fail and have to be redone. The addition of the Meta-Lax process to the rebuilding effort was so successful that repairs would last as much as three years.
It's beyond the scope of this article to explore the metallurgic reasons for this improvement. In simple fashion, the improvement in grain structure, not only the weld, but also the entirety of parent metal,brings about the amelioration. I had to have it. Luckily, Chris has the necessary equipment.
Another benefit was discovered at Hi-Tech. The grinding and welding made it clear that this block has a high nickel content. Almost all blocks from Ford during the early '60s were ordinary gray iron. My sources all agree it would be unusual to have the nickel. The grinding sparks and welding ease made it clear that, at least in this case, nickel is present.