Modified Mustangs & FordsHow To Engine
Ford 390 Block Surgery
Turning a mild 390 Ford engine in to something wild
With the Meta-Lax equipment standing by, we placed the block on Chris' welding table. The legs of this structure are isolated from the floor by special rubber pads. Next, the vibratory inducer was clamped in place on the back edge of the work surface. A transducer to send information tothe control panel was attached in its turn.
When the equipment is turned on, the only sign that it's working is a faint hum, and it's noticeable that tools on the work surface tend to"walk around." The resonance of the block was ascertained from the meter readings on the control panel and the proper settings made. Once that's done, the machine does its work without assistance for about 10-15minutes. Further meter readings tell you preparation is complete. It's time to take the "rosebud" torch and begin the heating of the welding site. A resetting of the Meta-Lax machine for welding processes is necessary.
Chris has a never-ending search for improvements in welding--both in technique and materials. He's engaged in an exploration to find a better rod alloy for cast-iron welding. His partner in this exploration is one of the major rod manufacturers. The search is open-ended, and he'll havean even better answer two months from now than he does at present.
The actual welding of the patch was almost anticlimactic. He'd ground out the broken hole to a rounded-rectangular shape and traced the hole onto the piece of patch material from the other block. The shape was band-sawed and then ground until it could be urged into the hole. When hammer taps put it into position, he picked up his TIG-torch and started to weld.
After tacking it into place in several areas, he welded about a 3/8-inchspot. Next, he took a chipping hammer, modified with a rounded end instead of a point, and peened the bead he'd just formed. He jumped across to the other side of the patch and repeated the process.Crisscrossing in this fashion, he had the patch all in place withinabout 10 minutes. He repeated the entire process on the outside of thepatch. When the welding was complete, he reset the Meta-Lax andre-treated the entire work piece. When it had cooled, it was ready forthe truck to take it back to the Race Shop.
The next task was to replace the cylinder surfaces damaged when theengine came apart. When the rod broke, the piston slammed the head,instantaneously jamming up the combustion chamber surface and crackingthe water jacket into one head-bolt hole and across into one of thepipe-plugged upper openings. (I'm going to try to repair this head foranother project; our new engine will be a different configuration.) Thebig end of the rod flailed around and, in its movements, damaged thebottoms of the two closest cylinders and the bottom of one lifter silo.These holes would require sleeves.
We started by taking extensive sonic readings up and down the cylinderwalls. A trip to the catalog told us the sleeve size that would give themost strength, taking into account the necessity of having support fromthe original block. We ultimately arrived at a compromise of these twodimensions and ordered the sleeves.
Having bored the block to the correct size, the sleeves were installedin a lathe and cut to a length that would leave material standing"proud" of the deck surface after installation. These cuts also madesure the ends of the sleeves were square to the walls.
The Roush Race Shop procedure for installing a sleeve is based on theuse of liquid nitrogen as a cooling (and therefore shrinking) agent.With the block still locked into the boring machine for stability, aspecially constructed stainless steel "cooler" is filled with liquidnitrogen. The sleeves are placed in this material and left for 10minutes or more. With everything set ready, the sleeve is plucked fromthe clear liquid in the "cooler" using a pair of pliers. Now shrunken bythe cold, it is slipped into the bored block. At ambient temperature,the sleeve is an interference fit into the block. Super-cooled in thisfashion, it shrunk and will slide into place. However, it's necessary tobe prepared. On first exposure to the air, the humidity immediatelycauses a thick coat of frost to form. The first sleeve had to be nudgedinto place with a tool made for this purpose. A honing plate isimmediately torqued into place over the deck end of the sleeve withsteel straps, making sure pressure is holding the sleeve down againstthe step left at the bottom of the bored cylinder.