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the main-bearing saddle, and freeze cracks in the pan rail. Neither of these last two conditions are repairable, and this is the best time to receive the bad news. The water-jacketing should be subjected to a pressure test, at 35 psi using a soapy water solution, even if there is no damage visible; this is the only practical way to detect cracks in the exhaust runners, and it will also reveal unseen cracks in the cam valley. While there's nothing to be done about cracks in the exhaust runners, other than discard the block in favor of a good one, cracks that are accessible in the cam valley can be repaired with high-strength, high-temperature epoxy, followed by another pressure test to verify the effectiveness of the repair. Once magnaflux and pressure testing have shown the block to be sound enough to use, and before any repairs are made, it should be acid dipped to remove rust and hard deposits from the water jacketing. This step, which may take several days depending on the condition of the block, also loosens casting sand that's been trapped in the block since it was new. Services such as Redi-Strip perform this work for about $150. The block is next sonic tested to check the thickness of the cylinder walls. Recordings are made at four locations around the circumference of each cylinder, at three levels - top, middle, and bottom - and a "map" developed that allows the builder to "look" inside the casting. Sonic testing quickly uncovers problems such as cylinder walls that are too thin, or core shifts that compromise the stiffness the block. At this stage, with the declared useable, and before any repairs (other than welding) are made, Dave paints the inside of the block with Glyptol to seal porosity and any casting sand trapped on the surface that could become dislodged and find its way into the lubrication system. Glyptol is a dielectric paint used to coat armature windings in generators and starters. It has an oil base so it's compatible with engine oil. Its slick finish also speeds up oil drain-back to the sump, making it a perennial favorite with race engine builders.

A resleeved block is readied for boring. In this case, sleeving helped Dave to salvage a great deal of expensive hand work in this race motor casting.

Magnaflux inxpection is done early in the process to determine if a block is worthy of the work to follow as well as the repairability of routine stress cracking.

Repairs

Many blocks exhibiting crack damage can be saved using one or more of several methods - epoxy patching, pinning, or welding - depending on the nature and location of the damage. Some blocks are beyond help, however, particularly when they are cracked along the pan rail, or have multiple adjacent imploded cylinders, both conditions resulting from being stored horizontally, in freezing temperatures, with water in the jackets. Ironically, all that's required to avoid this type of damage is to store a block on end or upside down so all the water will drain out. In low-pressure areas like the water jacketing in the cam valley where maximum pressure is not like to exceed@ 15-20 psi, repairs with high-strength, high-temperature epoxy work well. This type of repair won't work in a high-pressure area, however, such as the cylinders where the pressure is 600-800 psi. When a deck crack runs down into the cylinder, the prescribed repair is to first sleeve the cylinder, then pin it with overlapping pins, installed in the sleeve-to-block junction and on into the valve seat. The cylinder is then bored and the valve seat cut and a new seat installed. (Sleeving, to repair damaged cylinders, should not be done to adjacent cylinders, says Dave, because the sleeves are incapable of stabilizing the deck, and a pair of them side-by-side is an invitation to trouble.) If a crack proceeds down into valve pocket and port, it can’t be effectively pinned because there isn't enough material in the port to hold the pins. In this case, the crack must be repaired by welding. A popular method for welding cast iron, one that involves progressive welding and peening, simply won't work on these blocks because they are very dirty castings. Instead, they must be heated in an oven to a glowing red state - 750-800 deg F and then gas welded