is it possible to weld or epoxy a crack on the outside of the block, the water in the block must have frozen and cracked the cooling passages, it is about 2 or 3 inches long and the rest of the block looks ok. If it is only the cooling passage can I clean it really good and use some JB-weld on it. this motor will only be used on the race track so it won't be exposed to the rigors of street driving.

 

Red,

First, you have to be certain that the crack is only on the outside of the jacket. If you have the case tested, you might find more than just outer cracks.

Second, the problems of usng a repaired case may not be worth the trouble. Epoxy isn't even an option. Brazing (at a minimu) or nickel welding are the only sound methods. If you have it welded or brazed, you first need to drill a hole through the case at each end of the crack to relieve any stresses on the casting. Notch the crack to allow good adhesion and fusing of the filler material. If you are brazing, you'll need to preheat the entire reapir area thoroughly to prevent localized stresses caused by hot weld on cold iron. Since the case is too large to fit in many ovens, you'll probably have to heat it with a large rosebud torch tip.

Next, braze or weld the area, then allow it to cool without quenching. You may want to reheat the area with the torch to continue to relieve stress.

Once that's done, you'll need to check the case for twist. Machine as necessary.

By the time you're done, you might be better off starting with a different case, but it is possible to successfully repair what you have if you really want to.

 

find out where the crack goes. grind it out as much as you can. i like it use a torpedo heater to raise the temp a little, only brings it to 200*F at best. weld it with steel mig and you'll get good results, but you won't be able to do much machining later. if machinability is a concern i'd use nickel tig or stick, in that order.

 

If this is purely a drag motor, couldn't you just fill it with hard blok? unless you've already done machine work or the block is rare you would probably be better off finding another one.