Replacing Cracked Block/Head

If my all-original TO 30 has a cracked head, where can I get a rebuilt or new one?  August 3, 2016.

Yes, the Z series engines, Z120 and Z129 in particular tend to crack in the webs between the cylinders. When this occurs on the top it is not a major problem, and can be sealed with a new head gasket sprayed with Copper Coat, and properly torqued to factory specifications.

The wet sleeves are also supposed to project slightly above the top of the block to properly seal. Continental used to make a shim kit to raise the sleeves to the proper dimension. Sadly those kits are no longer available. Other options include milling the top of the head a bit or making your own shims.

The Standard Motors engine used in the TEA-20 has a similar problem, and they raise the sleeves by placing a circle of copper wire under the lip of the sleeve. I’ve never tried that on a Continental engine. Other possibilities are improper installation of the O-rings on the sleeves, or damaging them during installation.

If the block is cracked between the bottom webs the cracks usually extend into the main bearing mounts. Repairs to the bottom cracks can include “bolting”, welding, and stitching. There is also the option of sending the block to a rebuilder, or purchasing a rebuilt block, and sending your old block in as a core. There is a salvage yard in the Batavia New York area that specializes in this type of repair.

Short blocks can be purchased through Valu Built Tractor Parts or Tractor Supply Company. There may be other sources as well. Used blocks also show up at salvage yards and on ebay. I believe there was at least one block for sale on ebay last week but it has apparently been sold. If you do buy a used block, do not scrap your old one, you should be able to sell it as a rebuildable core. Rebuilt short blocks which include a new or reground crank, new pistons and sleeves, rebuilt rods and all new rod and main bearings were selling for around $1000. When you consider the cost of parts, and labor to rebuild an engine the price is not that bad.

As for the cylinder head, yes they can crack, and cause leaks. Rebuilt cylinder heads are available from the above sources as well as Chapin Cylinder Head Service. A engine rebuilder can magnaflux your head to determine if it is cracked. They can also magnaflux your block. Rebuilt heads usually are sold with new, or reconditioned valves.