Tag Archiv: lock&stitch

Lock & Stitch Part 2

Having received all the necessary tools and supplies from Lock-N-Stitch in Turlock, California, we could begin the process of repairing our Jaguar 4.2 block. The company provides an informative DVD that explains all the steps and options which is essential. The basic idea is to replace the crack with a linear line of screws and begins with a single drill hole that will is placed well beyond the crack to ensure strength.

The above photos show the Lock-n-Stitch spacer which inserts into the first drill hole and lines up the drill bit for the next cut. The tool isn’t completely necessary, but it organizes the holes neatly and ensures proper distances between screws. For the first run, only every second screw is inserted. The holes are then countersunk with a spot face bit that will cut a controlled shoulder for the screws. The spot face distance is critical and depends on the wall thickness and thread distance.

The first set of cascading drill holes are then threaded and the pins/screws are inserted permanently into the block with thread sealant. The screw is simply wound into the block until the breakaway head shears off. The remaining stubs are then ground down so the gaps inbetween the screws can now be filled with the second series of screws. The following picture shows the second line of pins being inserted with the breakaway top of a single screw resting on the block.

After the complete line is finished a needle scaler was used to replicate the rough finish of the block. The end of the screws were left slightly protruding to retain as much strength as possible. The following picture shows the needle scaler and a finished line which was pressure tested to 10psi for leaks.

Since no bubbles were visible from the pressure test we can now begin assembly of the 4.2 engine from the bottom up. Below is Lock-N-Stitch’s own promo video for their product.