LOCK-N-STITCH® Repairs the Original 427

LOCK-N-STITCH® Does Their Magic On The Original 427...
In March 2009 the original (numbers matching) 427 decided to toss the #2 rod cap through the pan so I replaced it with a ZZ454 and decided to save the original drive train.  I took the original 427 block to Swanner Racing in Wild Peach (TX) where Bernie Brown hot-tanked it and checked the bottom end for cracks.  No cracks were found so it looked like the only major damage was the hole in the cam gallery caused by the #2 rod.  It turns out that there is a place in California called LOCK-N-STITCH® that says they have fixed many big-block Chevy's with the same failure so in September 2010, I took the 427 to them to see what they could do.

Gary Reed, the CEO of LOCK-N-STITCH® has been in this business for over 40 years.  He has developed several methods of repairing cast materials including furnace brazing, metal fusion processes and his trademark, the LOCK-N-STITCH® pins.  It was the pin method they elected to use on my block.  The pins are depicted in the logo above.  The pins are manufactured with a shear section below the head.  The part to be repaired in drilled and tapped with a special tap and the pin is inserted.  Then it is torqued until the head shears off.  They continue installing pins until the entire crack is filled with overlapping pins.  After all the pins are inserted, the pins are peened down and the surface is finished to look just like the original material..

After checking it out thoroughly, they decided it was a relatively easy repair and Alaa got started on the work.  He first ground the sides of the hole in the block so it was smooth and straight.  Then he fabricated a steel patch that snugly fit the hole.  Steel was used so the thermal coefficient of expansion would be the same as the cast iron.  Next, the patch was glued into place with a special proprietary glue and the pinning process was started with two pins opposite each other.  Then 2 more were installed 90 degrees from the original two and so on until the entire perimeter of the hole was filled with overlapping pins.

After all the pins were installed, the surface is worked until it blends in perfectly with the original surface.  Then head plates are installed and the freeze plug holes are blocked and the block is pressure tested to 20 PSI to assure a leak-free repair.  After that, the surface is cleaned and the repair is complete.

The work these guys do borders on magic if you ask me.  They tell me the repair is stronger than the original block.  They chose the stitch method on my block because if they furnace brazed it, it would have been heated to 900-1000 degrees and the resulting warpage would have required align boring of the main saddles and well as the cam and probably decking of the head surfaces.  Since the whole purpose of this repair was to save the original numbers on the right head surface, that would have complicated use of this block.  As it is, this block can simply be cleaned and assembly can begin.

Alaa and Gary told me they had done a number of this exact repair.  In fact, Alaa said that although they had never done it, if necessary, they could cut a block IN HALF, do a repair and then put it back together again.  See what I mean about magic?  They also said this was a comparatively little job.  Not very little to me but in terms of the kind of stuff they do, the cylinder head on the left was sitting there for repairs when I got there.  Notice the tape measure I placed on the head to give perspective.  The end of the tape is 15 inches from where the tape measure is sitting.  The valves are about 12 inches in diameter!  The valve stems were about 3 inches in diameter.

As an example of their other kind of repair processes, here is a Packard block that the side was rotted out of from the cooling jacket being filled with water and no rust inhibitors.  They fabricated a new steel panel and furnace brazed it into place in the side of the block.  They also had to do a few thread repairs on this one.  Alaa told me that if a panel they need to replace has casting numbers on it, they will duplicate the exact numbers on the replacement panel so after painting, it looks completely original.  Amazing stuff.

My thanks to the guys at LOCK-N-STITCH® for saving my numbers matching block so that some day, it can live again in the 1967 Corvette it came from the factory in.