By Freddie Heaney:
Rare casting repairs: Five-step process in restoring vintage blocks to race-ready condition
Each winter frozen coolant causes severe damage to hundreds of racing engine blocks in the northern hemisphere. Though troubling, its effects are usually even more concerning when frost damage strikes a rare, historic racing block. However conscientious you are the misfortune can happen, but if it does don’t be too dismayed for the problem is not insoluble.
In Chatham, Virginia, there is a well-established engineering firm, Virkler & Bartlett, who possesses a knack for returning severely damaged engine blocks, often considered unserviceable, to race-ready condition.
Their most common candidates are vintage blocks like this Maserati example damaged by frozen coolant. Here is their five-step repair process:
1. Inspect to determine mechanical and dimensional condition. This includes examining deck angles, deck squareness to main bore centerline, main bore alignment and other critical dimensions.
2. Find crack locations using Magnaflux or dye penetrants and determine repair strategy. Welding repairs work well in some applications, but V&B prefer steel or aluminum pins with special barbed threads that pull cracks together for most castings. Pin repairs have the advantage of not distorting the casting. As a result, ridged fixtures are unnecessary and re-machine work is kept to a minimum.
Pins are installed with anaerobic sealants to lock them in place and prevent leaks. Sometimes it is necessary to machine away a portion of the damaged metal and replace it with an insert that is pinned in place. Pins are stronger than the casting and V&B has successfully pinned cracked main bore housings on highly stressed race engines.
3. Re-inspect the repaired casting to verify critical dimensions and complete necessary machine work.
Available in a range of lengths and diameters, these pins have a barbed thread that creates drawing pressure that actually pulls the sides of a crack together. They come in heat treated steel or 2024 T4 aluminum and are far stronger than the casting material. Pins are installed overlapping each other along a crack. If additional strength is required, dog-bone shaped locks can be installed across the crack using a fixturing tool to drill the requisite hole.
5. Stipple repaired areas to apply a cast finish. Repairs are invisible.
To view the drawings of the Maserati block repair
Source
V&B Engines
Virkler & Bartlett LLC
1975 Slatesville Rd
Chatham VA 24531
(434) 432-4409
www.VBengines.com
Email:rgbartlett@vbengines.com
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