Displacement On Demand: Part 1
Displacement On Demand
Part I: Golen Engine Service Creates a Bigger and Better LT1
by Scott Parker – Photography by the Author
The LT1 engine, despite its Optispark woes, has been known in its short life to be a solid and durable engine. Even though it is merely GM’s second-generation small block V-8 with only a few improvements over its decades-old ancestors, its only known flaw is the occasional spun rod bearing. This minor imperfection is easily forgivable when you consider the years of tireless service and the abuse it suffered in the hands of greedy racers such as the readers and editors of GM High Tech Performance magazine.
Despite its loyal resiliency, these soldiers never enter retirement, as they are the last of their kind. GM ceased production of LT1s when the LS1 was introduced to F-bodies, so they must instead be reborn into the cycle of automotive samsara. For those lucky LT1s that have done well in their previous life, they are treated to a full rebuild from Golen Engine Service in Hudson, New Hampshire. At Golen, special attention is paid to minor details such as rod clearances, which helps ensure the longevity of the engine. These are one of the many lessons learned in owner Chad Golen’s 14 years of experience building engines, and 11 years with LT1s and other late model GM motors.
In addition to discovering which methods work best, Chad’s experience has also helped him to determine which materials to use. While still keeping the engine packages affordable, Golen manages to use the most durable of materials and the utmost precision to ensure their proper operation.
Ranging from $2,300 to $3,500 for short blocks and $3,400 on up for long blocks Golen Engine Service provides a wide range of LT1 and LT4 packages. The biggest difference between the packages is the displacement and the rotating assembly. The mildest of Golen’s LT1 packages, which maintains the stock displacement of 350 cubic inches, uses a performance ground stock crankshaft, shotpeened GM forged steel rods, Speed Pro Hypereutectic pistons and Plasma-Moly rings. At the other end of the spectrum are the competition packages, which use Eagle or Callies forged cranks increasing displacement to either 383 or 396ci, as well as SRP forged pistons and Eagle forged connecting rods depending on the application. These packages are designed for the extreme stresses of racing and high boost from blowers, turbos or nitrous.
The specimen for our discussion is a 383 LT1 package with optional SRP forged pistons, an Eagle 4340 forged steel crank, and Eagle forged connecting rods. Normally when mated to a set of ported LT1 heads and a .510-inch lift cam, the package is good for over 400 horsepower. However, with an optional .522/.543-inch lift cam these gures should be slightly more robust. In any case, with the upgraded components its new owner should see a lifetime of miles on street and the strip. Follow along with part I of our LT1 buildup, which will create a short-block from all of these hard parts.
|The boring is done automatically on Rottler Boring Bar to .026 over, allowing 3 thousandths for honing. This will increase the factory 4-inch bore to 4.030 when it is finished. This is one of the few pieces in Golen’s new stateof-the-art, 1,500-square-foot facility that is not made by either Sunnen or Serdi.|
|A machinist level and gauge are used to get the block within .002 before decking and resurfacing commences. Golen’s decking machine uses a Windeld tray and a CBN cutter, which makes the job go by rather quickly and creates an excellent finish. For our LT1 there will be zero decking, meaning that 13 thousandths will be taken off to match the SRP pistons. Passes are made progressively slower to make the surface as smooth as possible. Machinist George Connoly says, Since LT1s have not been around too long, they are less likely to have been worked on before, allowing a great deal of consistency with the block.|
To add strength to the bottom end Golen converts all LT1s from a two bolt to a four bolt main motor. This requires that holes must be drilled into the block to accept the ARP studs. Once the surface of the main is cleaned off and the block is set into place, so are the new caps. The two 7/16s studs are tightened down on either side to keep them from moving while acting as a guide for punching and drilling to start the new holes. As drilling begins the location of each of the holes is written on the surface of the block using a Sharpie starting from the right, near corner as point zero. This ensures consistency when the caps are removed and the holes are redrilled using a larger U bit to near 7/16s. Next, the tops of the holes are counterbored using an even larger drill bit to relieve stress risers on the tops of the main bolts. Lastly, the holes are tapped using a 7/16s tap with a size 13-thread pitch.
A fitting element is used to determine the top guide shoes for the honing machine. Once the width is set and the shaft centered, the stroke is set for the LT1 block. Honing begins with a 180-grit, which will remove two to three thousandths of material that is swept away by the honing oil. The stones must be frequently taken off and rubbed together to ensure an even hone. This process is done entirely by feel, and must be periodically checked using a dial bore gauge to ensure that the cylinders are even. Once enough material has been removed, a 280-grit fine hone is used to give the cylinders a smooth crosshatch, and then brushes are used for the finishing touch.
Honing the lifter bore can be a very important and often overlooked step. It becomes increasingly important with flat tappet cams, which will otherwise wipe out the lifter since it spins (as opposed to just moving up and down).