Gray Marine has an interesting past going back to its origin as the Gray Motor Company in 1906. From that time until it’s final sale in 1968 it had produced hundreds of models from 3hp, two cycle, engines to a straight 8 175hp, it’s largest gasoline engine. Gray was also responsible for perfecting the venerable, still in use today, 6-71 diesel now produced by Detroit Diesel.
Rebuilding a Gray 6 is not an uncommon occurrence for us but when Gary Hutchens, of Torch Lake Classics, delivered this 6-140 to our shop it was obvious this was not a common piece. The immediate detail leading us to this conclusion was the name/ID plate, in black and red, proclaiming it to be a Garwood/Gray6-140. Designed and built for the prestigious Gar Wood by Gray Marine.
The semi-exposed rounded cylinders on the port side were a dead give away to its advanced age, which dated it to 1939. Built on a 244 CID continental base, this engine was one of the most powerful “High-Speed” engines Gray offered at the time. Only “racing” engines and the straight 8 at 175hp was larger. The 244 are, as most Gray’s are, a single ported engine. This engine was fitted with a pair of Stromberg SFM-3 carburetors. With a weight of only 620 pounds it represented serious power in a relatively light package.
At Custom Marine and Machine each of our projects begins with a series of photos, front, back, sides, top and close ups of all details we will need to “remember” on final assembly. We also record paint color and other details. At this point I pulled a wadded up bunch of newspaper from the exhaust outlet dated August 1970.
During tear down it was determined that, though warn from use, the long storage period had done most of the damage to the internal parts. The oil left in the crankcase had evaporated to a thick black mess, much like road tar used to repair cracks in the expressway. After thorough cleaning the inspection process began. A typical flat head 6 cylinder has more than 650 individual parts, not including, nut, bolts, washers and gaskets. At our shop all of these parts are cleaned and inspected and nearly half are either reconditioned or replaced.
With this particular block, partly because of the age, we decided complete sleeving of all cylinders to be the prudent course of action. The pistons were in surprisingly good condition so they were cleaned, dye checked for cracks and measured. With only small differences in diameter we decided to selectively hone each cylinder to its piston and reuse them. I did do a few things to the pistons including boring and honing for a larger wrist pin and changing the method of keeping the full floating pin centered. The original system consisted of aluminum “buttons” installed in the ends of the pin that were allowed to “bounce” off the cylinder walls. I thought grooving the pin bosses and installing spinolox retainers to be a much better system. This is an example of improving an existing system with modern technologies, which I try to do as much as possible.
The crankshaft, which was not only worn but also bent by .008 to .009 of an inch, was straightened and reground to provide new bearing surfaces. The camshaft was also checked and reprofiled to eliminate any lobe wear. After resizing the big ends of the connecting rods came the task of repouring and precision boring the main bearings.
The process of rebabbitting bearings is about 2/3 science and 1/3 art and is something we do on most of the pre-war engines. Although time consuming and fairly expensive, rebabbitting allows you to match the bearings to the crank so you don’t have to rely on existing supplies of bearings or in many cases now days no bearings at all.
While the block and various other pieces were being thermally cleaned and shot blasted the accessories were reconditioned. Oil, fuel and water pump, starter, generator, distributor and reverse gear were all done. Many of the accessories require fabrication of various parts no longer available.
When the block came back from being cleaned it was checked for cracks, bored, sleeved and honed. We always install new hardened exhaust valve seat, for unleaded fuel use, and new valve guides which are precision reamed to fit the valve stems correctly. Main bearings were set in the block and align bored to provide an absolutely straight and parallel crank bed and proper oil clearance. After all machine work was completed the engine was given a bath of soap and hot water, dried and final assembly started.
On this particular engine we ran into a few snags one being the Stromberg carburetors. Stromberg’s were the most sophisticated and probably the most efficient for their time but poor storage made these carburetors look like they had been lifted from the bottom of Lake Michigan. With carburetor kits for Stromberg’s at $475.00 each and given the poor condition of this pair we decided to go with a matched pair of more economical and readily available Zeniths. This swap required some engineering and linkage fabrication.
As we neared completion I was able to speak with Rich Gaugler the owner of this unique engine and he related the story behind it. His Great Grandmother had purchased the 19’ Garwood runabout and engine for his father new in 1939. According to Tony Mollica, Garwood sold only 25 19’ runabouts in 1939 and only four were ordered with the 6-140 engine!
This kind of power in a 19’ boat is a good example of the more custom and performance oriented builders of the period. In contrast, an 85hp or 95hp K model would probably have powered a similar sized Chris Craft.
After painting, some detailing including restoration of the ID tag, and final assembly, we fired the engine and put some five to six hours of run time before final delivery. As the engine sat there idling flawlessly I remember the wide smile on Rich’s face and his comment that the sound of this old flat head, that had not run for over 30 years, took him back to when he was 10 years old.
Provided with proper maintenance,
repair and sensible use this Garwood boat and engine will likely last through
Rich’s lifetime and be available to his heirs as well. Many times our interest
in classic boats runs much deeper than a collection of varnished planks
and nuts and bolts, the very sound of a classic inboard or the feel of
a woody cutting through the water can evoke memories and feelings of another
time in our lives.