Over the winter, I’ve made a lot of progress on my 1933 Harley-Davidson build. Now that the engine has been sent to the machine shop for rebuilding, I wanted to take some time and write about what it took to get the engine ready to be rebuilt. If I had to sum it all up with one picture, it would definitely be this one of me standing at the blasting cabinet. Almost every part had to be cleaned with fine aluminum oxide media to remove 80+ years of dirt and grime.
I’m going to begin with the cylinder heads and work my way down through the rest of the engine. On a flathead engine, the valves are located in the cylinders, so there are no moving parts in the cylinder heads. The heads simply bolt to the top the cylinders, hold the sparkplugs and provide a combustion chamber. The main problem you run into with VL heads is that the cooling fins are often broken from improper removal of the headbolts. My heads only had a few broken fins, so I chose to “massage” the broken fins with a grinding wheel to get rid of the jagged broken edges. This cleans up the heads visually and you’ll hardly notice the missing fins once everything is painted and installed. For more serious damage, I’d recommend contacting Tom Faber to have your fins replaced. You can see examples of his top notch work at the Harley-Davidson Museum in Milwaukee, which is one hell of a reference!
Moving down to the cylinders, I was lucky enough to find a set without any broken fins and close to a stock bore. My cylinders had been bored once already, but that only brought them out to .005″ and .010″ from stock. All that was needed to prep them was some time in the blasting cabinet to clean off the old paint and a fresh coat of aircraft primer. The cylinder heads received the same treatment, leaving me with a set of clean green cylinders and heads.
The real work began when I started on the engine cases. First there was a general cleaning using lacquer thinner before moving onto a couple hours of more aggressive cleaning in the blasting cabinet. Then the cases were carefully inspected for damage during which a hole was found in the right front engine baffle which needed to be repaired.
This proved to be a time consuming repair as a number of custom tools had to be built to complete the job. To start, a piece of copper plate was fabricated to cover the hole and clamped into place. Copper doesn’t easily weld to aluminum, so with the copper plate covering the hole, I could TIG weld a new bead right across it. Then the numerous cracks which spread from the hole were each welded up. The removal of all the excess weld material required another custom tool and a hand held router. I started with a standard 1/2″ four-flute end mill and made an aluminum sleeve to cover the cutting surfaces on the sides of the end mill. This kept the end mill from cutting into the sides of the case, but left the bottom of the end mill exposed to cut away the excess weld. I made slow passes across the baffle, lowering the end mill 1/32″ each pass until I reached the desired height. I did this with the cases bolted together, which allowed me to measure the finished heights from the intact left side baffle.
With the cases repaired, I moved onto chasing all the threads in the various tapped holes before doing a really thorough cleaning. All that welding, grinding and tapping, along with being cleaned in a blasting cabinet meant there was potential debris hidden in every nook a cranny of those cases. Every hole was cleaned with wire brushes and blown out with compressed air, before the entire case was submersed in warm soapy water and scrubbed with bristle brushes. This was followed by more compressed air and another scrub/soak.
The last step was to coat the inside of the cases with a sealant called Glyptal. All the surfaces that I wanted to remain clean were taped off and then a nice smooth coat of Glyptal was applied with a brush. After a two hour bake, the inside of the cases were smooth and sealed.
A good portion of my internal engine parts are being replaced with new parts from Eastern Motorcycle Parts, so things like valves, springs, pistons, shafts, etc will all be new. That still left the cams, tappet blocks, flywheels and connecting rods which needed to be cleaned and repaired. All of these parts were placed in the blasting cabinet to be cleaned up. For the tappet blocks, flywheels and connecting rods, that was all that needed to be done and they were gone over with a wire brush before being washed with lacquer thinner and placed to the side. The cams needed a little more work since the #4 cam had broken threads on the worm gear with drives the oil pump.
Since these were a matched set of cams, I didn’t want to just replace the broken cam, but instead used another #4 cam as a parts donor. V-series cams are not made from a single piece of stock, but instead are made in two parts. One part being the shaft and the other the drive gears and lobes. These are just pressed together, so to repair my cam I just needed to press out the shaft with the damaged threads and press in the donor shaft.
The last major component to tackle was the cam cover. The oil pumps and the timer are mounted on the cam cover, so all of these had to be removed and disassembled before cleaning could begin. The cam cover was by far the dirtiest piece and took a bit of scrubbing with lacquer thinner just to get it clean enough to go in the blasting cabinet.
Like all the other parts, a trip through the blast cabinet followed by going over the parts with a wire wheel made them look good as new. After many hours of cleaning and repairing, all the pieces were ready. Now it’s on to the transmission!
For more in depth articles on this project, check out Riding Vintage.