1933 Harley-Davidson VL Engine Case Prep & Glyptal Coating
Before the 1933 Harley-Davidson VL engine cases could go to the machine shop, the final case-prep work had to be finished: chasing threads, cleaning tapped holes, washing the cases, masking the surfaces, and coating the inside with Glyptal. This step pairs directly with the earlier VL case preparation and the internal VL baffle repair, and it also leads naturally into the cylinder and head preparation stage of the engine build.
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VL engine cases ready for final thread chasing, cleaning, and Glyptal preparation.
Chasing the Case Threads
Now that all my repairs were completed, there were just a few more things to do before the cases could be sent to the machine shop for rebuilding. I started with chasing the threads on all the tapped holes. This is easy to do, provided that you have all the different size taps available. Then it's just a matter of carefully running the tap down each hole.
Tapped holes cleaned with wire brushes after chasing the case threads.
Cleaning the Tapped Holes
Once all the threads had been chased, all the holes were cleaned with wire brushes attached to a hand drill. This removed any chips made by the tap and cleared out any remaining gunk that had built up over the years.
Engine cases cleaned in a warm soapy bath before coating the interior.
Washing the Engine Cases
Then it was off to a nice warm soapy bath and more cleaning with bristle brushes.
Cases blown dry with compressed air to complete the cleaning process.
Drying the Cases
Finally the cases were blown dry with compressed air to complete the cleaning process. Now it was time to coat the inside of the cases with Glyptal.
Preparing for Glyptal
Glyptal is an enamel-based sealer used inside engine cases to, you guessed it, seal the porous case walls to help prevent oil from leaking through. It also has the added benefit of smoothing out the castings, which keeps the oil moving around inside the case more efficiently. Of course, you don't want to get it everywhere, so I taped up all holes and outside surfaces first.
Cases taped off before applying Glyptal to the inside surfaces.
Applying and Baking the Glyptal
The Glyptal smells a bit like your old lady's nail polish, so you'll want to make sure you're painting in a well-ventilated area. I applied it to the cases with a 1" paint brush and carefully worked it into all the nooks and crannies. Once I had a good even coat, each case half was baked for two hours at 275 degrees Fahrenheit, per the manufacturer's instructions. The result was a nice smooth coat of burgundy enamel.
Finished Glyptal coating after brushing and baking the case halves.
Final Cleaning and Machine Shop Prep
Lastly, both case halves went back into the warm soapy bath for another scrub before being dried with compressed air. Then they were bolted back on the engine stand and sent off to the machine shop.