Black Shadow engine painting

[craig]

I find there is no over spray or brush slop inside the Shadow covers or inside the engine split joints. Masking the engine with tape and paper is something a modern shop might do, but i dont think a production shop in 1950, making no money, would extend labor to do so. But please prove me wrong. Where is photo of Vincent engine painting?

I would have thought, maybe logically I hope, that the parts would have been painted separately. If you painted the engine as an assembly then you would overpaint all joins.My experience is that if you did this,then on dismantling the joins gets ruined by ragged edges where paint gets broken..John

 

[craig]

here is a 1948 period photo

 

[davidd]

I think the photo makes the point perfectly, that is there is no standard. I know the first production Black Shadow has painted plates and subsequent ones have plated plates or painted plates.

Regarding the numbers, it is likely that the serial number was the last number stamped on the bike, but the prefix may have been stamped on earlier. I have seen two engines with no "F10/AB/1/" and only the serial number. The prefix is not there and the number is stamped so a prefix would not fit (so it was not ground off and it matches the mating number.) Unless you have perfectly detailed photos of the bike in its original condition, restoring it to original is a fiction, albeit a small one. I think it is worthwhile and interesting to ask these questions, but drawing conclusions about uniformity of many details is not much more than a guess.

I have never seen any photos of the painting operation associated with Shadows.

David

 

[greg brillus]

Regards to the painting of Shadow engines.....David Bowen told me that the case halves were bolted together with a few through bolts and cover plates screwed on over the timing, primary, cylinder spiggot holes, etc. other fittings and holes blanked off. Then the cases were lowered into a drum of black stove enamel, then left for a short period to drip off excess paint and then hung in a cabinet of some sort with a gas ring at the bottom to heat the cabinet and aid in the stoving of the paint. I think the heads and barrels were done in a similar way, but maybe with a different paint due to the heat these items would have to endure. I do not believe the parts were primed, rather the cases were etched using a solution they had available back then ( pylumenising) or whatever it was called. This would be a similar process as is used today on alloy aircraft sheet metal and other components which gives the surface a slight gold finish. It is more of a barrier to corrosion than anything. But the original finish would have been very thin, and yes the last part of the engine number was stamped on after painting, and the numbers touched up with a fine artists brush afterwards. I am unsure how the factory painted the outer covers, but i would have thought that they would have sprayed them to get a descent enough finish. It is a fair comment to say that almost all Shadows restored these days have a paint finish far more shiny and much thicker than the factory produced....well not to many folks have a spair drum of "Pinchin Johnsons" finest stove enamel kicking around in their sheds, do they......any thoughts.......Greg.

 

[Albervin]

I would have expected David Bowen to have jumped into this thread as he was there.

 

[craig]

I understand that this photo depicts the first Shadow on line with plated plates. I agree that the the Ted Davis photos of the first Shadow show black plates, drooping HRD tank logos and an unpainted 5" speedo can.

 

[craig]

Thanks Greg, I have heard of this "dipping process" before, and certainly i can see evidence of it on small parts like engine plates, brake plates, Girdraulic parts and the like. But i cant seem to understand how it would work with a set of cases...not only the masking but making the cases liquid tight for even partial submersion.......... i see not one drop of black paint squeezing thru on any of the shadow engine pieces. I feel we do not fully understand or appreciate this 1948 process. I have heard of paint floating on a bed of water and as you submerge the part and bring it up level , it adheres to the upper surface only. Maybe this "float" was part of the process? I just dont see masking and submerging engine parts as cost effective production practice.
What I can envision is "hand slathering" paint on pieces, rather than submersion, but what do I know.................we need help on this
But rather than get hung up on the process it self, i want to know what was masked and what was not masked to know how to cosmetically restore an old Shadow.
For instance, the timing cover does not appear to be masked at any of the external gasket surfaces like oil quill, oil filter, oil jet, mag hole...........but the large inside case gasket surface is no paint, no drips , perfect
Same with primary cases.
But the engine cases are much more complex and I would like a much more detailed understanding.
Thank you for helping with this
Craig

Regards to the painting of Shadow engines.....David Bowen told me that the case halves were bolted together with a few through bolts and cover plates screwed on over the timing, primary, cylinder spiggot holes, etc. other fittings and holes blanked off. Then the cases were lowered into a drum of black stove enamel, then left for a short period to drip off excess paint and then hung in a cabinet of some sort with a gas ring at the bottom to heat the cabinet and aid in the stoving of the paint. I think the heads and barrels were done in a similar way, but maybe with a different paint due to the heat these items would have to endure. I do not believe the parts were primed, rather the cases were etched using a solution they had available back then ( pylumenising) or whatever it was called. This would be a similar process as is used today on alloy aircraft sheet metal and other components which gives the surface a slight gold finish. It is more of a barrier to corrosion than anything. But the original finish would have been very thin, and yes the last part of the engine number was stamped on after painting, and the numbers touched up with a fine artists brush afterwards. I am unsure how the factory painted the outer covers, but i would have thought that they would have sprayed them to get a descent enough finish. It is a fair comment to say that almost all Shadows restored these days have a paint finish far more shiny and much thicker than the factory produced....well not to many folks have a spair drum of "Pinchin Johnsons" finest stove enamel kicking around in their sheds, do they......any thoughts.......Greg.

 

[chstorm]

When rebuilding my Shadow C-series engine, we decided to use ceramic coating on cylinders and cylinder heads, a coating which will stand very high temperatures. The result was very good and can be recommended. The work was done by Camcoat Performance Coatings, Hoyle St, Warrington, Cheshire WA5 0LP. Tel.: 01925 445003 or 01925-445688

mailto:web@camcoat.com

​

 

[Magnetoman]

But the engine cases are much more complex and I would like a much more detailed understanding.

Me too. I'm not sure we're much closer to the answer to the question you posed. The pyralumin process required dipping the components in a fairly hot solution for several minutes, making it very unlikely they were masked in any way, although it doesn't eliminate them having been loosely assembled (but, with the heads done separately). However, if the engine had been assembled with blanking plates screwed on everywhere to keep paint from coating the inside (consistent with there not being paint on the inside), the engine would have floated on the vat of paint. I don't have my engine handy to measure, but the internal volume certainly must be at least 1 cu.ft. Assuming paint has a density of ~60 lbs/cu.ft. that's a lot of buoyancy to overcome. Hence, it seems pretty unlikely the cases were bolted together and dipped into a vat of stove enamel.

 

[Hugo Myatt]

Page 364 Phil Irving's autobiography gives a clue.