Hispano-Suiza 8F (Part 11)

I’ve finally got there. One post more than I thought I’d need, but the two engines are finally complete and a selection of photographs of them added to the galleries under the drop down menus at the top of the page.

There wasn’t much left to finish them really. The main activity required was the completion of the coolant hoses, and the installation of the exhaust studs.

As before the hoses were made up of three parts.

  • A wire core to make sure they keep the right shape during heating.
  • A polystyrene  inner tube to give them the right diameter.
  • An outer sheath of black heat shrink tubing to give a true rubber appearance and thin wall thickness at the ends.
The black tube on the right of the picture is there to form the flared end on the coolant hoses, and is the same diameter as the lugs on the model. It was removed from the formed hose once the heat shrink tube had been shrunk to size.


Each hose was run to the model then measured up. A final version was then made from fresh materials, as I’ve found it is necessary to partially shrink the outer onto the assembly then bend it to shape.  Once that’s complete you can remove any wrinkles in the outer by completing the shrinking operation. If you try to slide the heat shrink over a bent inner, like the one in the picture below, the inner wall of the curve wrinkles to an extent that can’t be remove entirely during the heat shrinking process.

Running a dummy hose to the model prior to making the final version.

The process is a bit laborious to be honest and caused me quite a bit of grief. In hindsight it would’ve been a much simpler option if I’d done it in conjunction with fitting the exhausts rather than after. As it was some choice epithets might have been uttered during the operation.

The hoses on the burgundy engine were by far the worst to do as the arrangement is more complex than on the black one because of the location of the water pump.

Other minor work included fitting the cylinder priming pipework on the top of the burgundy engine. For some reason this was quite difficult, which was a surprise as it was relatively straightforward on the black one and they are supposedly identical. Probably just an off day at the modelling desk.

The unfinished left hand end on the priming pipework will be completed once the engine is installed in the ‘Miss Severn’ model.


The coolant hoses also required the making of several batches of faux jubilee clips. These are fairly simple but take time. An appropriately sized tube is cut into thin sections and some thin (0.8mm OD) tube soldered to the rim. The whole assemble is bright nickel plated. As a final flourish a brass pin which has had its head slotted and then been bright nickel plated is glued into the cross tube to look like the screw mechanism.

The very last operation was to add the exhaust mounting studs. These are just glued on and have no physical function. They were made from Some M1 threaded rod with M1.0 brass nuts glued in place. The whole affair was then burnished to make them dark. Tedious and unexciting work. 32 required per engine.

If I were make another of these models I’d approach the exhausts in quite a different way I think. I’d keep the flanges separate from the  exhausts themselves, which I have seen on some engines. That would make getting everything aligned much, much easier and would allow the studs to be actually glued into the block.

That’s it for these engines then. A lot of fun to make, but much more involved than I thought it would be. I’d secretly envisaged it taking about half the time it has. I wasted a lot of time and effort though trying to master white metal casting of the aluminium parts before admitting defeat and using the cold casting technique. Now that I know what I’m doing and have all of the moulds to hand I think I could build another engine in 250 – 300 hours. I might even do that as I’d like to have an unmodified aviation version too. They’re not cheap though when you add up the costs of all the nuts and bolts.

Here are some pictures of the finished models. There are a few more in the gallery pages too.

There is a CAD version of the aviation engine ready to go. I just need to get the exhausts printed off…


Hispano-Suiza 8F (Part 10)

I had hoped that this would be the last post on the building of these engines, but they will not lie down and give in. The exhausts in particular have been giving me grief.

Given how large they are, and the visual impact of that, I wanted them to have a real metal feel to them. I didn’t think I’d be able to achieve that with painting, and hence decided to build them out of copper and brass (see previous post). They’ve turned out to be some of the most complex soldered items I’ve ever made, but I got there in the end.

Below are the basic items for the burgundy engine which will be going in the Miss Severn type model. They are complete and copper plated, but do not have the inlet and outlet water cooling pipes fitted.

I’m aware that a lot of my pictures show things after they’ve been cleaned up, so here is a picture of one of the exhausts during assembly.

And after clean up, but before plating.

I wanted to plate them to give a homogenous copper look. I have seen welded copper exhausts on one restored boat from this era so, if designed correctly, they must be able to withstand the heat. I doubt brass ever would though, so my headers needed hiding under copper plate. For the doubters, remember they are bolted to an aluminium casting so if your heat management is right, they must be able to work. Aluminium melts about 400°C  (750°F) before copper after all.

After plating with copper I wanted to give them an aged rather than a new polished look. I hit YouTube and tried a number of techniques found there.

I don’t know why, possibly because of the ‘brighteners’ in the copper plating solution, but Sodium Bicarbonate had zero impact. I even left the samples on a radiator overnight in a jar with bicarb solution in the bottom, but they were all still lovely and shiny the morning after. Acetic and citric acids were also tested (OK, vinegar and lemon juice to you) but didn’t really deliver. Immersion in an ammonia solution was exactly the opposite and just way too much. Verdigris all over the place in a very short time. Using burnishing solution worked quite nicely, but gave a blue/black patina, not the brown I was after.

Copper pipe naturally aged by leaving it, lonely and unloved, in my garage for 25 years vs the one on the right ‘aged’ in burnishing fluid.

In the end I found hanging the copper items in an ammonia vapour bath was the best option. You need to make absolutely sure you don’t get any of the neat ammonia solution on the samples though, as that leads to verdigris spots.

That all sounds quite technical and posh, but the reality was a 5L plastic can with a cup full of ammonia solution (34% by vol) in the bottom. The parts were hung off the rim on wires with the top popped back on to limit evaporation. I left the parts in there for about 2 hours, but the temperature in my garage was about 5°C  (41°F) at the time. I doubt they’d need that long in summer.

Having proved the method on some samples, I put the black engine’s exhausts in to treat them. It was a disaster… I’m not sure what happened, but the copper plate started to flake off all over when I removed them. Something must’ve contaminated the surface prior to plating, but I’ve no real idea what. Perhaps my acetone had something in it or the cleaning brush did.

Ho hum…

Whatever, I had an enjoyable afternoon removing all of the copper plate and cleaning up to start again from scratch. Thankfully that went without any further problems.

The burgundy engine has a slightly different and more complex cooling arrangement to the black one, primarily because of the alternative ‘distributor’ rear end arrangement. That required some pipes to feed the water jacket from the pump.

I tried making them from tube, but couldn’t get the tight radius bends I wanted without the tube collapsing. In the end I made them out of solid 4mm rod. Say nothing and no one will know!

Water jacket feed pipes.

Some before and after pictures of the soldering ops.

Risky stuff, as I only used one type of solder, so there was a very real risk of unsoldering old parts while I was adding the new ones.

(I mainly use a cook’s blowtorch for my soldering).

The end result after clean up and a couple of hours in the ammonia vapour bath. The steel spigots are there to mount the exhaust to the engine. The ‘mounting’ bolts will just be for show. The small water outlet at this end of the picture is actually a cold cast bronze part. I thought trying to solder a copper part on there was just pushing my luck too far.

And finally fitted to the engine.

I just need to finish off the rubber hoses to complete the build. They will be similar to those on the black engine.

In addition to the exhausts I’ve also got around to finishing off the clutch. I call it that because I can’t think what else it would be, but I’m not actually certain of it. The thing has a massive mechanical advantage built in to it though, and it’s the only mechanism I can think of that would require that.

If you recall from my previous post I’d designed it in CAD and was intending to build it from photoetched parts.

The first version looked a bit weedy compared to the pics of the real thing, but did at least serve to prove the concept.

Clutch made from 0.9mm brass sheet.

The parts were eventually made from etched  1.5mm brass sheet.

The parts in various states of completion.

After burnishing they were installed on both engines. The thicker section looks much more in scale.

Final version of the clutch release mechanism. The lever turns the rising cam which in turn lifts the central pillar. The bolt on the left hand end provides and adjustable pivot point.

Another area that was finally completed was the carburettor controls on the burgundy engine. The black engine’s controls are much simpler as they don’t have to connect to anything and can be left as they were on an ‘as delivered’ engine.

However, as the burgundy one is going in the boat it does needs connections that can properly link to the cockpit controls. To that end I built a small brass confection out of sheet and tube to simulate some sort of Bowden cable arrangement.

I just need to run some thing black wires into the tubes once it’s installed in the boat.

I’ve finally got around to adding a maker’s nameplate to the burgundy engine too.

As the black engine will be a stand alone model in a little glass case I’ve made some name plates to go with it. They are the usual etched brass affairs, and are replicas of the plates actually fitted on the model. In fact the etch masks were made using the same print files scaled up.

Etched, filed and drilled.

Stained and lacquered.

Having installed the exhausts on the burgundy engine it was possible to start test fitting the thing in the  Miss Severn model. I’d already checked the fit with my rough and ready 3D printed space model, but it was still a bit of a relief to find it went in without any problems.

I can now start to plan the layout of the engine bay. One of the main features of this will be the exhaust run to connect up with the kit’s in the cockpit. That requires some form of flexible coupling and I’m intending to use some braided oil pipe that I have to hand. A rough mock up of the what is planned is shown below and is based on some of the high temp piping that I have seen installed in aircraft.

Further updates on the engine bay fitting and equipping will appear a under  the ‘Miss Severn’ series on this blog.

There will be one more engine one though,  to complete the black engine’s build log.