Macchi M-5

[Mike Norris (UK)]

Hi all,
The valve operation on the 'Isotta Fraschini' V4B engine is strange by comparison to other in-line engines of the period.
Normally the inlet and exhaust valves on each cylinder would be operated from a single overhead 'camshaft'.
However photographs and drawing for this engine show three separate shafts, each operating the valves for its cylinder bank.
I can only assume the drive for the three shafts is located below them in the lower half of the overall housing, which is not represented on the kit part.
The kit part, including the inlet manifolds seems to have been modelled more on that fitted, for example, on the Daimler-Mercedes in-line engines.



I've modified the overhead operating shaft by cutting it into the three sections, removing the kit shaft and replacing it with 1.8 mm diameter tubing.
This required some re-profiling of the operating shaft mountings at each end of the engine (radiator and propeller shaft ends), including 2 mm extension to fit to the end vertical drives.
The tubes still need to be blocked at each end as the shafts were solid, not tubular.


 
This has also shown up several other areas of the engine that require attention (so far):
Both inlet manifolds and the two carburettors are incorrectly moulded - the manifolds too long and wrong shape - the carburettors are joined, but in fact were separately located.
No spark plugs location.
No water pump supplied in the kit.

Mike
 

[Alexis]

You got your work cut for you correcting the engine , it over all doesn't have great detail with in the kit parts . The mounting bolts for the cylinders seem off , or is it just me ?

You are a brave man to tackle this kit Mike .


Terri

[RLWP]

Hi all,
The valve operation on the 'Isotta Fraschini' V4B engine is strange by comparison to other in-line engines of the period.
Normally the inlet and exhaust valves on each cylinder would be operated from a single overhead 'camshaft'.
However photographs and drawing for this engine show three separate shafts, each operating the valves for its cylinder bank.
I can only assume the drive for the three shafts is located below them in the lower half of the overall housing, which is not represented on the kit part.

Mike

My interpretation is that the camshaft runs below the rockers, the cam followers are a sort of two armed bell crank with a tubular body. One arm is inside the cambox, the tube passes out the side of the box and operates the valve via the other arm on the outside

It is in my mind that I found a drawing somewhere illustrating that - I wonder where?

Based on that, there shouldn't be a gap between the cylinder heads, so the kit is wrong in that area too!

Richard

[RLWP]

There are more images here:

https://www.bonhams.com/auctions/23555/lot/71/?category=list

Richard

[RLWP]

Richard

[Mike Norris (UK)]

Hi all,

Terri:
Yes the engine lacks a lot of detail and has errors - even our late and great 'Des' missed some on his build.

So far I've noted:
Valve gear operating gear incorrect.
Inlet manifolds and carburettors incorrect.
No spark plug locations.
No water pump or coolant pipes.
Cylinders separated at the base, not joined.
No magnetos.
No ignition lead support tubes.
No oil pump.
All engine control rods etc need scratch building (as expected).
No oil fillers (x2) for the crankcase.
No engine data plate decals.

Rich:
Those photograph are new to me but at least they do confirm my thoughts on how the valve gear was operated.
Your explanation follows what I suspected.
You're correct, the cylinder bases for each bank are joined, although the tops are riveted cooling jackets and are very close, but not actually joined.
I did note that but couldn't fill them in until they were fitted to the crankcase.
Thanks for your confirmation on this,

Mike

[RLWP]

I hadn't come across those before, they are very useful!

I have downloaded them for future reference

Richard

[Mike Norris (UK)]

Hi all,
The radiator assembly done.
This needs to be done now and added into the radiator housing and engine bottom fairing.
Then I can start to work on the missing components at the forward end of the engine, such as magnetos, pipes etc,

Mike

[AndRoby67]

Hi Mike,
nothing more than "compliments at full throttle"!
Your work is like "scientist modelling".
The Isotta Fraschini was an original design.
Roberto

[Mike Norris (UK)]

Thanks Roberto.

Hi all,
Work continues on modifying the kit engine to represent what the engine actually looked like.
I've now added a 'camshaft' below the 3 vale lever shafts from 1.8 mm diameter tube.
Also added a pair of 'Taurus' magnetos and a drive shaft (from the spares box).
Finally the drive at the rear end of the engine (1.0 mm tube and drive head modified from spares).

It's all a bit rough at the moment and I still need to add water pump and if possible and oil pump, plus their associated pipes (where possible).
Also the ignition lead support tube etc.

Mike

[Alexis]

Excellent job on the rad Mike , engine is coming along nicely with the details 


Terri

[RAGIII]

Radiator and engine are looking excellent! Your attention to detail is amazing!
RAGIII

[Mike Norris (UK)]

Hi all,
The engine was fitted with a water pump for the cooling system.
On the actual engine the pump was located forward (radiator end) of the engine, below the magnetos and engine sump/crank case joint.
I wanted to represent the water pump and its pipe work, but due to space restrictions, I had to locate it higher on the engine than was actually the case.
 
The kit engine has a pronounced 'step' in the engine sump at the end facing the radiator (forward end). This 'step' is intended to fit under the installed radiator.
I've cut away this 'step' and fitted two propeller shaft housings from my spares box to recreate the previously rounded end of the sump.
To one side I've added a modified water pump, again from my spares box.

Still more to do - plugs and wiring, ignition lead support tubes, oil filler pipes and what pipe work and controls I can fit.
The whole assembly still needs cleaning up and painting of course.

Mike

[RAGIII]

Clever use of spare parts. I like what you are doing a lot!
RAGIII

[PrzemoL]

Oh my, I wonder how I missed this build log. Great modelling, Mike, as usual. And you thread will be a great source of hints when I finally get to my HPH M.5 which has been waiting far too long. Thanks for showing us your research and modelling.