Converting Madeira 40 to Madeira 50 (Part 1)

When I did the carburetor cleaning some weeks ago I noticed that my outboard was Madeira 40 although it had Madeira 40 XS decals.

I have been playing with the idea how to convert this outboard to 50 HP and been studying the part listings.

This is what you need to change (I suppose):

• Both carburetors need to be replaced (going from Dellorto 34/30 to 38/34).
• The intake manifolds, those are the parts where reed valves are attached to.
• The engine head is different.
• Luckily there is no exhaust separator plate in Madeira 40 so no need to remove that!

I finally convinced myself that let's do the carburetors and intake manifolds and see what happens. The engine head of 50 HP model most probably gives more compression, I don't know how expensive that is but one can get similar results by shaving the engine head, I may want to try that later.

I was not able to find second hand carburetors so I decided to order new ones from Engine Marine Part. This conversion is not financially very well justified as the new carbs and intake manifolds costed around 800 € plus shipping 😂.

This is the upgrade plan:

1. Remove the air box
2. Remove Dellorto 34/30 carburetors.
3. Remove Madeira 40 intake manifolds.
4. Remove reed valves from Madeira 40 intake manifolds.
5. Remove tubes and plastic connectors from intake manifolds.
6. Attach reed valves to Madeira 50 intake manifolds.
7. Attach plastic connectors and tubes to Madeira 50 intake manifolds.
8. Attach Madeira 50 intake manifolds, connect oil tubes, and two air? tubes.
9. Move fuel connectors and linking arms from old carburetors to new ones.
10. Attach Dellorto 38/34 carburetors.
11. Connect fuel hose.
12. Make sure that carburetors are synced and closed at idle. Adjust idle and mixture.
13. Put the airbox back.
14. Start the engine!

Stock Selva Madeira 40 intake manifolds.

Madeira 40 intake manifolds removed.

Reed valves still attached to Madeira 40 intake manfifolds.

Reed valves and connectors moved from Madeira 40 intake
 manifolds (lower items) to to Madeira 50 intake manifolds (upper items).

Link arms, fuel connectors and all other stuff
moved to Dellorto OVC 38/34 carburetors.

The new intake manifolds attached.

The new carburetors attached, testing WOT throttle position.

The carburetor change operation completed.

First startup after the carburetor change, maybe it's a little bit more angry! 😎

Check also Part 2

Testing Hill Marine Semi Cleaver

Today it was time to test Hill Marine semi cleaver propeller on Selva Madeira 40. I switched from Solas Amita 3 11"x17" aluminium propeller. Many people say that you lose RPMs when switching from aluminum to stainless steel, some say that you gain RPMs. In my case I was going from 17" pitch to 18" so the RPMs should drop in any case. Semi cleaver is of course very different kind of propeller compared to round ear Solas.

I did the installation when the boat was in water, no major problems, I used two washers although the hub kit contained only one.

Hill Marine semi cleaver 11 1/4 x 18 on Madeira 40.

The stock nut and pin worked well.

This semi cleaver is a lot heavier than Solas aluminium propeller but I didn't notice any problems when switching from neutral to forward. The weather was quite windy and it was not able to get optimal results. I noticed that the RPMs at WOT where around 5400 rpms whereas with Solas they were above 5600 rpms, also the top speed was more than 3 knots lower.
I was able to trim motor up without the propeller losing grip, it seems that semi cleaver (as well as cleavers) likes run close to the surface of water.

I was not happy with the performance, maybe the propeller has too much pitch, I'm considering raising the engine to the highest mounting holes. I need to test again in calmer conditions and will try to trim the motor as up as possible. It is said that cleavers create transom lift but I did not notice anything worth mentioning.

Raising the engine two holes

My Selva Madeira 40 was installed as low as possible (the highest mounting holes).
I have noticed a long rooster tail and excessive spraying so I decided to raise the engine two mounting holes, that is the second highest position available.

Before

After

After raising the engine the RPMs increased from 5300 rpm to 5600 rpm using Solas 11x17" aluminium propeller and the speed increase was about three knots.
I think the engine can be raised even more as the propeller grips quite well and can be trimmed up without problems.

Here is a video taken after the the engine was raised.

Carburetor cleaning

Removing the carburetors

In order to remove the carburetors you must first remove the airbox.

Selva Madeira 40/40XS/50 airbox.

After that the carburetors can be removed by opening four bolts (two in each carburetor), the bolt holding electrochoke body and disconnecting fuel hose. Opening the carburetor bolts can be a little tricky as there is not that much space. Be careful not to lose the metal part called "electrochoke mounting plaque" when opening the bolt in electrochoke body.

Bolts that needs to be opened in order to remove carburetors.

Dellorto carburetors removed.

Intake manifolds and a peek of reed valves. 

Cleaning the carburetors

I was positively surprised how easy it was to disassemble Dellorto OVC 34/30 carburetors, clean those and put back together. First you need to detach carburetors from each other by disconnecting the rods syncing them and fuel hose. After that you can open the fuel bowl by opening four bolts.
Then you can unscrew the main jet / diffuser and the idle jet.

I noticed that in one the carburetors the idle jet was not positioned in the middle, I think it's a manufacturing fault as changing the idle jet did not correct the problem. I carefully bended the idle jet a little so that it was in the middle of the diffuser. My engine has been idling quite roughly so hopefully this might help a little.

You should check the jet sizes, correct main jet size for Madeira 40 is 160, for Madeira 40XS/50 it's 180. The idle jet size is 65 for Madeira 40 and 70 for Madeira 40XS/50. (Madeira 40XS/50 has larger 38/34 OVC carburetors).

Carburetors detached and float bowls removed.

The main jet, diffuser and idle jet.

Idle jet is not in the middle.

Idle jet position fixed by bending it a little.

Selva Madeira 40 compression test

Today I tested the compression for both cylinders. I have not done this previously so I was curious about the results. I did the test when the engine was cold and throttle was set to high idle position. The compression was a little above 130 PSI for both cylinders.
I don't have the service manual so I don't know where it should be, at least this is not a low value which is good. My outboard model is after all Selva 40, the 40 XS and 50 models have different engine heads so they might have even higher compression.