Tuesday 30 June 2009

Engineering


Spent the last few weeks delivering the Invicta Viper to her new owners and attacking the trailer with assorted wire brushes and pots of
Hammerite...

The side bunks and winch post will go on after the boat is on top.

Next up was converting the engine from 'short' (aka standard) to 'long' shaft and tidying it up ready for the Broom.


The engine is a 1971 25HP Johnson Sea-Horse and I'm pretty pleased about this as it should have enough 'grunt' to provide some fun, while not being overpowered for our local rivers.
The engine is also around the same age as the boat and even has the added bonus of electric start.
I'm no mechanic, but I'm learning these old OMC (Outboard Motor Corporation - Johnson/Evinrude) engines are pretty easy to work on with basic tools and knowledge - also a bonus.

Shaft Conversion
Converting the shaft length is (on paper) relatively straightforward:

  1. Disconnect gear shift linkage
  2. Undo bolts
  3. Pull away bottom of leg with gearcase
  4. Replace the water cooling pipe, gearshift connector, drive shaft and sleeve with longer versions
  5. Insert a 5" long leg extension piece
  6. Bolt it all back together

The first problem was gathering all the bits together, I was lucky enough to have a long drive shaft (an expensive item) supplied as a spare with the engine - the other bits were all courtesy of the CMBA parts store (aaah - the advantages of joining the right club). So armed with all the necessary bits, I called upon the services of a friend to give me a hand. Well that's not true really - he actually did the whole job for me - thanks Geoff! The whole process went relatively smoothly though we couldn't find a long water cooling tube (basically a copper pipe) and an extension to the existing one had to be fabricated. We also took the opportunity to replace the impellor and renew the gearcase oil. Oddly, the most difficult thing to track down was the long bolt to fit the new leg extension piece, in the end I gave up and used a stainless steel stud, cut to length.

Cosmetic Makeover...
Although in overall good shape, the engine was going to look comparitively tatty when hung on the back of Gina, so I decided to give her a quick once over on the cosmetic front. The hood (GRP) was first sanded, then filled, primed, painted and polished. The raised 'Johnson' logo was then picked out using a black wedge tipped permanent marker and lacquered. Finally, new decals were obtained from Nana's Decal Store in Canada - great price and service! Just need a new piece of trim for the bottom and it'll be job done.



The rest of the engine was sanded down - a tedious and thankless task - until it looked something like this:

You can see the 5" leg extension here (the yellowy-green piece)

Everything was masked off that could be - engine itself, prop, grease nipples etc. It was then primed with an etch primer (it was down to bare metal in many places) followed by plenty of coats of 'Ford Tourmaline Green Metallic' - courtesy of Halfords 'rattle-cans'. This was finished off with around 4 x coats of petrol resistant clear lacquer, again - job done!



Maybe not a Concours d'Elegance prizewinner, but at least it's clean and tidy now.

Next job is to get 'Gina' up on the trailer... so watch this space!