Just sharing some pics of a recent resto. This one is an AMECO (Australian Marine Engine Company) Seasprite, manufactured in Melbourne between 1947 and 1950.
The restoration was fairly straight forward. The crank presented the biggest challenge along the way as the original was broken. I found another which was also broken, but provided the parts needed to make one crank from the two.
Beautiful job. What an interesting outboard. I love seeing all of the Europe and Australia specific outboards. They are certainly not something we ever get to see in North America.
How did you go about putting the crank back together?
Was a pain in the backside to be honest with you. Some prior aligning using standard tools eg vernier etc, followed by numerous assemble (in crank) rotate, disassemble, tweak, reassemble, rotate etc etc etc. Finally got it to rotate nicely, but I wouldn't want to do it again.
As Oyster so correctly stated “the big end pin is held in the crank web by an interference fit”.
In a Seagull 3 piece crankshaft as fitted to post 89 Qubs (Curlew, Osprey, Kingfisher & 5R’s) which look like they have a shorter stroke than your Seasprite, the interference fit is generated by a hard big end pin that is 0.1mm bigger than the hole it gets pressed into.
On a forged EN40B Seagull crankshaft this requires a considerable amount of pressure, and as the pin is so hard, causes the hole to get bigger & slightly misshapen as it stretches easier in the areas with a thinner wall thickness, leaving a hole shaped a bit like a Wankel rotor.
To rebuild a 3 piece Seagull crankshaft it is then necessary to have the holes ground round again & a new oversize pin made that gives the correct interference fit.
Removing & replacing the same pin several times can stretch the hole & reduce the crank webs grip every time you do it, this is more of a problem with bronze main bearings rather than ball races & might be good enough for a 2 minute showing off run in your water butt, but might be very different for a sunny afternoon on the Yarra or the Gippsland lakes.
Make it idiot proof and someone will make a better idiot.
When I was an apprentice a mate of mine used to race a 50cc road racer that revved to 16,000 RPM. He used to have to replace the big end every 2 race meetings. He used to bring it in to us in the tool room and we would freeze the pin and warm the crank and press in the new pin. Oversized pins were available and the crank could be reamed out, but the crank only lasted one race season. Then it would have to be checked for alignment and runout between centres.
I used to have all my cranks rebuilt at Alpha Bearings in Birmingham, who are sadly no longer with us since Max passed on.
All the cranks I rebuilt were always fitted with new pins, bearings & steel conrods & as I used to buy the rods & bearings in batches of 25 to get the price down, I probably have 5 new rods & both bearings left in the drawer, so if anybody wants some.
If anyone knows someone in the UK with the ability to build & rebuild cranks, please let me know.
I also have quite a few, new no longer available Seagull cranks, 170/125 & bronze Kingfisher/QuBs with the correct conrods & new century & 40 series cranks that I'm never going to use.
Finding a toolroom in the UK, would be a hard task let alone trying to do a homer in it, in 2018!
Make it idiot proof and someone will make a better idiot.
That's very strange, I had a call from their secretary asking if I wanted my box of samples & tooling back or should they dump it, as they were closing on Friday at the end of that week, & all the staff except her had been let go.
On my previous visit I'd left Max with a center fixture that Max was going to check to ensure it was in perfect alignment, it wasn't in my box so I went to see the owner, who'd bought the company from Max 2 or 3 years ago to see if he'd seen it around, no trace, but was told a lot had been binned by then, I will try contacting them on Monday.
Make it idiot proof and someone will make a better idiot.
