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Re: SpAriel MkII aka The Hermanator

Posted: Fri Oct 16, 2020 8:28 pm
by paul.jameson
To understand the X suffix to engine number DJ2050X you need to refer to the Service Bulletins, in this case number 85 of September 1949. The relevant section reads:

" ALL SINGLE CYLINDER MODELS.

PISTON AND OIL PUMPS. MODIFICATION.

All 1949 models incorporating the letter 'X' after the engine serial numbers, are fitted with a modified piston incorporating a scraper ring in the lower groove and a modified oil pump with a larger diameter (1/4") delivery plunger.
This arrangement has been introduced to eliminate piston slap which has been more prevalent since the use of post war materials was necessary. Reference should be made to the 1949 Single Cylinder Supplementary Spares list - Page 8 - for new part numbers relative."

Re: SpAriel MkII aka The Hermanator

Posted: Sat Oct 17, 2020 12:15 am
by Simon.Gardiner
That is one helluva weird con-rod!
All I can think of is that the factory received a batch of 'funny' forgings and instead of throwing them out (maybe supply was a tad 'iffy' back in the late 1940s) someone found a creative solution.... :D
I've got a pair of steel VH flywheels and they're definitely (about 7oz per wheel, so getting on towards 1lb per pair) heavier than my later caste iron wheels (and I've been puzzled about that superfluous 2nd 'sludge trap' in the drive-side as well!).

SG

Re: SpAriel MkII aka The Hermanator

Posted: Sat Oct 17, 2020 8:58 pm
by Vincent.vanGinneke
Thanks Paul, you know your way in the documents !


And as a teaser .... see pic.
350 bigend with 500 outer.JPG

Placed a 500 bigend outer ring over the eye, it looks like it could be used for machining a 500 bigend in it.
Put that in a 350 crank plus a larger piston......

no, no, I am not going to do that !

Re: SpAriel MkII aka The Hermanator

Posted: Sun Oct 18, 2020 2:10 am
by Simon.Gardiner
All 'big-rib' 350 rods will easily take machining-out to take a 500 big-end (and it's fairly straightforward to machine the flywheels for the parallel-fit pin) - old 'tuning tip' passed on to me last century - but that rod you've got looks like it's been made with just that in mind!

SG