Hi all,

I am planning on using a 1 1/2" nippy crank and rods in the engine i am building for my ulster rep.

I have been told it is recomended to enlarge the oil scoops in the crank to aid the spit and hope as they are too shallow. Does anybody have any experience of this modification? I would like soe idea of what has worked for others before i start milling chunks out of the crank.

As discussed in other threads i will be fitting an enlarged / alternative pump and bigger oil jets.

Obviously i will need to ballance the crank afterwards.

Before someone suggests it, no im not going to fit a phoenix. Just putting a new part in does not prevent the fatigue of the crank it just puts it off for a bit (i cant afford one anyway im a skint engineering student!). I will be fitting a floppy flywheel.

Regards

Rob

Rob,

I have opened up the oil scopps on the Pheonix cranks I have, I used a countersink cutter to open them out carefully (whilst in the crankcase, stopping to push wire or diesel through the oil jets to check for best alignment. I ddin't remove much and the track to the oilway seemd clearer.

Good luck

Ruairidh

Ruairidh,

I cant remember what the phoenix scoops look like as standard, that did occur to me as an option though.

The scoops on a nippy crank look like they were machined with a dovetail cutter so have a nice re-entrant feature to catch the oil. The problem is its not very deep and the oil hole goes from the flat face in the bottom of the slot. I was thinking of using a ball nose cutter on the milling machine to cut a re-entrant radius bottom slot. The problem is the oil hole goes in a straight line from the scoop so its a bit tricky to know how to attack it.

Regards

Rob

*The problem is the oil hole goes in a straight line from the scoop to the big end so its a bit tricky to know how to attack it.

That might make more sense

Rob
You mention bigger pump and jets? Have you considered
the twin jet set up? i.e a duplicate set of jets on the other side to increase the period of lubrication? I beleive this was a 750 racing mod that seems to be a good idea?

Steve

Rob,
This is an opinion not experience!

I would follow the Mike Forrest logic ('fill your boots with oil' - reprinted in the companion). Try and get the scoops to hold more volume and perhaps make them a little wider to catch more oil mist or misdirected jets. Try drilling the oil hole at the bottom of the scoop out to the next size, it gives a little bit more volume and will clear any dirt/carbon/grime etc. Radius the edges well at both ends. Are you taking out the brass plugs? There's just enough on the hole size (on a standard 1 5/16" anyway) to get a 1/8"BSP thread and screwed plugs - the same size as the grease plugs in the hubs. Loctite in modern Allen drive type plugs.

I would recommend the double jet set up as well - more oil and less chance of totally blocking the oil supply to two bearings. It does need an enlarged oil pump - that bit is experience! Mike recommended bending the jets with a rod up the hole - subsequent best practice was a bar with a hole drilled in the end to just fit over the jet.

Whilst the idea is good I'm not sure if the oil does come out of the jet as a 'jet' or does the pressure give a spray effect?

Dave