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Author Topic: Alternative inlet rocker oil line  (Read 103 times)


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Alternative inlet rocker oil line
« on: August 31, 2017, 12:41:01 am »
First post since the Photobucket ransom, so hope you can see the pix?

Having recently suffered a severely worn inlet rocker after only 21,000 km on what was (probably) a 'new' crated engine, it looks like an additional oil feed is a necessity; not a luxury. The standard fix is to piggy-back a second oil feed onto the banjo bolt on the right side of the rocker box, and lead a huge braided oil line (same size as the primary feed line) to a machined hole in the inlet inspection cover. The additional line is restricted with a Dellorto carburettor jet, to limit the oil flow, and limit the effect on the oil pressure to the journals on the rocker spindles.
I was looking for a more elegant solution, and the initial idea was to either split the tube that joins the two banjos, and fit a tee to a smaller oil line carrying the feed to the inlet, or tap into the top banjo to fit a second feed. The objective was to eliminate the piggy-back and to minimise the size of the feed pipe, given that it needs only an occasional drip.
In one of those 'sleep on it, and you'll have the answer in the morning' moments, it occurred to me that the oil could be fed from right to left through the rocker spindle, which is already drilled half way through to deliver oil to the two journals. A quick pass with a file confirmed that the spindles are soft, so I called on Tonya's machining skills to turn the idea into reality. We drilled a 3mm hole from the left side, to meet the primary feed from the right. The new hole was bored and tapped 1/8" BSPP to accept a banjo fitting and a flow restrictor. Rather than use a carburettor jet, Tonya suggested a brass grubscrew, which was drilled 0.6mm to restrict the flow. A sealing washer is fitted below to ensure the oil can flow only through the 0.6mm hole.

IMG_5715 by bancquo

Here's the left side of the spindle after machining, showing the through hole, the tapped hole, and the counterbore to provide a flat surface for the union. There's enough left of the original slot to lock the spindle when tightening the acorn nut at the oil feed end.

IMG_5704 by bancquo

IMG_5701 by bancquo

Showing the hole goes right through:

IMG_5700 by bancquo

The union is a 1/8" BSPP banjo to 4mm compression fitting (it's not tightenend up yet - that will wait until the rebuild)

IMG_5698 by bancquo

Fitting at the top is identical, with the cover drilled and tapped 1/8" BSPP

IMG_5694 by bancquo

Here's the full assembly:

IMG_5693 by bancquo

IMG_5691 by bancquo

I think it's a lot less obtrusive than the standard fix, but it's going to be a while before I get it tested, as there's a long wait for all the other work that needs done...

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Re: Alternative inlet rocker oil line
« Reply #1 on: September 02, 2017, 09:31:32 pm »
bonjour joli travail j'aime les améliorations sur le falcone
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