ZTU oiling

Dennis P · Apr 22, 2018

On the left rear corner of the block on the surface that the rear cylinder sits, there is a hole that goes into the crankcase. This is where the copper oiling line for the valves should terminate, but doesn't due to the hole drilled into the crank case. The front line does not have this & terninates at the gasket at the front left corner. Why is the rear not the same? It looks to me like a huge pressure drop on the upper oiling system. I think that I should plug this which would increase pressure all the way back to the rod bearings. I will try to post picture to better explain. Thanks!

T.R.K. · Apr 22, 2018

Somebody will correct me if I am wrong.

I am thinking the restirction in the rocker oiling circuit is in the center holes and that hole at the rear is just so the excess oil that doesn't drip on the rockers has somewhere to go to get back to the sump. (You don't need much oil, just a drop on each rocker every few seconds.)

I think the restrictors are short small diameter copper tubes that are flared on one end and forced in the block at the center holes where the oil comes up from. The restrictors allow oil pressure to build up everywhere else in the oil circuit. (If they are not present, probably the tube that comes up from the center main is very tiny. I forget which engines had what parts on them.)

I am thinking the front cylinder block should have provision for an oil tube over to the top oil pump shaft bushing at the front of the block. The tube feeds oil to the bushing just below the distribuitor or magneto, whichever your ZTU uses.

So essentially, you just leave the upper oil equipment alone and don't try to re-engineer what worked for the last 60 plus years.

ZTU oiling

Dennis P

Member

T.R.K.

Well-known Member

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