oil pressure

[jimdee]

I had my TO20 Z120 engine overhauled a couple of years ago. The block cracked last summer and I was able to locate another block on ebay. I switched the entire engine components from the cracked block to the replacement block. However oil is not being pumped to the rocket arm. I can disconnect the oil pressure gauge from the block and oil bubbles out when cranking the engine. What would prevent oil from reaching the rocker arm?

 

[Jerry/MT]

The rocker arm receives oil from the rear cam bearing through a drilled hole. That hole maybe clogged. What the oil pressure gauge say? If you don"t have oil pressure, perhaps the pick up tube is cracked or leaking and thus the oil pump won"t prime.

 

[gshadel]

the oil flow at the rocker arm is not much, more of a spitting/splattering than a steady flow. You can run the engine without the valve cover to set check valve tappet clearances, etc. (per the manual), without getting an oil bath.
But, if you are in doubt about your oil flow to the valves, do as Jerry suggests and check that cam port. If you have ~20+ psi oil pressure, you should be getting sufficient oil to the rocker arm. If you have < 20 psi, especially at working speed, your oil pump and/or relief is suspect and should be rebuilt.

George

 

[John (UK)]

If it is bubbling like you say that would seem to indicate it is drawing air and the pick-up pipe could be cracked like Jerry says, While you have the oil pan off, check the oil Pump for wear.Should be less than .010" between the end of the rotor lobes and the housing of the Pump..John... [email protected]