Brief Description: Completed fitting values and rockers and CHT mod
Once the values where in I fitted the new rockers. These are Camit rockers and they look to be significantly improved over the original Jabiru hydrolic lifter. The overall geometry is a little better with th epuch rod being more verticle and the oil flow to the bearing is much improved.
I then used my milling machine to mill the centeral mounting hole area for the CHT probe as per Jabiru modification
The cylinder heads where modified in accordance with AVDALSR085-1_CHT_sensor_mod.
I created a 10-32 thread in the hole so that I could drill through a 10-32 cap screw and run the thermocouple at the bottom of the existing hole. The #30 drill used to drill the hole dia for 12mm then tap a 1-32 thread down 10mm. The hole is 20mm deep originally. The enlarged hole and thread run down to just above the level of the spark plug seat. Not into the head proper but only within the fin
The thermocouple will be incased in heat shrink and an aluminum tube placed at the bottom of the hole. THe wire (including braid) running up through the 10-32 cap screw drillled out with a 7/64 drill. Place some thermo paste in the bottom of the hole with the thermocouple tip. The thermocouple will be about 15mm from the combustion chamber wall between the two spark plugs.
This should give an excellent indication of the actual head aluminum temperature. The reading should be higher than placing the thermo couple on a tab or under the spark plug. Some testing may be required to find the adjustment factor for comparison with other aircraft users.
The metallurgy of aluminum suggest that the strength decreases rapidly with temperature rise at around 400F.
