Jack Donsen

Google Jabiru Sth Africa and ask for Len Alford. Google offset wrist pin and see that the pin should go towards the major thrust side. Then measure an old piston and see that the wrist pin is to the anti thrust side because the direction of rotation has been reversed for RH prop compared to SAE spec auto engine. I have corrected wrist pin offset in several Jabiru experimentals and they work heaps better. CHT drops 30F, Oil drops 10F and you gain 50 RPM - guaranteed. Just rotate the pistons so the arrow faces rearwards.

Hi Mick, Your assessment is correct. The reversal of the crank rotation effectively moved the wrist pin offset to the wrong side of the centreline. Jabiru Sth Africa have been reversing pistons from new for over 10 years and are getting great results in achieving 1000 hours TBO. If you record your T's and P's prior to correcting the offset and comparing them after, you will drop CHT by 30 degrees F and the oil temp will drop about 10F and you will pick up an extra 50 RPM at full static.