RogerLewis

But I find it hard to interpret which part of the engine is causing the stiffness when hot and also what is normal due to my lack of exprience on the type.Without doing an actual compression [gauge] test hot vs cold how would you know. Cheers

The Jabiru engine will typically get stiff when the barrels distort when hot. You can check this by carrying out the following procedure:

1. hand swing your prop to checking all the compressions and more importantly checking for stiffness when the engine is cold.

2. Run the engine for 2 mins at 1200 rpm and then shut down

3. Hand swing the engine again and check for stiffness.

if the engine feels stiffer then it is because the barrels are beginning to distort. I say this because after 2 min at 1200 rpm only the barrels get hot.

Rule of thumb. If you fly the aircraft and shut down always watch the prop. If it kicks back then the engine is acceptable.

If the engine gets really stiff then it will need remedial work. Essentially this means removing and honing the barrels and using re-worked barrel base nuts. When re-torquing, check for barrel going stiff using a hot air gun.

Roger Lewis

My husband had his J160's SB8 done, requiring the new hydraulic lifters with hollow push rods etc.After doing the first cylinder head bolt torque he also checked the lifters for clearance. With the engine turned so that the cam lobes facing away from the nr 1 cylinder (valves fully closed) he compressed the lifter by pushing with his thumb hard on the bottom of the tappet. After about 10 sec. the tappet had about 1mm play between the valve and tappet. He then checked all the valves the same way by rotating the engine and compressing the lifters.

All the inlet valves had zero play - so no compressing the lifters and were solid against the valves. He also found one exhaust valve without any play. Can this be correct? It seems as if the push rods are to long....

 

(I hope I explained correct!)