no comemnt !

it doesn't broke during a flight

this morning I was checking the valve clearance and I untighten the 3/8 lock nut and .......

I will buy the new ones ith a screw driver and not a CHC

Would like to see close up pictures of both broken surfaces

jc

BSc(Metallurgy)

with enough tension anything will break!

Must be a tough spanner

I apply 32 N.m (24 ft.lbs) to the lock nut (I think it's the good toke)

I will try to make a good picture

MicheL

Broken adjuster

IF the tension was as specified them the materiel is suspect. Heat treatment perhaps? ( or maybe overtightened previously ) Have the hardness tested....Nev

broken adjuster

I've seen that failure before,when the nut was over-torqued and it failed in the air. The engine then failed too as the rest of the adjuster screwed itself out.

Those socket-adjusters needed less torque than a bolt that size because there is a lot less metal.

I can understand how you don't want the nut to come loose, so you apply plenty of torque to it when you do an adjustment.

So most of us changed to the slot-adjusters years ago.

It was good luck for this to happen on the ground.

...Bruce

I think the problem comes from the hole for the CHC that goes int the screx

If you look at the new one there's no CHC but a srew driver crack

Slot verses Hex (internal)

Think you are both spot on there.. Nev

These are really old adjusters, Jabiru changed to the slotted screw type many years ago because of this problem.

These are really old adjusters, Jabiru changed to the slotted screw type many years ago because of this problem.

Jabiru didn't edit a BS for this problem ?

MicheL

Replace?

Yes David I would replace the lot as they would not be a high cost item. IF i wasn't sure of the history of the aircraft, ( some one may have overtightened them in a previous life) I would replace them anyhow. A small item like this can bring you unstuck very easily. Nev

I send an order to get the parts

I hope i'll got them next week

jabiru parts

Bon Marche Michel. Nev

:big_grin:

These are really early heads. Do yourself a favour change them. I got some of the ones before the thin finned models with 20-40 hours on them from Jabiru for a very reasonable price. They work well on my solid lift motor No 506, huge power increase, the orginals gave all sorts of problems including cracking.

Why do you want me to replace parts that still work ?

Cylinder heads are expensive here (price + port + taxes + vat)

it's about 1/2 the price of a brand new engine !!!!!!!!

I've mounted the new tappet screws on Tuesday (the 19) and after cleaning the bing carb (ultrasound wave) I make a test flight

all is ok now (it was supposed to be a ground test but the plane goes in the air)

[media=vimeo]16028913[/media]

MicheL