Push rods came out of there seat.

[Kai]

Hi Kia.
Thanks for the reply. Forgive my ignorance on this. Your comment on this engine been a 2nd generation caught my attention and a bit of a relief.Is there a reference which states what serial numbers fall into 1st, 2nd generations.
My serial number on this is 22A 1130. Which, I hope it is not a1st generation. I’ve been told that you can no longer get heads for 1st gen engines. So if it’s a second gene then that takes a load off. At least until I get the bill on what I need to do.

Thanks again.
Mark

First the good news: the various Jab generations with their pletoria of small and large changes introduced in the production, can be found in the last pages of the engine overhaul manuals, available on jabiru.net.au.

Not so good is that broadly speaking Jab operates with 4 different generations- not only two as you suggest.

Parts for them are generally only to a small degree interchangeable. Your low serial# falls in the category of an early gen2 UNIT.

The by now very old gen1 engines had various types of round heads with thick fins; there can’t be many of them still in operation anywhere.

I have had two of the gen2 engines like yours myself. The earliest one #1339 with the black starter housing, and one slightly newer with the bigger, polished steel starter #1430. Both the gen1 and -2 engines had mech lifters.

All gen3 engines had hydraulic lifters and narrow finned, better cooling heads. I could not list one source worldwide for any new aircooled heads that would fit either the gen1, -2, or -3 units.

Jab is presently marketing the gen4 series. It’s a completely new engine, where in addition to other changes especially heads, cylinders, and pistons radically differ from previous generations.

Sorry.

[Kai]

Well,

Yes- either way you look at it, these units are a challenge to cool properly- especially the critical underside of the heads.

Kai

[Kai]

You are correct with your assumptions about the valve seats. But technically speaking, here we go, plasticity is not a metallurgical term. Yield strength comes close to it. That's the strength at which it yields and does not spring back. Aluminum expands four times as much as steel valve seat when it's heated. micro inches/degree C. per inch. That's probably why they put a max on head temp. When an alum head expands the holes get larger not smaller. Valve seats have to be shrink fit when they are installed, by several methods, and pressed into the seat in order to be able to absorb the heat expansion without coming loose. The head goes through an expansion/contraction cycle with every engine run which might also tend to loosen head bolts. It would be a good idea to torque check them once in a while. I need change for my two cents worth.

I can offer no argument! Remind me to reimbourse you should we ever meet :-)

Kai

[Wood]

After 3 1/2 months and numerous headaches from dealing with jabiru and trying to get the right parts I finally get my heads back. I must say Jabiru support is next to none once they have your money. Very disappointing. The problems I had from people not doing there jobs properly and not caring was disgraceful and certainly a let down. From sending items with no info to what that part needs to wrong part numbers on items. And worst of all. After been nice about the issue not an apology for their screw ups.

I only hope this engine after all this this engine lasts until I can replace it.


Mark

[Wood]

Hi all. Hope your all doing well. I was a happy man the other day as I finally got my heads back on and getting things ready he tet flight when it warms up. Bit more and the runway conditions permit.

Looking forward to getting back into the at.
Mark