Justin's Raven

[grostek]

Finally... Spent the last two weeks building 3 different iterations of the throttle linkages. Each useless in its own little way. Finally got something workable - and it even fits when the fuel tank is in - there really is not much space up front!

Anyway, with the last of the metal work out of the way, I spent about two days cleaning the workshop - getting rid of every trace of metal shavings/dust from all the metal work - and this evening I finally started putting the engine together.

First step is the dry assembly - to plastiguage all the journal clearances. Crank and cam clearances are spot on - near the top of the VW 'new engine' spec. Cam end float is too tight though, so I will need to sand down the flanges a little (these are 'double thrust' cam bearings - not the stock VW bearings. Only measured one big-end so far, and it was quite tight, but still within the 'new engine' spec. Took 3 times to get it right. It is insanely difficult not to move the rod while torquing/loosening those nuts.

Will finish the other rods tomorrow, and then see how far I get with the final assembly (won't be _that_ far though, as I bought the wrong case nuts).

Plastiguaging the journals:

DSC00002.JPG

DSC00004.JPG

Hi Rudi,

Dry assembly as in zero oil during assembly, does not sound like a good idea think. I use Oil to assemble an engine
Dry comrod bearings on crank journals is asking for trouble. In my humble opinion.

Kind regards

Gunter Rostek

[justin.schoeman]

Perhaps I am using the wrong terminology... I learned to build engines from an old mechanic, about 20 years ago (damn - has it been that long???).

Anyway - what I mean by 'dry assembly' is basically building the engine without oil, or grease - absolutely clean, but with plastiguage in every journal. Torque the whole thing up, and then strip it down again, and check the plastiguage for the clearance of each.

Then clean, and re-assemble with assembly lube (finding assembly lube these days turns out to be impossible - so I am just using white lithium, as recommended by AeroVee).

So far everything has measured up perfect, except for the thrust surface on the cam bearing. I will need to polish 0.04mm off the thrust faces. The big ends also measure up on the low end of the new spec. I would prefer a bit looser on an engine intended to run at high power settings, but it will have to do, as I had the crank nitrided, and I don't want to ruin the surface.

Since the engine showed signs of metal in the oil when I stripped it, I decided to do a thorough cleaning too. So I took all the galley plugs out of the crank and case. Even after a 'thorough' chemical clean by the engineering shop, you will be amazed by how much junk came out of the galleys with a decent scrubbing.

(PS - It is a type 1 engine - the type 4 is sitting under the bench, waiting for a huge cash injection - big bore kits, and stroker cranks for type 4s are obscenely expensive!)

(PPS - I will also be pre-oiling the engine with a Bob Hoover pre-oiler - basically take a garden pressure sprayer, and fill it with oil. Good for enough pressure to fill all the galleys, and test for leaks.)

(PPS - Thanks for the offer Oupa-G. I will give you a call when I get stuck - sounds like you learned the trade when it was still a 'craft' - not the hack job many modern motor builders perform...)

[justin.schoeman]

Somehow, nothing is ever as easy as you would hope.

The AeroVee has an interference fit for the prop hub on the crank. You freeze the crank, and heat the hub to 230C. Then, in theory, you just drop the hub on, and a few taps with a mallet will seat it.

My hub went straight on to within 0.016" of the end, and got stuck. AeroConversions (the manufacturer) said I could cold press it the rest of the way, but nothing will budge it. Waiting for further information from AeroConversions.

[grostek]

Somehow, nothing is ever as easy as you would hope.

The AeroVee has an interference fit for the prop hub on the crank. You freeze the crank, and heat the hub to 230C. Then, in theory, you just drop the hub on, and a few taps with a mallet will seat it.

My hub went straight on to within 0.016" of the end, and got stuck. AeroConversions (the manufacturer) said I could cold press it the rest of the way, but nothing will budge it. Waiting for further information from AeroConversions.

Eish,

That is very annoying and can drive a sane man to drink or worse.

Hope you get the prop hub off the crank without damage.

Kind regards,

Gunter Rostek

[justin.schoeman]

If I wasn't so depressed, I would be doing some serious swearing right now.

Found an engineer with a big enough press, and did the deed, BUT there was a bump on the face of the press which put an offset load on the hub, pressing it on skew. Pressed it off, and was going to try again, but when I measured up, the interference is below spec, so the hub is toast.

Anybody got a spare 912 going cheap?

[German]

[t-bird]

Hi Justin

When are you going to finish the aircraft ?

[justin.schoeman]

Hi Justin

When are you going to finish the aircraft ?

About a year ago... Or that was the plan .

The engine debacle really put a dent in my enthusiasm, but I am back on track now. I have been puttering with the electrics for the past few months. Being an electronic engineer, I thought it would be quick-quick... And I suppose in total man hours it is not too bad - just soooo tedious, it is difficult to get back into the workshop to finish it!

I actually took this photo last night of the completed panel:

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All tested and ready to go. Just need to take the completed wiring harnesses and install them in the fuselage. Also need to work on noise suppression on the radio power lines, as I am picking up flourescent light noise - so it will definitely pick up ignition noice.

Once the electrics are out of the way, it is time to sweep, clean, polish, vacuum (lather, rince, repeat) until the workshop is spotless, so that I can start engine assembly again.

I bought a new prop hub/#4 main bearing combo from Jean Crous (Aerokits). It is a thing of beauty. It looks to be indestructible, and does away with all of the issues of a press fit hub. Was also substantially cheaper than importing a new hub/crank combo from the states.

Can't wait to put it all together...

[justin.schoeman]

OK - A year and a half after buying a 'good condition, low hour' engine, I am finally on the verge of having a 'new condition, 0 hour engine'... Had to replace/re-machine just about every component, but it is finally comming together again.

This is the result of the first evening:

Everything measured and trial fitted. All clearances, end floats, etc. within new spec, everything flushed and cleaned. Tonight I close up the bottom end, and measure up the top-end geometry.

You can also see the new prop hub in this photo - the hub itself is a taper fit over the crank, and ends flush with the timing gear. It is fully supported over the length of that huge bearing you see at the end there...

[justin.schoeman]

OK - I am running out of words to describe the level of incompetence displayed by 'engineers'...

Although I knew that there was no interference (this was a previously running engine, right?), I decided to flip the engine horizontal so the rods could dangle, and I could rotate the crank. Lo and behold - it turns 90 degrees, and locks solid. Wiggle all the rods - they all move, so none of them are jammed. Fiddle prod, poke, take the cam shaft out - and it turns. Cam back in, and it doesn't turn - but the rods definitely aren't near it. Must be the gears, right?

Inspect the aluminium cam gear, and find a small gouge near the back edge. Hmmm.. . Have a look at the brass gear, and the very end of some teeth are bent - squashed in from the back face. Yup - some kind soul at one of the engineering shops thought it would be a great idea to remove a (relatively soft) brass timing gear with a hammer...

Tomorrow night is me and a dremel tool, to see if I can clear the burs, otherwise it is time to strip the crank. Again.

[Maybe]

Justin......

Go buy yourself a Jab3300 engine....and stop sukkeling! (or a Jab2200).
You will also have the comfort of knowing you've got a purposed made avaition fan in the front, leaving you to enjoy the flying and not worrying about what some other mechanic stuffed up deep down under in the old engine.

(I would have never lasted that long trying to sort out the VW. )

Come and let me take you for a flip in our Raven with the Jab2200 to see the performance of the Jab motors. From there all thats left to do is decide between taking the jab2200 or jab3300


Happy.....building!

[justin.schoeman]

Almost bought a 3300 engine the other day, but chickened out (old model which uses parts no longer manufactured, and coming up on 1000 hour service...)

Wish I had the money to buy a decent engine right now.

[justin.schoeman]

Managed to clean up the gear, but even though I taped up #3 bearing, I managed to get some dirt in. So time to strip the crank again and fit a new timing gear.

Hope I can do it without an engineering shop, or it is early holidays for me (until the engineers re-open).

[Jean Crous]

Justin, i am posting this here for "official" reasons, when your aerie is done (may that be soon) you owe me a visit here in Barrydale......no not by car
Best wishes for Xmas and new year
Regards
Jean

[justin.schoeman]

Justin, i am posting this here for "official" reasons, when your aerie is done (may that be soon) you owe me a visit here in Barrydale......no not by car
Best wishes for Xmas and new year
Regards
Jean

I will be there by March. Promise. Really...

-justin