Corben Junior Ace Scratch Build.

[Jim]

Are you familiar with the crankcase vent mod intended to reduce oil loss via the vent tube? I can probably find a file with the details.

Yes please!
I'd also like to see pics of your filter mod if possible. I'm gonna do a filter mod on this engine. Having screens is good enough for an XS, I'd prefer a bit more for this engine.

 

[Jan_P]

Yes Sir
Some question if allowed maybe dumb ones

Why are the bolts Yellow for closing the cases ?
When using the plastigauge is it tightened to the spec or is that not necessary ?
Seen it in Honda Motorcycle engines manuals.
Any tightening pattern cases ?
The Silk threads please tell more about that Never heard of that before. Given the correct material perhaps that can be used at other places.
How is lubrication ensured fex in a dive .. or upside down flying

 

[Jim]

Yes Sir
Some question if allowed maybe dumb ones

Why are the bolts Yellow for closing the cases ?
When using the plastigauge is it tightened to the spec or is that not necessary ?
Seen it in Honda Motorcycle engines manuals.
Any tightening pattern cases ?
The Silk threads please tell more about that Never heard of that before. Given the correct material perhaps that can be used at other places.
How is lubrication ensured fex in a dive .. or upside down flying

Yellow is the cad plating.
Torque to spec when checking with plastigauge.
Yes, a specific pattern to torque the cases.
The silk is called for in the manual. Lycoming and Franklin also do the same. I also use silk on VW and Corvair engines.
When inverted you lose the pressure lubrication and revert to splash lubrication. The crank uses plain bearings that don't much like splash lube, so inverted flight isn't recommended.
There's a few companies that make a bolt on inverted oil system if you're planning on hard aerobatics (I'm not).

 

[Pat D]

Yes please!
I'd also like to see pics of your filter mod if possible. I'm gonna do a filter mod on this engine. Having screens is good enough for an XS, I'd prefer a bit more for this engine.

While there is a factory part, most experimental folks just make one- the .pdf has the details. I don't know if my engine has it or not, I'm not inclined to unscrew the fitting and see- I see too many folks cracking their cases or developing cracks around the tapered NPT plugs. As noted, if I keep the oil level where things are "happy", I don't get nearly as much oil on the belly.

 

[Jim]

We be accessorized...

Torqued and safetied the crank and cam timing gears.

Made the gasket for the accessory drive case.

Cleaned up the case and oil pump bits...

 

[Jim]

Well this is odd...

Went down to the shed to retrieve the jugs. I could have swore I had 7 of 'em. 5 was all I could find.
Making 4 good out of 7 was a lot better odds than 4 out of 5. Oh well. On the bright side, 3 of 'em have tags showing the bore and guides are within book callouts, so I should be able to make at least 3 good ones. That leaves 2 to make the last one. Should be doable. At least I hope so. New ones go for north of 2k nowadays.

Time for more cleaning and measuring...

 

[Pat D]

Are you going with the stock pushrod tubes, or the aftermarket ones that can be removed to replace seals w/o pulling the jug? Fortunately, only one of my pushrod seals leaks, and if I keep after it, the engine stays clean. Convenient that it's one I can get to!
https://realgaskets.com/product/pushrod-tube-seal-kit/

 

[Jim]

Are you going with the stock pushrod tubes, or the aftermarket ones that can be removed to replace seals w/o pulling the jug? Fortunately, only one of my pushrod seals leaks, and if I keep after it, the engine stays clean. Convenient that it's one I can get to!
https://realgaskets.com/product/pushrod-tube-seal-kit/

I'll prolly go with the aftermarkets... 500 bucks is a bit much though. Still undecided. If I had a new one in hand to dimension, I could prolly make 'em.

Still up in the air.

 

[Downeaster]

Still up in the air.

How are you managing that with no motor?

 

[Jim]

How are you managing that with no motor?

Freestyle levitation?

 

[grouchie77]

How are you managing that with no motor?

Not for long I'd bet.

 

[Jim]

While there is a factory part, most experimental folks just make one- the .pdf has the details. I don't know if my engine has it or not, I'm not inclined to unscrew the fitting and see- I see too many folks cracking their cases or developing cracks around the tapered NPT plugs. As noted, if I keep the oil level where things are "happy", I don't get nearly as much oil on the belly.

So... decided to do the crankcase breather mod. Diggin' back in the cobwebs, I remember doing these a time or three. No reason not to do my own.

The mod calls for either steel or brass tubing, neither of which I have on hand. I do have 1/2" copper though... close enough. Used a step drill to enlarge the ID of the AN fitting. Made for a good snug fit.

EDIT: Just reread the instructions, always a good idea with airplanes.... calls for brass, steel or copper. So my copper tube is per the instructions.

Cut a copper tube longer than needed, cleaned everything up... put a depth mark on the tube and silver soldered the tube in place.

And here we are. Cut the tube to 2-3/4" per the bulletin, cleaned it up again and reinstalled.

Here's the Service Letter from Pat's PDF above that I followed.

 

[Jim]

Mailman popped by...

Two intake manifolds. Still need two more.
Cost added to comment #1

We'll get there...

 

[Pat D]

Mailman popped by...

Two intake manifolds. Still need two more.
Cost added to comment #1

We'll get there...

View attachment 362851

Gonna take some polishing to get 'em as shiny as mine! That said, I cannot imagine the mindset that determined investing in chrome plated intakes, intake runners, oil tank and valve covers was a worthy allocation of funds.

 

[Jim]

I'll probably spring for the chrome valve covers... The rest is just over the top.

 

[Jim]

Ran across an Ebay ad a few weeks ago for 6 C-85 pistons for $190. Ad said they were used but in good condition, but the pics looked like they were new pistons. Decided to roll the dice.

Mailman delivery... My suspicions were correct. All 6 are NOS pistons. Hell, they still have the (inked) part number stamped on 'em. OF the six, five look to be usable. For reference, new aftermarket pistons go for north of $200..... each!

Color me surprised as hell.

EDIT: added to page one tally.

 

[Mailman]

Mailman delivery... My suspicions were correct. All 6 are NOS pistons.

Score!

 

[Jim]

Score!

'Bout time I won an Ebay bet, eh...

 

[Jim]

With a little luck, I'll have 5 serviceable pistons.
Only need 4, so I'll put the extra up on Ebay for about a hundred bucks and recoup half my funds.

 

[halfmile]

Here`s some inspiration. Not that you would ever need it.
https://www.facebook.com/watch/?ref=saved&v=836090215801816