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Corben Junior Ace Scratch Build.
- Thread starter Jim
- Start date
They're for the case through studs. Well, not exactly. The correct ones are out of stock. Those will just be temporary until I get the correct ones.
Con rods have been cleaned to within an inch of their lives...
Was very happy to see that these rods had been sent out and reworked. The bushings in the little end are new and reamed to new standards. Never even had a wrist pin stuck in 'em.
Went to check the big end clearance on the crank... and can't for the life of me figure out where I put the plastigauge... that I used just a few short days ago. Fuck me...
I'd pass that off to gettin' old, but I've done stuff like that pretty much my whole life.
The book calls for opposite con rods (it's a boxer) to be within 1/2 oz of each other. That's about 15 grams. Happy to report all 4 rods are within 2-3 grams of each other.
My plan was to have the rods on the crank, crank installed and the case halves back together before dark (yesterday). Not to be unfortunately. My local parts store has plastigauge... but they want 2-3 times as much for it as I paid on Amazon. Since this engine ain't gotta go fly tomorrow, I ordered more from Amazon.
As I was cleaning up, found a small bit of the plastic left over from doing the mains... about a half inch of the stuff. Enough to tell me the #1 con rod is between 2-3 thou clearance on the crank throw. book tolerance is .0005" to .006", so well within the book.
Considering I know the PO (my dad), I was sorely tempted to just call it good and put it all together... but nah, I'll wait. When this engine is done, I'll need to make a log book for it. Even though it's going on an experimental airplane and I don't have to, I intend sign this engine off as being built to factory specs using my A&P license number. In all my years of doing this, I've never lied on a log book signoff... not gonna start now. I'll wait and check all 4 rods
Was very happy to see that these rods had been sent out and reworked. The bushings in the little end are new and reamed to new standards. Never even had a wrist pin stuck in 'em.
Went to check the big end clearance on the crank... and can't for the life of me figure out where I put the plastigauge... that I used just a few short days ago. Fuck me...
I'd pass that off to gettin' old, but I've done stuff like that pretty much my whole life.
The book calls for opposite con rods (it's a boxer) to be within 1/2 oz of each other. That's about 15 grams. Happy to report all 4 rods are within 2-3 grams of each other.
My plan was to have the rods on the crank, crank installed and the case halves back together before dark (yesterday). Not to be unfortunately. My local parts store has plastigauge... but they want 2-3 times as much for it as I paid on Amazon. Since this engine ain't gotta go fly tomorrow, I ordered more from Amazon.
As I was cleaning up, found a small bit of the plastic left over from doing the mains... about a half inch of the stuff. Enough to tell me the #1 con rod is between 2-3 thou clearance on the crank throw. book tolerance is .0005" to .006", so well within the book.
Considering I know the PO (my dad), I was sorely tempted to just call it good and put it all together... but nah, I'll wait. When this engine is done, I'll need to make a log book for it. Even though it's going on an experimental airplane and I don't have to, I intend sign this engine off as being built to factory specs using my A&P license number. In all my years of doing this, I've never lied on a log book signoff... not gonna start now. I'll wait and check all 4 rods
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@Jim - Just saw this and read through. Very cool and good on ya for stepping out and following your dream; all the best to get it to where you want it!!
Have an old biker friend that is also into airplanes (inherited it from his father who built his own plane(s)). He has a clipped-wing Cub at present. Cheers.
Have an old biker friend that is also into airplanes (inherited it from his father who built his own plane(s)). He has a clipped-wing Cub at present. Cheers.
Plastigauge ordered on Sun evening, arrives Tue evening. Anybody remember the days when you ordered on the phone and it might show up two weeks later? Anyway... back to it.
Con rod #1 clearance was .0025" Side clearance measures .008" (tolerance is .006 to .012")... (previous comment)
Con rod #2 clearance is about .0035" Side measures .007"
#3 measures .003" Side clearance is .007"
Lastly, #4 measures .0025" Side clearance is .008"
Looking at the bearings, it looks like they were cleaned up with a grinder. They weren't, it's my damn Pixel phone camera... it picks up everything. They're new bearings that had dried up buildup grease on 'em. Stuck 'em in the parts washer and cleaned with a nylon bristle brush. Here's how they look from about a foot further away.
Anyway, everything measures good, so I gave everything another good cleaning and installed the con rods on the crank. Torque is 34 to 40 ft-lbs. Torqued all of 'em to 34 ft-lbs initially. Then set the wrench to 40 ft-lbs. Tried a cotter pin at each nut. I think 2 of 'em dropped. The rest I slowly crept up on without going over 40 ft-lbs. A bit fiddly, but eventually got cotters to drop in all of 'em.
Installed the three main bearing halves in the left case half and dropped the crank in.
It's well past 9 pm now and I still need to give the cam another good scrubbing before I install it and close out the cases. If only the Amazon driver hav been an hour earlier... anyway, called it for the day.
Con rod #1 clearance was .0025" Side clearance measures .008" (tolerance is .006 to .012")... (previous comment)
Con rod #2 clearance is about .0035" Side measures .007"
#3 measures .003" Side clearance is .007"
Lastly, #4 measures .0025" Side clearance is .008"
Looking at the bearings, it looks like they were cleaned up with a grinder. They weren't, it's my damn Pixel phone camera... it picks up everything. They're new bearings that had dried up buildup grease on 'em. Stuck 'em in the parts washer and cleaned with a nylon bristle brush. Here's how they look from about a foot further away.
Anyway, everything measures good, so I gave everything another good cleaning and installed the con rods on the crank. Torque is 34 to 40 ft-lbs. Torqued all of 'em to 34 ft-lbs initially. Then set the wrench to 40 ft-lbs. Tried a cotter pin at each nut. I think 2 of 'em dropped. The rest I slowly crept up on without going over 40 ft-lbs. A bit fiddly, but eventually got cotters to drop in all of 'em.
Installed the three main bearing halves in the left case half and dropped the crank in.
It's well past 9 pm now and I still need to give the cam another good scrubbing before I install it and close out the cases. If only the Amazon driver hav been an hour earlier... anyway, called it for the day.
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Case Closed!
Finished cleaning up the cam. Liberal amounts of buildup lube on the lifter faces and cam lobes, and installed the cam. Then went around the left case with a light smear of Permatex Aviation Sealer.
Let that tack up and ran two beads of silk thread around the case edges...
Light smear of sealant on the other side, reinstalled and lubed the main bearings.... lube on the lifters....
.... and reunited the case halves.
New hardware going in. Nothing's torqued yet, jus' snugged a bit. The lift point bracket is missing from the top row of case bolts. Not spendin' a kings ransom for a part that's only used to lift the engine on and off the firewall, I'll need to fab one. Most likely tomorrow. After that I can torque everything.
Funny quirk about these lil' connie's... There's timing marks on both the cam and crank gear, but nothing to align the gears to their respective shaft's. I mean seriously, what's the point of marks on the gears when the gears can mount in 4 different positions? The book says to align the crank at TDC on #1, rotate the cam so it's just closing the exhaust and opening the intake, align the marks on the gears... then press the gears in place with the 4 (ea) bolts. I mean... it works. As long as you're within 45°s you can figure it out from there. But really... would it be too much to put punch marks or a dowl... something to tell you where the gears align on the shafts?
Anyway, it's properly timed and bolts installed. Still need torque and safety wire.
That's it for now.
Finished cleaning up the cam. Liberal amounts of buildup lube on the lifter faces and cam lobes, and installed the cam. Then went around the left case with a light smear of Permatex Aviation Sealer.
Let that tack up and ran two beads of silk thread around the case edges...
Light smear of sealant on the other side, reinstalled and lubed the main bearings.... lube on the lifters....
.... and reunited the case halves.
New hardware going in. Nothing's torqued yet, jus' snugged a bit. The lift point bracket is missing from the top row of case bolts. Not spendin' a kings ransom for a part that's only used to lift the engine on and off the firewall, I'll need to fab one. Most likely tomorrow. After that I can torque everything.
Funny quirk about these lil' connie's... There's timing marks on both the cam and crank gear, but nothing to align the gears to their respective shaft's. I mean seriously, what's the point of marks on the gears when the gears can mount in 4 different positions? The book says to align the crank at TDC on #1, rotate the cam so it's just closing the exhaust and opening the intake, align the marks on the gears... then press the gears in place with the 4 (ea) bolts. I mean... it works. As long as you're within 45°s you can figure it out from there. But really... would it be too much to put punch marks or a dowl... something to tell you where the gears align on the shafts?
Anyway, it's properly timed and bolts installed. Still need torque and safety wire.
That's it for now.
Aren’t you going to polish those cases to a mirror like finish? 
Seriously, it’s pretty cool seeing that old engine go together. I like the little detail of the threads embedded in the sealant between the case halves.
Seriously, it’s pretty cool seeing that old engine go together. I like the little detail of the threads embedded in the sealant between the case halves.
Continental engines come in only one flavor... 
My dad got me my first folding pocket knife by mailing in some Beechnut Chewing Tobacco wrappers and $0.50
I ordered car parts from Honest Charley in Chattanooga via the mail and Post Office money orders
Spent countless hours pouring through a J C Whitney catalogue for parts to overhaul various engines. Fill out the form, go get a money order... lick the envelope and wait 3 weeks for parts to arrive.
Most times you could overhaul a V8 for about half what your local parts house wanted. And good quality too, no Chinese crap back in them days.
True. J C Whitney was my friend as well.
You must of bought from a different JC Whitney than I did...
But I guess you are right, back then it was Japanese Taiwan and cheezy American manufacturer's crap.
But even in Baraboo we had a GOOD independent auto parts store with a 6' foot catalog rack. Just thinking of them I can smell scorched iron and burned oil from the brake drum lathe and hydraulic fitting press. I still have tools and supplies I bought there. An engine shop, radiator shop, several wrecking yards.
Gambles, Western Auto, True Value, and Ace hardware stores. A small engine shop, tractor dealers, one for every major brand and a tractor junk yard. A machine shop that still had overhead belt line drive equipment.
A 40 minute motorcycle ride to the Big City (Madison) Japanese Motorcycle dealers with big parts departments. They all had counter guys that knew their stuff and often a cranky old owner that would share some knowledge if you were respectful.
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When my long gone cool old school local auto parts shop with the brake lathe and hydraulic hose machine updated their 6' catalog rack, I grabbed the old stack for my own home shop. Gotta say, those catalogs were the sh*t before the internet. I only recently finally turned them over to another hoarder. The illustrated catalogs for things like 4 Seasons (air conditioning/heater) were invaluable. But, "progress" is inevitable, and our local motorcycle shop (Pete's Cycle), a Honda and Kawasaki dealer since the mid 60's, was just recently torn down and some awful corporate chicken finger place is now on that corner. Dad bought both his bikes there, and I bought my first bike there. Nothing is forever, appreciate it while it's here.You must of bought from a different JC Whitney than I did...
But I guess you are right, back then it was Japanese Taiwan and cheezy American manufacturer's crap.
But even in Baraboo we had a GOOD independent auto parts store. Witha 6' foot catalog rack. Just thinking of them I can smell scorched iron and burned oil from the brake drum lathe and hydraulic fitting press. I still have tools and supplies I bought there. An engine shop, radiator shop, several wrecking yards.
Gambles, Western Auto, True Value, and Ace hardware stores. A small engine shop Tractor dealers one for every major brand and a tractor junk yard. A machine shop that still had overhead belt line drive equipment.
A 40 minute motorcycle ride to the Big City (Madison) Japanese Motorcycle dealers with big parts departments. They all had counter guys that knew their stuff and often a cranky old owner that would share some knowledge if you were respectful.
Just odds and ends gettin' us toward closing this engine up.
Ordered a gasket set that went backorder. Cancelled the order and started making my own...
Mechanical fuel pump mount pad cover plate.
Vacuum pump mount pad cover plate.
Crankcase vent elbow.
Pushrod tube adaptors.
There's a felt seal that goes over the rubber crank seal. Don't ask me why...
I was hunting through my scrounge earlier for something unrelated to this engine and ran across a hanger bracket. It's a little pitted, but considering it's 1/8" 4130, it's still strong enough to lift 4 C-85's at once. In closely cowled installations we always removed 'em so there's no chance of interference between the two, so I prolly have a bag full of 'em around here somewhere.
That's it for now.
Ordered a gasket set that went backorder. Cancelled the order and started making my own...
Mechanical fuel pump mount pad cover plate.
Vacuum pump mount pad cover plate.
Crankcase vent elbow.
Pushrod tube adaptors.
There's a felt seal that goes over the rubber crank seal. Don't ask me why...
I was hunting through my scrounge earlier for something unrelated to this engine and ran across a hanger bracket. It's a little pitted, but considering it's 1/8" 4130, it's still strong enough to lift 4 C-85's at once. In closely cowled installations we always removed 'em so there's no chance of interference between the two, so I prolly have a bag full of 'em around here somewhere.
That's it for now.
You once commented on me not wasting too much gasket material! Nicely done, Sir.
That's the beauty of operating under the "experimental" category- no need to buy high dollar "certified" parts (like standard gaskets) where they really aren't necessary. I once made a thermostat gasket out of a paper plate on the side of I81 somewhere between Luray and Roanoke, worked fine on the old Chevy 250 6 banger. Are you familiar with the crankcase vent mod intended to reduce oil loss via the vent tube? Basically, a perforated tube extends into the case to break up/alter the flow so less oil is vented. I can probably find a file with the details. The other trick, apparently, is to run the vent tube/hose over the top of the engine vs. straight down and under. My C85 has a spin on oil filter modification, so my actual oil quantity is about a qt. more than what is shown on the dipstick- I'm still sorting out the "happy place" for oil level that doesn't result in so much being blown out the vent and all over the belly.
