Building a VW Aero-Engine

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Pops

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In building this engine I ran into a problem I have never had. In putting the case together, when still opened about 1/2" the crankshaft would not turn. Always make sure the crankshaft will freely turn while you are putting the case together . Common problem is not having one of the bearings in the location pins. Check pins, OK, Tried again, same problem. Check pins, OK. After a lot of headaches, I found the problem. I bought a set of new main bearings and after a lot checking, found the size of the bearing in the box was mixed sizes. The #2 bearing, ( crankshaft center main bearing in two halfs), was an oversize OD that is made for case lined bored engines. The bearing was .020 oversize OD. for my case. The unopened box was marked correctly for the size. But, the one bearing was wrong.
Found this information for the bearing sizes of ID and OD. Hope you never have the problem, but if you do, you will need this information. Would be a good practice to check your bearing measurements to make sure you have the correct ones before trying to put the case together. Wish I had.
 

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fly2kads

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I bought a set of new main bearings and after a lot checking, found the size of the bearing in the box was mixed sizes. The #2 bearing, ( crankshaft center main bearing in two halfs), was an oversize OD that is made for case lined bored engines. The bearing was .020 oversize OD. for my case. The unopened box was marked correctly for the size. But, the one bearing was wrong.
I recall reading on the VW forums at The Samba that other people have had that same issue. Someone mentioned shaving the OD of the center main bearing down to fit the case. I did a quick search there, and couldn't find that thread. If I find it later, I will post the link here. At any rate, apparently you're not the first person to encounter that.
 

Vigilant1

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The unopened box was marked correctly for the size. But, the one bearing was wrong.
How annoying, sorry you had to do all that investigation and re-work, Pops. I guess a customer needs to mic every part to be sure it is the right one. And if you just ordered by part number, you'd have to look up the spec for that part to know if you got the right one.
Really ridiculous.
 

Waltcloudt

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Pops,
I'm a newbie but I attended a seminar at Airventure 2021 on the VW 1/2 engine and saw one on an ultralight. I started reading this thread but your videos are not available here. Where are they available?
 

Baron Von Tygart

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Oh yes, building up or overhauling an aero-conversion engine can be a frustrating experience. Semingly insignificant differences in after-market parts from a variety of vendors can be a real problem. By the way - for anyone interested in building or overhaul, I have 3 recently operational aero-conversion cores available , free for pick-up @ 37FL.
 

Pops

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There are some good quality VW engine parts on the market and there are some junk VW engine parts on the market. Its nice that you can order your engine parts from people like Great Plains and Scott Casler at Hummel engines were they have weeded out the junk parts for you.

I'm fortunate in there is a VW only parts and mechine shop business about 40 miles from me that I have been dealing with since the 1970's. They do great work. They also do mail order. At one time they had the worlds record holding VW powered dragster. They know VW's.
 

Pops

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Found where I wanted to mount the alternator today. ( 12V x 14 Amp) 3 LB. Need to make the belt tension arm and I used a belt that I had to measure for the length of belt that I need,-- 27" long. Next will be mounting the mag mounting ring with standoffs. Need Zero runout of the mag coupling for no wear.
Do you wonder why I have an old distributor mounted in the case ? When putting the case together, It's easier to install the distributor drive with the 2 shim under the bottom before laying the crankshaft in the #3, #4 side of the case. If you wait until the engine is together Its hard to install the drive without dropping the two shims down in the case. Yes, I know you can use a length of wire and put bearing grease on the shims and drop them in place. Then you hope you can install the distributor driveshaft without the shims falling down inside of the case and try to fish them out with a magnet.
If you install the dist drive first , you have to install a dist so when you turn the crankshaft the dist drive doesn't move up and loose the shims. Drop an old dist in the hole and no worries while turning the crankshaft checking for any binding as you torque the nuts on the case half's.
 

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Pops

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Made the mag mounting ring standoffs. Have the alternator completely mounted. Now I have to turn an aluminum center plug to position the mounting in the dead center of the crank . The mag coupling is dead center or will use the center hole for the alum aliment plug. Once in position I will drill and tap for bolts to the standoff's. Picture of the cardboard pattern for an alum dirt and oil cover for the mag coupling.
I can't use my VW Slick mag because its a right turning impulse mag and will need a left impulse mag as used on the Lyc- 235- 290- 320's with the 25 or 30 deg lag.
Picture of the 10 mm lower spark plugs in the single port heads.
 

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Pops

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This flywheel drive engine is 4" longer than the engine with the prop on the pulley end and the mag on the flywheel end. I know its going to be a little heavier (darn ), and may require me to move it closer to the firewall to put the W&B were it was before. If so, I might have to cut a hole in the firewall and put a small box for clearance of the end of the mag and plug wires. Will start looking for a small alum or stainless cooking pot about 6"or 7" in dia and 3 or 4" deep in case I need it. IF not, I can use it to make some "Mater soup" on the wood stove in the hanger. :)
 
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Reading your post #141 I remember the 1st time I put the case halves on a Revmaster. It wouldn't go together, being propped open at the thrust bearing end. As you said ALWAYS check that bearings are located on their alignment posts. Crankcase developed a crack in this area shortly after!
 

Pops

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Reading your post #141 I remember the 1st time I put the case halves on a Revmaster. It wouldn't go together, being propped open at the thrust bearing end. As you said ALWAYS check that bearings are located on their alignment posts. Crankcase developed a crack in this area shortly after!
First VW engine that I built in about 1970, I did the same thing. Very common mistake. Then I started to dry fit the bearings in the pins and then mark the outside shell of the bearing at the case parting line with a fine line felt marker to make it easier to get the bearing on the pins when installing the crankshaft in the right case half. Built VW engines as a side business for several years until the business grew and I didn't have time to do both jobs and get any sleep. So, I kept my day job.
 

karmarepair

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Will start looking for a small alum or stainless cooking pot about 6"or 7" in dia and 3 or 4" deep in case I need it.
Candidates: Camping aluminum cook pots, home use stainless steel mixing bowls (Bingelis covers this), aluminum kitchen storage containers. You can even get titanium backpacking cook pots if you want to get fancy...but outside the Goodwill in Missoula, MT, I don't think you'd like the price.
 

Vigilant1

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It would seem that a nice flat flanged rim at the top of the bowl would make it easier to affix to the firewall. The dog bowls typically have a rim like that.
 

karmarepair

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Stainless steel dog food bowls have a nicer shape for things like this. Kitchen bowls are generally too rounded......IMHO
This happens to be a CAT bowl, but I see your point https://www.amazon.com/dp/B07G6QQBDH/ref=syn_sd_onsite_desktop_6?psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyVUhWSUM2TkNDQk45JmVuY3J5cHRlZElkPUEwMjI4MjM3TFRITlUwUTRTTFlMJmVuY3J5cHRlZEFkSWQ9QTAzODE4MzczRjQxVERJWDQwSFVGJndpZGdldE5hbWU9c2Rfb25zaXRlX2Rlc2t0b3AmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl

Some mixing bowls are roughly spherical, others have more vertical sides, like so:


Me, I prefer Stainless Steel or galvanized for firewalls over aluminum, but I haven't seen too many accident reports of FWF fires where such a distinction would have made much of a difference.
 

Pops

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The dog and cat bowl look just right. But, If I buy the other set of SS bowls , I can give my wife the ones I don't want and get some points. :)
 
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