Building a VW Aero-Engine

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Pops

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I have made the trip from California to Oshkosh in my VW powered motorglider and can share some real world experiences of operating this engine and working on it to keep going during the trip. Lead in Avgas caused major problems. You can find my trip report at caro-engineering.com on the "News" page.
Good read, thank you.
 

Hawk81A

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Wonder if it would help running oil through a length of copper tubing coiled around part of the intake would help. I noticed long ago that some of the Continental or Lycoming (don't remember which) had the carb mounted to the bottom of the oil sump and individual cylinders feeding from the sides. guess the hot oil helped with atomization. I remember in my old Corvair days running a turbo manifold and the Carter side draft carb without the turbo. It would ice up where the mixture flowed through the gutted turbo housing (didn't have the heat of the exhaust turbine). Dennis
 

BJC

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MAP:

Enjoyed your trip log.

Some years ago, my daughter and I flew part of your east bound route - Logan to Cheyenne - in January, with tail winds from 42 to 60 knots the entire way. The winter time scenery was really interesting to us. We live in the SE. The people in Logan were really nice. We were there for two days because of freezing fog.

Paul’s flying club concept is interesting. He is doing something that, hopefully, will make flying in remote areas more accessible.

Sorry about your engine problems. But it sounded like a great adventure in spite of the engine.

Any plans to do anything with the engine?


BJC
 
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Marc W

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Wonder if it would help running oil through a length of copper tubing coiled around part of the intake would help. I noticed long ago that some of the Continental or Lycoming (don't remember which) had the carb mounted to the bottom of the oil sump and individual cylinders feeding from the sides. guess the hot oil helped with atomization. I remember in my old Corvair days running a turbo manifold and the Carter side draft carb without the turbo. It would ice up where the mixture flowed through the gutted turbo housing (didn't have the heat of the exhaust turbine). Dennis
Scott Casler runs hot oil through aluminum tubing wrapped around the intake for his 1/2 VW conversions. 7' of 5/16" tube if my faulty memory serves.
 

Marc W

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This would also make one question the GPASC manifold top casting. That manifold design does not split the flow until just prior to the final curve into the head.
In fact there has been one experiment posted on the web where the center divider was removed and mixture distribution improved. I tried it on my 2180 but the engine had other issues which disguised any improvements in my engine. Discussion here: Intake Manifolds
 

Vigilant1

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I have made the trip from California to Oshkosh in my VW powered motorglider and can share some real world experiences of operating this engine and working on it to keep going during the trip. Lead in Avgas caused major problems. You can find my trip report at caro-engineering.com on the "News" page.
Thanks for the write-up. You had quite a trip.

I've normally burned 100LL in my VW based aero engine. I haven't had the ignition problems you experienced, but have had considerable (yellow) lead buildup inside the combustion chamber and have had one case where the buildup caused an exhaust valve to not close (with subsequent heat damage to that valve and seat).
Once I'm flying again I plan to seek out and use ethanol free auto fuel for my local flying. For cross country trips where I must use 100LL, I'll add Decalin or TCP to try scavenge the lead, at least to the extent possible.
Plugs/threads: Some people go ahead and install Time-sert or similar steel inserts into the spark plugs holes right from the start (when the heads are new). I don't know for sure if that's the best answer, but I can appreciate the rationale for it.
Thanks again for the report!
Mark
 
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delta

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I have made the trip from California to Oshkosh in my VW powered motorglider and can share some real world experiences of operating this engine and working on it to keep going during the trip. Lead in Avgas caused major problems. You can find my trip report at caro-engineering.com on the "News" page.
I wonder if the next hottest plug and a little more gap might help. You could run it by Limbach first, but that's the first thing I'd try. Hopefully you'll have a much more pleasant trip next year...
 

Pops

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Having sold used VW's for several years the most problems found is burnt exhaust valves ( mostly #3 for a reason) , stripped spark plug threads, worn out clutch, and timing and dwell wrong, ( poor tuneups). All of that is just lack of proper maintenance.
 

Map

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I made the trip with the long wings, as you can see in some pictures.
I have installed two spark plug steel threaded inserts when they were stripped, but there are several potential issues with this. First of all it is difficult to do it right, the potential is there to screw it up and ruin the head. Second is to keep the inserts in. I have had a version in the past that had sort of a mechanical lock that worked quite well, but have not found them for sale anymore. On the ones I have I used high temperature thread locker, which does not work as well, I had one insert come out and bonded it in again. Then the spark plug may also get 'sort of' stuck in the insert, and getting it out can also loosen the insert. My advice on that is to not put inserts in up front, but carry the tools to install one on longer trips along, and know exactly how to use them.

The plugs are used are the ones specified by Great Plains (my engine version). I think part of the problem was flying at high altitude over the mountains and not having a mixture control to lean it, so my EGT's were pretty low most of the time.

I may try TCP next time (I used it for a while in the Pulsar, the Rotax 912 had similar issues), but it only is supposed to make the deposits non-conductive so that it does not shorten out the plugs as easily, but the deposits will still build up.
 

TFF

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Low compression engines don’t usually like 100LL. It’s one of the reasons Lycoming started making the 160hp O320. The 150 hp versions had lead issues like the 235 because they were meant for red gas.

The timeserts are usually pretty good at not coming out. If the hole got too big oversize are available. One thing if the head is off is to mill the chamber side flush so it doesn’t become a hot spot. I have had one installed where the timesert was milled slightly and the hole not through the chamber. The combustion chamber didn’t see anything different at the tip of the plug
 

Pops

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I had spark plug inserts installed in several heads by a machine shop. They have a flange on top with a slot in the side of the flange for a locking pin into the head. Been using then for 20 years. Never any problems. I don't know the name. The shop charged $25 set up and $17 for each insert and they supply the inserts the last time I had a set of heads done.
Marietta Ignition Machine Shop, 321 Second St. Marietta, Ohio.
740-374-6758
I have never had any problems with the mixture when using the Zenith carb. But in WV the highest mountains is around 5K, but very rough. Have flown the SSSC to just under 10K and the engine ran fine. In all the years I adjust the mixture screw 1/2 turn between winter and summer. Adjust in the month of May and Oct. Also remove the side flip up windows and lock the door bottom down for the summer in May. Cost about 3 mph in cruise. Think I read somewhere the Zenith is designed to adjust for altitude, don't know for sure.
 

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delta

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I guess I'm missing how a long reach plug fits in a type one head. I didn't know that great planes sells a type 4 conversion.
 

Pops

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This is from Great Plains engine assembly manual. Steve recommend changing the position of #1 cylinder and changing the firing order from 1432 to 1234 when using a mag. I don't think he ever says why, but I did it back in 2006. With that change when you check the valve adjustment, it makes it simpler and easier. Bring the new #1 to TDC and check the valve lash. I do like Steve's instructions, tighten the screw down on a .008 feeler gauge and pull it out and insert a .006 and it should be loose, and a .007 will be just right. I know some people uses .004 but the gap tends to tighten up with use and this gives a little more time before getting to tight. Maybe a very tiny loss in power, but nothing you can tell.
Got #1 checked and recorded, now just turn the prop to the new #2 TDC next door. No need to go to the other side of the engine as in the old way. Now check #2 and install the valve pan and bale with a screwdriver. Now go to the other side and do the same, turn the prop and #3 will go to TDC and check the clearance and turn the prop and #4 will go to TDC and check it. Install the valve cover pan and you are done. Be sure to record all gap you found before adjustment and check at the next 25 hr check and see if there is any cylinder that has a trend of the adjustment tightening up.

Wish Steve Bennett was still with us.
 

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Vigilant1

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Wish Steve Bennett was still with us.
Amen. Not many folks have the combination of VW knowledge, aviation experience, integrity, business sense, and an interest in running such a business as their livelihood. We were lucky to have him and we're still benefitting from the work he did.
 

Pops

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I met Steve at Oshkosh many years ago and he seemed like a very nice person. Talked on the phone many times and he always was ready to help and give advice. Yes, very lucky and is missed. People like Steve leaves the world a better place and then there are those that do not.
 

thisadviceisworthles

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I just found this thread, as I am investigating a VW rebuild. Even without the videos there is some great information.

@Pops are the videos posted anywhere else, it seems they no longer exist at the Youtube links in the thread.
 
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