Justin's Raven

Aircraft Projects Underway or Completed

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justin.schoeman
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Re: Justin's Raven

Postby justin.schoeman » Mon Jul 20, 2009 8:59 pm

Tipsy Flyer wrote:Hi Justin,
Sorry to hear about your engine troubles.
How many hours has this engine done ?
What type of aircraft was it's original "home"
Carb or injected
Hows the bottom end looking ie case, crank, cam, follows etc
Regards
Glen
The engine has 90 hours on, and is carburetted. It was in a standard Raven (long wings) previously. I haven't opened the crank (yet). Don't want to play with that, if it is not necessary.

Crank end float measures 0.006". I can't feel any play on the crank, or rods (not that that is a great indicator), and the oil is clean (magnet hasn't picked up anything in the drained oil).

I have the AP coming around tomorrow afternoon, and will get his opinion. It may well be the best bet to open up the bottom end, and check...
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Re: Justin's Raven

Postby Tipsy Flyer » Mon Jul 20, 2009 9:29 pm

That's not many hours at all, best to strip and inspect every little thing yourself. The only person you can trust....is your self vhpy
Was thinking about, what appears to be (possible) uneven mixture distribution via the inlet manifold, if one made temp short exhaust stubs and used an automotive gas analyzer and check each cylinders mixture from idle to top end. I know of someone who has uneven mixture problems with an 1835cc conversion using a ellison throttle body. The aerovee carb is much the same as the ellison.
Not possible that this is caused by overheating, i wonder how well the original baffets fitted, vw's need lots of cool fresh air and baffles in all the right places vhpy
Glad to see you have come right with the doors
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Re: Justin's Raven

Postby justin.schoeman » Mon Jul 20, 2009 9:44 pm

Tipsy Flyer wrote:That's not many hours at all, best to strip and inspect every little thing yourself. The only person you can trust....is your self vhpy


I am beginning to realise that...
Was thinking about, what appears to be (possible) uneven mixture distribution via the inlet manifold, if one made temp short exhaust stubs and used an automotive gas analyzer and check each cylinders mixture from idle to top end. I know of someone who has uneven mixture problems with an 1835cc conversion using a ellison throttle body. The aerovee carb is much the same as the ellison.


This engine has a Stromberg on. Much better atomisation than the aerocarb, and generally good mixture distribution.

3 cylinders are sooty black, and only 1 looked 'good', and that was the one with detonation. I am not sure if the carbon was burnt off, or if this one cylinder really ran lean.
Not possible that this is caused by overheating, i wonder how well the original baffets fitted, vw's need lots of cool fresh air and baffles in all the right places vhpy
The original baffles were pretty cr@ppy. Didn't seal well, and had many holes. I am making the new baffles out of fibre glass, and high temperature resin. I will mould them directly on the engine to ensure perfect sealing.
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Re: Justin's Raven

Postby Boet » Tue Jul 21, 2009 9:15 am

Saw the chain dangling, could not resist yanking it :lol: :lol: :lol: Justin, it is very important that you use ALL the cooling air going thru the engine fins for cooling. Leaks and ill fitting baffeling kills air cooled engines. If you are interested, I took some nice pics how I did it on the vollas we fitted to the BB`s. vhpy Will be glad to be of assistance.
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Re: Justin's Raven

Postby justin.schoeman » Tue Jul 21, 2009 9:33 am

Boet wrote:Saw the chain dangling, could not resist yanking it :lol: :lol: :lol: Justin, it is very important that you use ALL the cooling air going thru the engine fins for cooling. Leaks and ill fitting baffeling kills air cooled engines. If you are interested, I took some nice pics how I did it on the vollas we fitted to the BB`s. vhpy Will be glad to be of assistance.
Please do send them! (justin at schoeman dot org dot za).

I have stared at those cylinder heads long, and hard, and think I have some good ideas. Problem is, ideas don't mean squat when compared to experience...

Thanks,
Justin
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Re: Justin's Raven

Postby grostek » Tue Jul 21, 2009 9:42 am

Mooi asseblief aan Boet,

Please post the pics here so that we all can see and learn from them.

Kind regards,

Gunter Rostek.
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Re: Justin's Raven

Postby Tailspin » Tue Jul 21, 2009 10:19 am

Yes OOM BOET

Us poor Pilots that need to do everything our selfs are very willing Learners.
AS sum Blief OOM ^*^^ ^*^^ ^*^^
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justin.schoeman
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Re: Justin's Raven

Postby justin.schoeman » Tue Jul 21, 2009 6:01 pm

:evil: :evil: :evil:

Just had the AP over, and he pointed out the cracks that I didn't notice before. All four combustion chambers cracked across between the two valve seats. Two of them through the valve seats too.

He is of the opinion though that the owner has to have known the engine was damaged, so I suppose I should call the seller and negotiate a bit. Although I am not a person who likes picking fights... (**)

As to the crank, the AP recons it is not likely that there are any problems, but it would be a very good idea to open up and inspect anyway. I suppose I will get my hands dirty tonight.
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Re: Justin's Raven

Postby Boet » Tue Jul 21, 2009 7:40 pm

Justin, I have had this kind of situation too. I sold an engine (CHEAP) for, and on behalf of a client. I was not aware of any problems with the engine. The outjie who bought the engine, phoned me about a week later. Problems. Oom Boet, die enjin het sy no1 big end bearing geslaan. EEEEEISH. I phoned the owner of the engine, and explained the sorry situation to him, and without any bickering he gave the buyer 1/3rd of his money back. I very nice gesture indeed. But then we were not all born nice...........

By demand, I will give you guys a couple of my VW installation pics. If it can help and make someone`s flying safer, I will be very happy.
Attachments
baffeling VW 1.JPG
baffeling VW 1.JPG (31.26 KiB) Viewed 3523 times
Baffeling VW2.JPG
Baffeling VW2.JPG (32.92 KiB) Viewed 3523 times
Baffeling VW3.JPG
Baffeling VW3.JPG (30.21 KiB) Viewed 3522 times
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Re: Justin's Raven

Postby Boet » Tue Jul 21, 2009 7:43 pm

and sum more.. mutch-mutch moore.
Attachments
Baffeling VW 4.JPG
Baffeling VW 4.JPG (31.42 KiB) Viewed 3521 times
Baffeling VW 5.JPG
Baffeling VW 5.JPG (42.73 KiB) Viewed 3521 times
Baffeling VW 6.JPG
Baffeling VW 6.JPG (43.34 KiB) Viewed 3521 times
justin.schoeman
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Re: Justin's Raven

Postby justin.schoeman » Tue Jul 21, 2009 8:01 pm

Dang, that looks good. I think boet is a master of aluminium, as well as 'lap-en-pyp'!

Not a drop of cooling air wasted on those baffles. One question though - why are your back-side baffles (under the engine), not pressed against the fins, as some people recommend? I see a lot of baffles are made this way, but all the articles I can find say that it should be against the fins (so that no air escapes, unless it has passed between the fins.

Thanks,
Justin
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Re: Justin's Raven

Postby grostek » Tue Jul 21, 2009 9:17 pm

Thanks Boet,

Thanks for the pics, very neat installation, no air is wasted there.

What is the highest number of hours achieved on an engine with your cooling baffles before the heads needed a valve job.

Kind regards,

Gunter Rostek.
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Re: Justin's Raven

Postby Boet » Wed Jul 22, 2009 11:30 am

Unfortunatelu i never took a proper picture of the backside of the cyl`s, but I have done the same thing there. The air flows AROUND the cylinders, not just through them. Unfortunately these engines, by the way it was put together ....... :evil: :evil: :evil: :evil: :evil: :evil: .......... al kakked long before they developed any other problems. Highest time one was about 150hrs with no valve troubles. Why you ask?? vhpy
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Re: Justin's Raven

Postby grostek » Wed Jul 22, 2009 1:51 pm

Hi Boet,
Leaving assembly out of the equation, which should be done correctly but seldom is done correctly as witnessed by engines that kak before they have time to develop other problems, I asked because if your baffling system had run 1000 hours on a VW conversion it would prove how effective it is.

As it is in the pics, your system looks better than most I have seen.

Was just curious.

Kind regards,

Gunter Rostek.
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Re: Justin's Raven

Postby justin.schoeman » Wed Jul 22, 2009 9:43 pm

I was thinking of something like this (shamelessly stolen from schmelf on sonerai.net):
IM000860.jpg
Any air the enters the baffle must leave through the fins. These guys race formula-V aeroplanes, running flat out at 4500rpm for the duration of the race (making around 100hp).

Admittedly, they have a 200mph air stream to help with the cooling...

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