Valve Problem

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Mike Stewart

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Oct 11, 2010
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San Diego, CA
Give the company a call. The website prices are scary. Next time I'm at the hangar I'll get what I paid off the receipt and it's been a while but I'm sure I didn't pay over $300 for a pilot and two cutters and case.

I haven't watched that video in a long time so don't know what all it shows. I stand by my experience using the cutters and it was not at all difficult or tricky. I'd never done it before and it was straightforward and easy and came out perfect.

VW valve seats are notoriously soft. Read Bob Hoover.
 

Mike Stewart

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Oct 11, 2010
Messages
67
Location
San Diego, CA
Sorry for the poor resolution on this photo - I've been saving it for just the right time to send it to someone. It's too painful to look at at any closer detail in any case.

The punch line that goes with it is something like "If your top end doesn't look any worse than this one then you can buff this out and keep going." Or something perhaps more clever. At any rate, it's a photo worth sharing.

The valve construction (if you can make it out) is especially interesting. It's another good example of just how robust these old VW's are. This particular one had been in the plane and running fairly frequently for many, many years before this sudden surprise one Sunday morning flight.

I've been to the hangar and deeply explored my TOH box and although I couldn't find the original invoice for the Neway items I bought, there's enough there to make my point that - even though it's been nine years - I can't believe prices have gone to such a ridiculous level as what's on their website. I'll send this stuff along shortly for your interest.


Chugger.jpgChugger.jpgChugger.jpg
 

lakeracer69

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Dec 10, 2008
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146
Location
New Hampshire
Would it matter. ....the broken valve is steel
My question has nothing to do with the valve so no it doesn't matter. I'm asking another question as I'm starting to build a VW engine. I see a fried piston there, it's a question. Does every thread you read stay on track?
 

Pops

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When I was going about 75 or 80 mph on the interstate when a valve head broke off did a lot more than a flesh wound. Left 1/2 of the engine in parts on the interstate. Engine locked up with the rear wheels. Came close to swapping ends. Glad no one was close to me. Carb, Alt, and dist was usable.
 

don january

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Sure wasn't much left of that engine. Biggest problem I seemed to run into in a VW powered spray coupe was one over heating and points seemed to have a mind of their own. Also that bushings on the front of the starter didn't like to last long but there was a fare share of shutoff and start going on.
 

TFF

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Apr 28, 2010
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Memphis, TN
I keep the head of the first valve I broke from my high school car. 390 Ford I put a big cam in. Probably 100,000 miles on the engine. Valve stuck open during break in. When the cap on the rod broke in half it kicked the rod through the side of the block so far that it it never contacted the crank again loping on 7 cylinders.
 

Mike Stewart

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Joined
Oct 11, 2010
Messages
67
Location
San Diego, CA
I finally took time to open my TOH box at the hangar and find my receipts. I had a nice orderly folder in there with all the paperwork except . . . no original receipt! I'm attaching pictures of what I do have. Hopefully there's some pictures of interest amidst them. I bought my Neway cutters in 2009 so a good ten years ago but even so, it's hard to imagine that prices are three times higher now than they were then. I'll again suggest that you call the company and talk to (hopefully) the helpful person I spoke with at the time. The receipt from Neway you'll see among the pictures is for a replacement cutter head - looks like one of the two heads they sent me was the wrong one so the receipt is showing that I sent one back in return for the one I needed. Price per cutter head you'll see is $101. One cutter head is good for cutting two angles by adjusting the blades on the head. The second cutter head (if I'm calling these things by their correct name) is for doing the third angle.

Why I've got two pilots I can't remember - I suspect the rep I talked to assumed that I would have worn guides and so he included a pilot slightly larger than my actual guide inner diameter. I wish I could remember all of this more precisely. What I do remember clearly is that I didn't spend more than $300 for everything. There may be some other reason why I've got two pilots and am just so far removed from 2009 that I can't remember. It's possible a machinist friend gave me the extra. As I recall, I didn't need the second pilot - my guides were (amazingly) like new . . . amazingly I say because the engine had almost 500 hours on it when I had my broken spring issue. A little soot on the combustion chamber ends of the guides but wear was non-existent - a fact I attribute to Steve Bennett (from whom I bought the engine and plane) having the good sense to install elephant feet (swivel feet) on my rocker arms. They make a world of difference in preventing guide wear. I can't imagine why Continental and Lycoming don't use them but there must be a reason. The cynic in me would guess that their engines would last a lot longer without needing new parts if they built them with swivel heads on the tappet arms. Naaa . . . can't be that:rolleyes:

Some history on my engine. I had a valve spring break when I was at 10.5 over the Tampa TCA. I thought I'd swallowed a valve. The engine continued to idle very roughly so I didn't shut it down although in retrospect it would have been a wise thing to do since if it had been a broken valve and if I'd continued to let the engine idle, I would have landed with a cylinder and piston that resembled the one in the picture I posted earlier. As it was, I glided (glid?) all the way to Venice, FL and next day was overjoyed to discover I had a broken valve spring and not a broken valve.

Turned out I had two broken valve springs although the second one had broken so close to the end of the spring that it still functioned. I bought some dune buggy valve springs and a cheapo valve spring compressor. Buttoning it up it ran fine although it was clear from my two failed springs that the other ones were running on borrowed time. Steve Bennett had used RIMCO to to-do the heads on this engine and RIMCO had re-used the springs and other components, including the valves I'm sure. RIMCO had the reputation of being a top shop but what I learned from this experience is that you can't count on anybody else's work except your own, no matter what their reputation is. My reassembled engine got me safely home to KSEE and I started the project of learning how to do a top overhaul. I knew nothing about the job but thanks to Langford's tutorial and help from my machinist friend Don Hall who let me use his bead blaster and Sioux valve grinder, the job came out just fine. I've been back and forth across the country several times with this engine and trust it completely. Somewhere along the way I learned that Manley valves were the best so I drove up to L.A. to buy them. I ordered genuine German valve springs from Germany. New retainers and locks of course and I even matched the springs side to side as Langford describes (a bit of overkill I suppose but I was learning as I went and did everything slowly and carefully and enjoyed every minute of it). I also "indexed" the spark plugs so that when tightened to correct torque, the electrodes are positioned in such a way that the outside electrode doesn't shield the spark from the center of the combustion area. That's a bit of finessing that most engine builders wouldn't bother with but I was learning and wanted to do everything "perfectly".

That small cheapo valve spring compressor included in the pictures is no good except for emergencies. The by-far best one is the larger one in the picture - makes the work much easier.

 

proppastie

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NJ
My question has nothing to do with the valve so no it doesn't matter. I'm asking another question as I'm starting to build a VW engine. I see a fried piston there, it's a question. Does every thread you read stay on track?
of course not...however in context the question seemed to me it related to the piston that had been beat to death. Might want to start a new thread "Questions Regarding Building a VW Engine"... I promise not to say much because I never built or overhauled a VW.
 

Marc W

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Mar 31, 2017
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386
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Colorado
You all inspired me to dig out and scan some photos that I got with my CX4 when I bought it. It is a short course in how to destroy a brand new VW engine.

First you run it in the driveway. Don't worry about cooling the thing.
1584919993655.png

Until it does this.
1584920060562.png

They don't always go through the piston.
1584920132894.png

Sometimes they come through the head.
1584920203452.png

1584920249973.png

1584920285950.png
 

Pops

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The 1965, 1200 cc, 40 hp I am overhauling at this time had the same thing on the exhaust on #2 and also bent the rod. Piston ,cylinder, rod and head junk. Did you check the rod, they are easy to bend sideways.
 

Mike Stewart

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Oct 11, 2010
Messages
67
Location
San Diego, CA
What nice planes the Thatchers are! I first saw one in 2006 at Sun & Fun. Mr. Thatcher was kind of off by himself in the display area with his prototype and since no one else was around I had a leisurely chat with him. S&F 2006 was the introductory year for the Thatcher if I'm not mistaken so it had not had time to become known. I recall empathazing with this gentleman who had designed and built what seemed like a real step ahead for that category of aircraft (two-place, VW powered). He seemed very gracious and unassuming for someone who had created something so nice and I treasure my memory of that meeting.

Since then I've compared performance between the Thatchers and the KR's and - just going by published figures on the Thatcher since I don't know any one who has one - it seemed the KR does significantly better than the Thatcher on the same engine - but then the cockpit in a Thatcher is surely more commodious than the KR. For those who plan on flying two-up this particular advantage of the Thatcher is of immense importance.

Marc, I hope you've got a new engine in that nice airplane and have put some time on it. If you have, can you publish some real-world performance figures for it?

Thanks,
Mike
 

Marc W

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Joined
Mar 31, 2017
Messages
386
Location
Colorado
Opps the part about the cooling and no prop?
Yes, in these cases, usually heat causes the valve stem to stick in the guide. Then the piston hits the valve and breaks the head off. Usually it is the exhaust valve since they run hotter. This one is a bit unusual because it is the intake valve. It could have been caused by something else.

Did you check the rod, they are easy to bend sideways.
The engine was repaired when I bought the airplane. I doubt if the rod was checked but I did have the jugs off last year and wear patterns looked normal.

Mike, I have the single seat version and it does perform well. I did raise the canopy to gain some headroom. The two seat CX5 is more spacious and seems to be a real two seat airplane even with two 300 pounders in the seats. The new side by side CX7 is about to begin testing. It will be interesting to see how well it does.

My home airport is at 5,200' and I normally see average climb rates of better than 600 FPM to 10,000' even in warm weather. I normally fly between 8000' to 12,500' altitudes. I have had it to 13,500' but I can clear the surrounding terrain flying at 12,000' to 12,500'. It will true out at 135 to 140 MPH at 8,000'. I usually putt around the local area at 100 to 110 MPH. It burns under 2.5 gal. per hour when I am just loafing around locally.
 
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