KR> dropped valve
On 8/4/2015 8:35 AM, Earl Klinker via KRnet wrote: > Mark, > > The #3 cylinder was then the hottest running cylinder. The VW distributor had a 2 degree offset so the timing was later than the other cylinders to keep it cooler, Virg > > ___ > Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search. > To UNsubscribe from KRnet, send a message to KRnet-leave at list.krnet.org > please see other KRnet info at http://www.krnet.org/info.html > see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to > change options >
KR> dropped valve
The discussion on VW valves has been great. I am glad both of you were left unscathed. I tend to agree that we do not need the large valve heads for our application, the larger seats leaving less metal between the exhaust and intake valves. I developed a leaky exhaust valve about four weeks ago and when I removed the heads to recut the valve seats, I found a small crack between the valve seats on one cylinder. These were the heads that came with the engine from TOC originally purchased 1999 by the builder. I had around 110 hours on the heads. I always have had good temps on both heads and ran a little on the rich side for EGT. I could not tell there was a leaky valve operating the engine, but could hear it when I pulled the prop through by hand. (A habit I have always practiced with WV aircraft engines after shutdown.) I still had the heads from my old KR that I had purchased many years ago from CB Performance. They are the 044 heads that have the thicker combustion chambers and the large stainless steel valves. When I received the heads originally, I installed them without doing anything to them. I had around 300 hours them at the time of the crash. When I removed them the valves had some wear in the seat area and the guilds were really egg shaped, but the heads were still sealing well and still had good compression. The guild wear I attributed to poor valve train geometry. I rebuilt the old 044 heads with new one piece stainless valves, new guilds and recut the valve seats with Neway cutters and am now using them on my present KR. I"m thinking of purchasing a set of stock heads with the smaller valves, but stock heads seem to only come in the 1/2 inch combustion chamber thickness. All of the 3/4 inch thick heads have the larger valves. So right now I'm not sure which way is the best way to go. Does someone know if you can get something like the 044 heads with stock valves? Seems like that would be the best of both worlds, or does it even matter. Maybe I should just fly the plane and stop analyzing. Roger Bulla -Original Message- From: Virgil N.Salisbury via KRnet Sent: Tuesday, August 04, 2015 1:59 PM To: KRnet Cc: Virgil N.Salisbury Subject: Re: KR> dropped valve On 8/4/2015 8:35 AM, Earl Klinker via KRnet wrote: > Mark, > > The #3 cylinder was then the hottest running cylinder. The VW distributor had a 2 degree offset so the timing was later than the other cylinders to keep it cooler, Virg > > ___ > Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search. > To UNsubscribe from KRnet, send a message to KRnet-leave at list.krnet.org > please see other KRnet info at http://www.krnet.org/info.html > see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change > options > ___ Search the KRnet Archives at http://tugantek.com/archmailv2-kr/search. To UNsubscribe from KRnet, send a message to KRnet-leave at list.krnet.org please see other KRnet info at http://www.krnet.org/info.html see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options
KR> dropped valve
Should have given full history: first heads with a factory built HAPI 1835 cc engine, valve guides were too tight, had to ream them. Messed up the plug threads; reamed them out and installed 14 mm inserts. Did this on the following heads too: rebuilt heads from a quality VW supplier: big mistake, lasted less that 100 hours. Final heads from one of the best serving the VW crowd. All heads bored for 92 mm jugs. Swivel foot lifters from the get go, .006 on intakes and .008 on exhaust, 25 hour oil changes and valve lash adjustments. Read the mixture conditions from the plug colors and exhaust piped (4 individual pipes) plus egts and head temps. Compu-Fire on 009 centrifugal distributor, plus an old Whitney distributor advance/retard unit to fine tune advance; and mixture control carb. Two rebuilds with new cranks and hubs after prop breaks over the years on the HAPI 1835 cc engine. at 1080 hours removed the HAPI engine and built up a GP 2180 cc engine, new case to RIMCO for front welding and super hub machining. Last valve job July ?07 at 1315 hours. Think I did a reasonable job of maintaining the beast. Wish I had the Bug Pack aluminum crank case in the KR2 that?s in my 1970 bus, 69 x 90.5. The case is set up for long throw crank and 92 mm jugs. Have over 40,000 miles on it and a lot of mountain driving here in eastern Oregon (the southern Blue Mountains) with oil changes and valve lash check one a year need it or not. Oil pressures are as new.
KR> dropped valve
Earl said, > "The bus engine blew up in Minneapolis" Keeping VW bus engines running turned many a now-old hippy into VW mechanics. Old School Yearbook Pics View Class Yearbooks Online Free. Search by School & Year. Look Now! http://thirdpartyoffers.juno.com/TGL3141/55c0f86a878c7786a26bbst01vuc
KR> dropped valve
Mark, You and others bring about some very good points. I do agree that one of the biggest issue with the car engine is that the cylinders were cooled via a fan that was on the back of the generator. This then forced air through an oil cooler, after which, that same air was to cool the cylinders and head. The #3 cylinder was then the hottest running cylinder. On my bus, I did have an external oil cooler and also had an air scoop on the side of the to force more air into the engine compartment and the oil cooler was mounted so the outside air crossed it first. The bus engine blew up in Minneapolis. In retrospect, I believe one of my biggest issues was getting the valves adjusted to the precise clearances. The other was my young age and trying to drive the VW harder than was meant to be driven. Now I am an old person that knows better. I have also been very educated from you and others about the valves themselves and did not know the information about how the original valves were produced. Thanks much for the education. Earl
KR> dropped valve
Dave Feiger wrote: >> If I do a rebuild I will use the Manley SS exhaust valves; shied away in the past thinking that they would be softer and more apt to burn??? << There are some cheap 304 stainless valves out there that will mushroom quickly on the tips if you don't use swivel feet, but if you buy Manleys you won't have that problem (although I wouldn't run a VW engine without swivel feet). I've been running Manleys in my 2110cc '74 Karmann Ghia since 1978, and that engine now has well over 200,000 miles on it. This is based on 35 year-old information though, so some research as to exact material strength is probably still in order (disclaimer). and Earl Klinker wrote: >> Was this the #3 exhaust valve? In my case it was number two. The deal with number three only applies to cars because the oil cooler obstructs the cooling air to the number three cylinder, which is not applicable to most aircraft engine installations. Having said that, temperature balance depends on the cylinder baffling. Number one and three would run hotter than number 2 and 4 without some baffling to prevent it, so there is some truth to that, because they are at the rear and are fed air that's already been warmed by 2 and 4 out front otherwise. Balancing out the temps is something done during early flight testing, but does require four CHT probes. CHT probes under the spark plugs will read a LOT higher than probes under the head studs, but it's apparently debatable as to which one you should go by. I choose to go by my standard on the Corvair (and the probe location that spark plug CHT probes are designed for), under the plug. If you want to feel good about your CHT temps, the head studs are a great place to put them! And with only one CHT probe, you're pretty much clueless as to balance. As for Microbuses, I worked at Prestige Motor Cars in Las Vegas (the VW dealership in town) for two years around 1980, and during the summer the VW busses would be lined up at the gate on Monday morning...victims of the heat, climbing the mountain from California, and then coasting down the NV side pulling a high vacuum. That produced a lot of sucked valves. I should have known better and replaced those valves (whoever made them) with the forged stainless valves I had on the workbench. That one's on me, and if nothing else, should be a warning for others... Mark Langford ML at N56ML.com http://www.n56ml.com
KR> dropped valve
I will have to check my maintenance book but probably had about 300 hours on the engine since doing last valve job. Installed new TRW exhaust valves when ever I pulled the heads. If I do a rebuild I will use the Manley SS exhaust valves; shied away in the past thinking that they would be softer and more apt to burn??? Yes it was cylinder #3. I used modified VW Type 1 cooling tin with air inlets from the front of the cowl, always kept head temps under control: less than 300 degrees F, sensors under the rearmost upper head bolts on each side. Oil temps were a problem with this arrangement. Solution was an additional 5 by 11 plate style oil ducted cooler under the engine; full flow through an oil filter into the oil cooler then into the front oil galley. Oil temps running 180-190 in cruise, never over 200 F.
KR> dropped valve seat ~ ~ ~ ~ Damned good handling of an emergency!
Too much knowledge is like a car too fast or too much money . . . . . . . . The more ya know, the further you'll go!
