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O540 Parallel valve vs angle valve, which is the better?

I know some people that run straight valve Lycomings on pump gas and they do great. They have plenty of power & run cool all day long.

I don't have any first hand experience with the angle valve O-540, but I do run the same piston/compression in my angle valve 170 (4 cyl.). If I run mine real hard for an extended length of time it will start losing power and missing. Back off & give it a second to cool off and it runs fine again. The oil temp is never hot when this happens, so I think it builds up heat in the cylinders. I've always been curious if this was a problem created by the angle valve jugs having a little more compression.
 
Parallel have lower compression and in theory produce less heat.

Angle Valve produces alittle more Hp (290 angle carb versus 250-260 parallel carb).

Lots of more parts around for the parallel narrow deck than the angle valve narrow deck in my opinion and they usually are cheaper.

Which is better I don't know. There are some guys around here running 0-540s and the best airboat lycoming mechanic around here says he likes the parallel better over the long haul, said it has less problems.

Then there are those guys with parallel cylinders with the angle valve pistons or helicopter pistons in them to get more compression. (I can dig up the parts numbers). So what appears to be sitting on the engine stand can be misleading.

I run a angle valve 0-540 on a 13 riveted palm beach hull and have held the foot in the carb for at least 25 minutes straight running marsh (2600+ RPM steady). Watch that temperature gauge on the oil like a hawk and used to have a cylinder head temp on #3 cylinder. When they start creeping I just throttle her back to 1500 and turn into the wind, but seldom have a problem. Running 100LL straight and changing oil every 30 hours. It will run 2200 to 2400 all day long until the fuel tank is empty and has never missed a lick. At this time I am looking for a parallel to rebuild as a spare, just due to cheaper parts and availability.

Know a few guys running unleaded in their parallel 0-540 as well and they don't say anything about problems.

Only complaint is during cold weather (like below 30), thick oil and metal shrinkage makes you need a good battery or starting is a problem. But that occurs only every few years around here. LOL

Cracker - So I say it is a toss up or just don't know enough to point out the difference.
 
I run a angle 0540 My oil gage starts at 100 and I never see it go any higher that that. The trouble is if I stop and shut down after 5 minutes I can't restart until another 20 minutes. Does anyone know how to correct this?? Timing?? A fuel?? I would like to run pump gas $$$ not A fuel. Other than this I realy like the 0540 angle. I've had 4 and other 6's but this is great.
 
Here is an in depth discussion of your problem:

http://www.sacskyranch.com/eng16.htm

Does it turn over as fast when hot? What kind of mags are you running and do they have some sort of start ignition besides the impulse couplings? Are there impulse couplings on both mags?

I don't have any experience with Lycomings in an airboat, that why I visit this site, to learn. I have flown airplanes with them. There are minimum oil temps for these engines which are probably around 140 to 150 for proper lubricaion with the 50 weight oil. I have seen other statements about airboat installations running cold oil temps. I don't understand why this is happening. I know there are oilcoolers with thermostats.

Jim
 
After about 10 min after shuting down, it will not turn over very good. I think it take about that much time to build up heat in the jugs.
Well the rest of you question I'm not shure of, I'll have to check what type mags when I go to Ozello to run. I never thought of haveing two impulse mags. Will visit the link also. If you can think of any think else I would realy appreciate it.
Thanks Phil
 
I have read that the problem can be the starter heat soaking and not being very efficient. There is a procedure in the above web site to check the voltage at the starter while cranking to see if it a connection problem, and the remedy. Cleaning all of the connections and a new starter might fix it. If the connections get corroded and drops the voltage it can overheat the starter and damage it so it will turn slow even if the connections are fixed.

Here is the link:

http://www.sacskyranch.com/voltage.htm

If the thing turns slow the impulse does not work well. My son has an O540 in his airplane that has 11 to 1 compression and fuel injection. He uses Slick mags with "Slick start" in one. There is no impulse at all. The Slck start supplies primary voltage from the battery and the slick electronics to a seperate set of points which is retarded spark only for start. After it starts it switches back to the regular points with normal spark advance. It solved his hot start problem. I think the Bendix similiar system is called "Shower of Sparks".

Jim
 
I have been running two impulse mags for a while. If the impulse mag. goes down in the field, I am not interested in hand propping a 0-540. So if the spring in one breaks or a condenser goes bad you still can start easily. The other problem is people getting confused which mag is the impulse magneto and sit wearing a starter out trying to get the #@&%# thing to fire up. (yep that was me on a buddies boat after he rewired the control panel and crossed the p-lead wires.)

I changed out the standard aircraft starter for a high torque starter. The starter is a high torque, high rpm starter (I think for a toyota), it fits a coarse tooth flywheel gear, spins the motor faster than a standard lycoming starter at about 1/3 the weight, and is cheaper to rebuild. You can get the cheap one at CarQuest, and probably Autozone, I have the part number for one of those places if anyone is interested.

Just be careful if you are running with your timing advance a couple degrees to get more power. You can get alittle more power and RPMs, but you get more heat as well. If you get a kickback, the cheap starter's mounts are very likely to break. :wink: Trust me on that

You can get the conversion plate at most airboat companies in Florida and I know Mark's carries them. He also carries a high torque starter with a much stronger mounting bracket. With those two changes I have not had problems with that palm beach hull or neither have any of the other 2 lycomings are running around with. Just something to think about.

The angle valve 0-540 temperature on the palm beach hull I run sits at about 120-130 at cruise (1700 to 2000 RPMs) and gets up around 160-180 if we are running in the 2400 - 2600 RPMs. I have seen shrouds on 0-540 on airboats to get the temperature up to recommended aircraft operating temperatures.

There is a good Yahoo Lycoming discussion group for airplanes that all sort of topics appear. Mahlon Russell with one of the major aircraft overhaul shops fields the questions. I think he was a mechanic with Lycoming for years and is now in charge of customer service or something at Mattituck Aviation I believe. Here is the site.

lycoming@yahoogroups.com
 
Phil - you might want to check that temperature gauge. Both I and the guys I run with have had lots of problems with Temperature gauges giving false readings or not functioning. I have one on my tool shed shelf with less than 5 hours on it and it does not work.

A quick check is buy a candy thermometer for about $10.00, grab a old coffee cup, fill with water and microwave it. Put in the candy thermometer and the oil temperature gauge in the water and see how they compare. If you run a test from just slightly hot to touch water to steaming water and check it each time, you will have a good idea if the oil temperature gauge works.

We have had several oil temperature gauges that work great from 100 degrees to about 140 degrees then the two start splitting.

Just something to think about.

Another idea is a spark plug type mount for cylinder head temperatures. The neat thing with one of these is you can change it easily in the field from cylinder to cylinder to get an idea of which cylinder is the hottest. By monitoring that cylinder, you know exactly when to throttle back due to overheating. You can set this up for less than $100.00 and sure will save 250 to 350 dollar cylinders. I used to have one set up, but the gauge and lead broke. I hope to get another made up before next summer and hot weather running.

Over heating of cylinder heads can cause extensive cracking around the plugs and various other problems.
 
Thanks for all the info. I have though of getting a high torque starter. I put one on my hot rod and it will start anytime I hit the key. The starter is next to the headers. I will check all of this stuff out after hunting season.
Again thanks Phil
 
Phil,

I have just suffered through the exact problem you describe - on a parallel valve 0-540 on a 13'6" Gilileo. Drove me crazy, again.

Swapped to a 100 amp CCA start battery, no luck. Changed all battery leads & found a hidden problem waiting on Murphy. But, no real chamge on my Dodge truck starter.

Junior Jurnigan of Plant City diagnosed the problem in about 15 seconds. He installed a high torque Mitsuninzo (sp?) starter and mounts from Air-Tech (800-366-4746). Cured it. Spins like a gyro now.
 
I thought a high torque starter would restart my engine. I haven't even look at my boat yet but I would realy like to know why the TEMP never get to 100 on my gauge. I will check the gauge.
What TEMP do most of you get on your boats?
 
Phil - The angle valve I am running was hanging around 130-150. Gauge is dead right now. I know an Airgator with a parallel valve that sits at 120, unless you are dogging it. It still sits around 140 at the highest.

Know two 540s that ran normal aircraft temperatures on airboats. One ran about 180 for about a year, and then they realized that the pistons were shot. Don't know if the bad pistons and the temperature were related. Had a buddy running a parallel valve on a Panther in Cal. a few years back. He had a shroud built around the top of his engine deck. The A&P mechanic who rebuilt and installed the motor built it to cause temperature to increase into normal aircraft ranges. However, the boat started running on the hot end during the summer and they couldn't figure out what was up. Replaced the cage, stand, and engine for a 350 and reduction gear to get more power. Another airboater got the engine and I got the shroud. The motor is still running I think, at more normal temperatures without the shroud. I have never used the shroud, but still have it.

Remember that most of those aircrafts have shrouds and ducts that cool the engine off. If some of those vents get stuck overheating is common.
 
Beware of the cheaper brand of high torque starters. One kickback and the mount brackets are shot. They don't warranty the mounts LOL. Going on another trip to starter shops looking for another bracket (second time).

Go with Big Daddy's information at Jurnigan or call Mark's, both have heavier duty starter mounts available to place on these High Torque starters. Both Mark and a buddy warned me of about the cheaper ones.
 
If your motor is freshly rebuilt and the mechanic used pistons
with less then .007 piston to cylinder clearance thats your
problem. pistons expand as they get hot.
Ya get what ya pay for qualified air-craft engine rebuilders
know. and backyard shadetree mechanics learn on your buck.
if a angle valve cylinder has a valve that sticks its like
having a bomb go off inside the motor total catastrofic destruction.
straight valve engine will survive a stuck valve and keep running.
 
Can he sv 540s run ground as good as the av’s? Looking to purchase the a/v, but people seem to say they are pretty much the same. I’m asking because on an outboard, 30hp is a noticeable difference through the whole spectrum.
 
Phil said:
I run a angle 0540 My oil gage starts at 100 and I never see it go any higher that that. The trouble is if I stop and shut down after 5 minutes I can't restart until another 20 minutes. Does anyone know how to correct this?? Timing?? A fuel?? I would like to run pump gas $$$ not A fuel. Other than this I realy like the 0540 angle. I've had 4 and other 6's but this is great.


does it crank?

My does it to some degree, because the motors hot. More hp to crank it over. Now my motor just need to turn over doesn't need to crank fast one to two turns and it will start but it is slower turn when hot. To change my motor to pump gas would require changing compression.
My 540 angle valve originbaly only has 7.3:1 that could run on pump gas but now i run 10:1 compression thats straight av gas. I use to run car motors but with this 540 I never want to back to a car motor.
 
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