Squire

20+ year old Webra 61 - Runs (at least for a few minutes), overheats, and quits.

Used VERY little - maybe 6 tanks at most and that was years ago. Front bearing replaced. Running Cool Power 15%, OS A3 plug. No cowl - all open. 12x6 prop. Perry Carb. Slimline Pitts style muffler.

No, I'm not trying to sell it! I can't figure out why it runs so hot. I thought at first it was due to being cowled in. Removed cowl - same results. The high speed carb adjustment VERY wide - trying to run it rich but the adjustment has little effect. It will lean out to the point where it quits but I can adjust it very rich with little rpm change. Pinch test indicates that it can be leaned out more.

All fuel lines checked and appear okay. Pressure line to muffler seems okay. Tried 11x7 prop - overheats faster and quits sooner!

All bolts are tight - head, front and rear, plug. No foaming in fuel lines.

I'm at a loss now and need help - please.

Phil

jay2000dakota

Phil that is one hell of a weird problem, Is the engine clean? dirt and dust between the cooling fins could cause the overheating. Is the fuel tank mounted correctly (fuel outlet on the centerline of the plane) that could cause the mixture problem. You migh try rebuilding the carb, the only other thing i can think of if rebuilding the whole engine (bearings,ring,gaskets and complete carb rebuild). Im all for keeping old engines alive but you might just be better off to buy a new one, for the simple reason that your not dealing with these head aches.

sledge_78

My Feedback: (24)

Phil,

Usually when these engines run hot, they are running too lean or too much Nitro. Since it is an older engine I would try 5% or 10% nitro fuel with Caster oil content around 20%. Also, look for an air leak around the carburetor base or the carburetor itself. I am not a great fan of Perry Carbs so I would pobably look for a Webra TNII carb to replace the Perry. I have not had much luck with the Perry carb. Make sure the Perry Carb you are using is made to fit this engine, If you know the Perry model number you can check their web page to see if it is the correct one. Try some of the above to solve our problem one will work.

Gerry

da Rock

Ringed engine?

Older engines required far more breakin than ones today. They also weren't as accurately made as today. They also evolved using castor oil based fuel. We often had to run them an hour or a couple of hours to break get them reliable enough to fly. I'm not really sure it that engine is old enough to have all those characteristics, but I'd bet on it having some. The metal in older engines took awhile to break in. You had to basically wear the tolerances down where they were too close. And there were more of those places. And the metal was meant to last, not wear down fast.

Needle valve adjustment being very wide would be expected if the needle threads are very fine, or the needle taper very fine. If not, then the engine is having a draw problem. Are you running muffler pressure? Tank close to the engine? All the usual questions about tanks, plumbing........

huck1199

Try adding 4oz of castor oil to a gallon of your fuel. I use Klotz Benol Racing Castor. Double check for air leaks as suggested above.

jaka

Hi!
Too much nitro!!!

Gray Beard

My Feedback: (-1)

Just A thought, when the front bearing was replaced was the rear shield on the bearing removed??? Should have been or the engine will run very hot very fast. I'm going back A long way down momory lane but wasn't that engine designed for FAI fuel??

Squire

Thanks Gray Beard. Since I wasn't the one to replace the bearing I don't know if the shield was removed or not, but I can probably find out.

As for FAI fuel I really don't know. I had a friend (now deceased) who had the same engine with the next serial number and feel quite certain he didn't use FAI fuel.

This is a strange engine. We got it to run over 5 minutes wide open without the cowl and tied to the ground - since then I haven't been able to get more than 3-4 minutes and it gets VERY hot. I'm still using the same fuel - 15% nitro. This may be a bit too much for this old engine but it sure puts out a lot of power. I don't have any tamer fuel nor do I have any castor oil.

I'm going to pull it out of the plane (see avatar) and put it on a test stand to eliminate any plumbing problems or foaming problems.

Several have suggested that the fuel could be the problem - lack of cooling oil content. I'm wondering if that bearing is siezing. Your's was the first to suggest this as a possible source. I hate to trash this engine and fork over $$$ for a modern one - like an OS.

Thanks again.
Phil

Villa

If the engine is able to draw air from other places then it will lean out and run hot. Seal the rear cover; replace the O-ring that seals the carburator to the crankcase; replace all of the other O-rings on both valves. Make sure there are no screws missing from anywhere. Use automotive silicon sealant on the muffler-to-crankcase flange and on the muffler halfs. Use Loctite on the screws holding the carburator in place to secure them AND seal them.

Squire

Problem solved! Thank you guys for all your input.

I took it to our local engine guru who ran some of "his" fuel through it without any sign of overheating. - 320ΒΊ. His blend is 10% nitro and 20% oil including some castor. Engine turns 12,200 rpm with a 12x6 prop.

With my Cool Power 15% nitro and unknown oil % NO castor it almost immediately went up to over 420ΒΊ! Problem solved!

I bought a jug of fuel at LHS 5% nitro and 20% oil including castor. I haven't run this yet but expect much the same as the guru's fuel. He said to mix it half and half to get the nitro up to 10% and get the castor in the mix. I'll try that too as I have an almost full jug of the 15% stuff.

Thanks again for your input.
Phil