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Engine basics => Engine set up tips => Topic started by: Motorman on December 12, 2016, 03:21:08 PM
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I've got allot of K&B 4011 stuff left over from my racing days. I read on stuka that they are a good stunt engine with mods so, might be a fun project to put on a Brodak Lagg 3 Lavochkin 8).
I've got the early version light weight front case and the later crank case with the exhaust lugs. It was real wet nosed so I got a double sealed front bearing and left both seals on. I ran it and it sealed so good even the grease stayed in.
They say to lower the sleeve and modify the porting and head but no specs. I can take a good guess and probably come out ok but, anyone know exactly what to do?
Thanks,
MM
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Parrently was a article in PAMPA , Stan Powell / Les Mc Donald one .
The ' P ' ( stamped 0 head is the FAI Pylon One, straight Fuel / No Nitro . Blew about 8 plugs with mine.
a Gasket may be the answer . LL~ Chambers same as 21/40 ST , squish band & bowel ( same Dimns. )
Sucks a bit of juice, but not top bad . sleeve Timings 140/120 odd stock .
Power comes off n on , down & up , even with a perry pump backplate , for rough air fuel feed . S?P
Theres a few other threads here on them , but nothing definative - untill someone posts the Stan Powell Article HERE . PLEASE . ;D
(http://stunthanger.com/smf/index.php?action=dlattach;topic=7936.0;attach=24036;image)
He won the World Champs with it , once or twice. So it cant be complettely useless . S?P
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I run the engine with good results. The "P" inscribed heads (on front) are from the pattern version of the K&B 40. The P head has a hemispherical combustion chamber. They can be found on original K&B 40 R/C pattern engines, or with luck, in the spare parts bin. Details on my successful K&B 4011 engine (converted from R/C) are:
-The P Hemi head.
-Retrofit 0.280 venturi with a K&B or ST NVA.
-Extra head gasket (0.010").
-APC 10.5x4.5 prop.
-Fuel 5 to 10% nitro with 20-25% oil (50/50 syn/castor)
-Tongue muffler adapted to engine.
Engine will run in a "wet 2-cycle style" real nicely with a slight increase in RPM in the right places. The APC prop really works well on this engine - recommended! One caution from my experience... The crankshaft on the small front end 4011 version tends to be delicate. A hit to the ground can bend the crankshaft itself (not just the prop bolt stud). So word to the wise, don't crash!
Cheers
DZ
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Thanks for the specs, I'll check my head for letters. I have to find or make a light weight muffler. What are the size and number of holes in your tongue muffler?
Thanks,
MM
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I will need to check on the number/size of the tongue muffler holes. It may take a couple days.
The tongue muffler wasn't anything special. Just local made by a machinist/modeller, and supposedly for the Double Star 54. The tongue muffler just happened to also fit my K&B 40. A convenient match, so I bought the muffler for the K&B. I ran it as purchased. If you have access to either of the mufflers supplied with the old DS 54 (there were two of them I understand - a tongue and a tube style), then you could have a ready-made piece with no work on your part.
Check all this out before committing major $, of course. I am going from memory on the mufflers for the old DS 54. I could be wrong on the recollection. I just know that my local purchase tongue muffler runs fine on the K&B 40. There was no special magic with it.
The key factors with this engine, in my opinion, are the P Head and the APC 10.5x4.5 prop. The APC prop really allowed the K&B to give an acceptable run for me. Other sizes/brands did not perform as well, at least the ones I tried. The APC 10.5x4.5 prop seems to also have a very good reputation among my friends for many .35 to .40 motors, and has worked for me. That's my $0.02. Hope it helps as a start point. Experiment to see what works best for you.
Cheers
DZ