Crazy Legs

I test flew my re-built, cleaned up H60F Goldhead engine today in my Ultra-Stick 60 airplane. I bought this engine on e-Bay recently, disassembled it, cleaned it all up, and installed new bearings. So the piston and sleeve were in fact brand new as the seller stated in the sale, it's just that the bearings had rust on them and the top and bottom of the cylinder had a layer of rock hard oil coated on them. After I broke the engine in on a Test Stand the engine runs fine and idles fine on the ground, but on all six final approaches today, the engine quit when I reduced the throttle on Final Approach. It didn't quit right away; it waited till the pane was straightened out right in line with the runway. FYI, I'm using the recommended 5% Nitro fuel OS recommended for this engine and a new #7 Glow Plug. I have adjusted the bleeder air adjustment to there is a nice transition from idle to full throttle and the engine doesn't quit when holding the fuselage straight up. This is very strange, but a consistent repeatable problem. My Brother thinks I should switch to a newer, better carburetor that has a low speed idle mixture and use 10% or 15% Nitro fuel, but the instructions specifically say to use 5%. I'm going to include a photo of the type of carburetor that came with this engine.

the Wasp

My Feedback: (1)

I have seen engines do as you describe (stall just before landing). in these cases it was because they simply had too small of a prop on them, meaning the engines were not loaded correctly. what prop do you have on it?
if you have a 10 inch or smaller prop on it you should really have an 11x7, 8 or 12x5, 6 inch prop on it. the larger/longer prop will create more "Flywheel Effect".
the OS 60/61 size engines love the APC 12x6, but those engines don't respond to throttle inputs with that prop as well as they do with the APC 11x8. I say they love the 12x6 because they run vary-vary smooth with it.

although, your problem could also be because your fuel tank it too low. or your old and worn carb has an air leak when hot. did you use all new O-rings.

Jim

Crazy Legs

I'm using a 12-6 wooden propeller with the engine installed in the Ultra-Stick 60. The Carburetor has been sealed to the crankcase with Silicone RTV to ensure of no leaks (see above photo). Here's the long and complete story so you all will know what transpired: I had two of these H60F Gold Head engines. The oldest one I got in 1973 as a gift, and it needed to be disassembled because it hadn't been used (turned over) for 20 years or more and it was all bound up with solidified oil and fuel. So I disassembled it and put it through the hot anti-freeze in the crock-pot deal. It came out looking brand new! The 2nd engine I got from a guy on eBay for $110.00 about two years ago, but, this guy just let that engine sit around in his garage for 40 something years without lubricating it up any more, so the bearings in that 2nd engine got pitted and so the crank shaft didn't turn smoothly. I bought new bearings from Boaca Bearings and installed them in the front of that newer front crank case section and also completely cleaned up that newer engine. Here's where I may have messed up, but I don't see how it would make a difference: I took the front crankcase from my old engine which still had good bearings and installed it on the front of the newer H60F I got off of eBay. However, when I went to put the newer carburetor from the same newer engine onto the front Crankcase section of the older engine I couldn't get the two black screws to line up with the carburetor with the gasket installed. So....I took the gasket off (to lower the carburetor threads a little) and I used Silicone II Sealer instead, which should be even better than the gasket. However, I thought I should state that that's what I did in case that may be attributing to the stalling during final approach. Also, the reason why I swapped the front crankcases is because I was anxious to see if the new engine I got off of eBay would run decently, and it did. FYI, I never replaced engine bearings before, so I had to research that and order the bearings, which took a lot of time. So while that took place I put the newer engine together with the old crankcase front part and ran it on a test stand. The engine ran beautiful on the test stand with an 11-7 prop. When I installed it on my Ultra-Stick I changed the prop to a new 12-6 because my Chicken Stick ruined the leading edges of the soft 11-7 Beach Wood Master Airscrew propeller. I think my next troubleshooting step will be to install the original, older carburetor (which has a low speed adjustment) back on the older forward crank case using the Black OS Plastic Gasket. That way I'll be eliminating the possibility that the newer carburetor isn't designed to be used with the older crank case. Also, the newer OS H60F I got from eBay had a cheaper carburetor model that had no low speed adjustment.

tedsander

Setting air bleed carbs can be frustrating. Hence why everyone moved to ones with low speed needles.
You may have good transition, but it may still not be right. Do the "pinch test"
With it running on the bench, at idle, pinch closed the fuel line to the carb.
If it dies quickly, you are too lean.
If it runs for a bit and then dies, your are in the sweet spot. (it may gain a few rpm at the very end, but not much or for long).
If it runs, and picks up rpm significantly before dyeing, then you are too rich.

If it passes those tests, then I would look to the RTV as you thought. Some versions are rather poor for resisting some alcohols. But one would normally expect a poor idle due to a leak to rear it's head in several situations, and not just the one you noted.

larry@coyotenet

My Feedback: (21)

Try riching the idle airbleed a little. The engine is probably leaning out some as it runs and when you idle down it is a little too lean. Check to make sure the center line of
the tank is even with the fuel intake on the carb, if it is low it will lean out as it empties, Gold heads were great engines, I flew one in the mid 70's and still have two set aside. Mine always liked 11X7 props.
Larry

1QwkSport2.5r

This guy was advised on another forum what to do. He’s not using the right glow plug, it’s not set rich enough, and he isnt listening to the sound advice he’s already been given.

partshunt

Greetings, can anyone advise from their best experience which glow plug is best for idle. The engine is an old K&B 61 with an original glow plug have an idle bar. I cant find any such glow plugs any longer. The best modern glow plug for good idle is what I need for spares... OS #8 is one suggestion.... others? Thanks in advance.

the Wasp

My Feedback: (1)

can't find Idle Bar Plugs! how about buying them from K&B
K&B and FOX GLOW PLUGS (mecoa.com)

Jim

the Wasp

My Feedback: (1)

oops, see my post above^

Jim

partshunt

Thank you for the suggestion. I have ordered K&B engine parts to rebuild my ole 61 from MECOA and missed out ordering the plugs. However, thinking I could buy modern low idle plugs if they work good, save time and shipping by buying local. Back to the question, what type of glo plug is best for idle on a 61? Doesnt matter if they have an idle bar or not. Main thing, what are the successful plugs, I have been told OS #8???

the Wasp

My Feedback: (1)

OK I see. try an OS #7 or #6, both are hotter than the OS #8 and Enya #3.
the OS #6 is the Hottest. it was re-named, it was called A3, very hot.
the OS #7 has only been around like 14? 15 years? it was born when the #6 was re-named.

Jim

os_glow-plug-chart.png (740×710) (liveracemedia.com)