My question to anyone is? What type and brand of fuel that works the best with these engines. Right now, I'm using Coolpower 10%. They run great, but sometimes one or the other will quit at idle. Or close to it. there isn't any low speed adjustment. Maybea diffrent type of plug? The max on the fuel is 15% will this make a difference? Thanks

Well, more nitro sometimes helps an engine idle, but it may not make a difference.

I don't know how low you are trying to idle either. If you aren't used to small engines, keep in mind that they idle at a higher RPM.

For combat, "idle" isn't usually that big of a deal anyway, so I've never worried about getting a low idle on my engines.

Skyrocket,
In combat the biggest benefits of the Norvel engines are their light weight and ability to reach high revolutions. The BigMig uses an airbleed carburetor which is less adjustable than the twin needle used on the AME and the screw for airbleed setting works in reverse of the twin needle screw. On the air bleed adjustment you screw it "in" to decrease airflow and thereby increase fuel flow. In other words screwing it in richens the engine.

As Kirk "Montague" said we rarely use idle in combat, and that is almost exclusively for start, launch and land. The BigMig is about an ounce lighter than the AME because it does not have bearings, but runs close to the same power because of its more aggressive porting.

Fuel for a Norvel engine should be 18% oil. The very hard coating on the piston and sleeve requires a longer breakin than other engines, up to one hour, before you really see its idle and top end optimum performance. There is more information on running Norvels and setting them up on www.georgiacombat.com in the Glow Section under the Technology heading.

Best of luck.

If yours IS broken in, at least an hour of operation, and you are having low end problems and some top end ones, check the head gasket. Fact is, order some more gaskets from SIG now and have them on hand, that and the head tool. Clean the head button, install a new gasket, run it to get her warm and then torque the head just a little more and it should be good for a while. I usually swap air bleed for the twin needle carb, I don't really worry about idle and the air bleed had a less flakey carb when I bought mine, don't know if they've fixed that but I assume they have.

Are the twin needle carbs any better now Lou? Or does the idle stop screw still jam up in the throtle barrel groove?

Great engines, need a little more attention to maintenance, but man do they scream on a 9x4.

Hi Mr. Clean,
I haven't bought a new Norvel in three years so can't comment on the quality of the current carbs. I did notice that every few months changes crept into the engines back then. The crank counterweight, connecting rod, and case were changed slightly in 2003 during a two month period.

Thanks guys for the great info. At one time I swapped a head gasket on one engine , because I had a leak from the top of the motor. Found a slight mar in the head. Was able to correct it. That was when I brought the motors last year. Its a good idea to change them again. I found it strange that the carbs did not have a needle to adjust thr low end. They are air bleed, but most engines have a needle to adjust. I thought you might be able to swap carbs with a twin needle. I'll look into it. Since I'm using a pair of these, I would like a good idle. Do you guys think the Coolpower fuel is OK for these or should I switch?? Lou. you said 18% is what needed. What brand do you use?

I wouldn't wash YOUR engine parts in Cruel Power, but I know folks that swear by it. You do need the 18% oil and CP just doesn't have it. What it has is really kinda a mystery, well, I looked at a jug last week and it didn't list anything.
Wildcat, SIG, Magnum fuels list not only what kind of oil they use, but the percentages by volume of the fuel.

Clean, I checked the web site for morgan fuels. The fuel I've been using has 18%. I've had good luck with it for years. But I might try Wildcat this time. Alot of guys I know are using Wildcat.

I've been running Norvel big mig for several years on different combat planes. Threw a rod on one right through the engine housing. Sig replaced even though I admitted using MCP and flying in combat. I put new OS needles on mine. You have to shorten the barrel about 1/8 inch, but the needle seems more friendly than the stock Norvel needle. Same carb though. There is no air bleed screw--just a small hole. Make sure it's clean. Rick Fraley once told me that I could bore it out with a numbered drill if I needed mored air (leaner), but once drilled, there is no going back. I resisted and I now have one of the Norvels on a delta wing thingy called a Wild Wiz that just screams. Good idle and transistion. I am using a bladder tank. I have had excellent results with regular old Wild Cat fuel (10%) and Tower plugs. The guys above are correct that these engines improve with age. My biggest complaint is the tendency for these engines to flood and lock up. I try and keep fuel line pinched off, but still have to blow out excess fuel when starting. Cost me a number of launch on time points.

(I tried to include a couple of photos. Don't know if they came through.)

Greg

Thanks Flyinggreg for the info. I didn't think about drilling out the air bleed hole. I've been making sure that it isn't clogged. I was thinking about getting the carburetor from a AME .25. But that my last step in trying to solve my problem.

Although I've run a lot of CoolPower in ringed engines, it seems to not run great in most non-ringed types. I have used Byrons and PowerMaster with great results in Norvels, both fuels have some castor and are 18% -20% oil. If your head was leaking, it might be helpful to lap it, put a piece of 800 grit on a sheet of glass and wet sand the head button sealing surface until it has a uniform sheen. Reassemble with one stock gasket (they sometimes come with three installed but, at least up to 15% nitro, they seem to give best power on 9x4 combat prop with only one shim. I've seen factory shims from .004 to .008, if i can find one i use a single .004) and tighten the head firmly with the factory wrench. check head clamp torque often. The back plates have been known to leak- remove, wipe clean, reinstall with some gasket sealer (I use Hilomar, a non-hardening sealer for water pumps, etc, available at auto parts stores, easier to deal with than RTV). The OS 25/40 FP needle valve asm will indeed fit the Norvel BM carb and seems easier to adjust, just need to grind the unthreaded tip off. the airbleed is fixed on the BM carb, you can enlarge it with number drills, just go a little at a time, and if you go too far, you can always plug with JB Weld and start over. a few thou in diameter is a lot in added area, just go a few at a time. Every Norvel BM I have is rich in the idle/midrange so opening it up a little won't hurt, I would guess. I would avoid the AME carb, i've seen other guys get the occasional lucky one but I've had several and EVERY one siezed, the carb barrel siezes against the rotor screw due to vibration, and locks the carb up with a big ol' hairy burr on the barrel. I sent em back to Sig and they repaired them but I don't trust them and keep them in a parts box and run BM carbs on my AMEs. Maybe on lower-revving sport planes they will work fine. Because of the rich low end/midrange, the Norvel runs better with a hotter plug, I've tried some colder ones such as the Fox 8 and the low end really went down the toilet. The OS A3 and 8 seem to work well, as does the K&B 1L.