Scully

Hi all,

I hope these questions are appropriate here.

All about Norvel BigMig 0.061 setup:

( I am buying two (CL and RC) and would really like to clarify some details - I read everything on the Norvel site, but still confused!)

I am a beginner so this is about general RC setup (not competition):

1) I do not need muffler pressure for BigMig to work well (as opposed to AME) - true or false - or sometimes? What most people do?

2) Will it work well with 10% nitro in reality (throttled) - I know Norvel site says it will even work with 0%, but most people say 20%+?

3) Plugs - do they come with Freedom XL plugs now? if not - what do I need to use one (a special Freedom XL glow head + FXL plug?).

4)Compression: !!!
most people recommend using 3 shims to lower compression so it lasts longer/easier to start etc... (correct?)

Which shims are these - (under plug or under glow head) and is this for the Freedom XL head+plug?
Now if they do come with Freedom XL when I buy one - do they come with 3 shims (lower compression) when I buy them or do I need to buy them separately. Most model shops do not carry them....

5) The best breaking in technic for them seems to be 'cold' breaking first with head removed and motor oil (like 10-30) and just turn it manually (100 times+). Then glow plug back on with 3 shims and usual rich / half lean cycling.
Any additional hints pls?

6)Extended Norvel tank (1oz) -
this one is like usual 1/2 built in radial tank (a-la Cox BW) but extends through firewall. Is it a good idea?

Or may be I should not bother and simply install it without Norvel radial tank and use somebody else's 1 oz tank - a good make in this case? I am buying ACE Whizard...


Thanks very much
Sergei.

Fishstyx

My Feedback: (15)

I have a couple of these engines on Lanier 1/2A shrikes. I'll try to answer the questions I can:

1) From what I can tell, yes. Our Skrikes (the club races them) have 1oz tanks about a 1/2 inch behind the engine. On occassions, the nipple on the muffler has broken off in flight. In each case, the engine immediately quit.

2) Should work fine on 10%. Our club mandated 15% nitro for our races and it works just fine. (~20k RPM with a master airscrew 5.5x4)

3) Not sure, we just use the stock plugs.

4) I use 3 shims for the first tank or two (for breakin) then go to 1 shim for max compression / power). The shims are under the glowplug which is held in place by the head. The 3 shims come with the engine, save them.

5) You got it. I use some pure castor on the piston for the manual rotation with the head off. I spin it with the starter motor instead of simply twisting it by hand.

6) don't know, we use external 1oz tanks.

Jason

Scully

Thanks Jason,
Your reply is extremely useful for me as it gives me the basic knowleage I was missing. People in most cases just forget you may not have that basics - even Norvel site....

I am a bit surprised I need muffler pressure though, I really thought Bigmig Startup/Sport runs well on suction...
Anyone uses them like this? What about stock Startup's tank Black Widow style 1/2 oz tank - is it suction or does it implement muffler pressure internally?

I understand Norvel's extended tank is very much the same as http://www.jkaerotech.com/ slickmount which is supposed to be one of the best (but Norvels is plastic...). May be someone here could explain about them - are they designed for suction od muffler pressure?

Thanks again
Sergei

Fishstyx

My Feedback: (15)

On other threads I've read about people having no problem with the engine running without muffler pressure. I would assume that in order for it to work, your fuel tank needs to be very close to centered on the carb. This isn't a problem if the tank is attached to the engine. Also, in another thread people were discussing the use of balloon tanks to provide positive fuel pressure.

Jason

MAKdaddy

My Feedback: (5)

I run Norvel AME .061's with nothing but basic muffler pressure and have no engine-run problems. My planes are more aerobatic than fast so they spin less RPM and this might be why I can get away with nothing more than a muffler tap. I would reccomend buying the r/c version even if you don't use the throttle yet (Wire it open) It's $24 for an r/c carb if you decide you want to slow down. Kinda pricey. I run round sullivan 2oz fuel tanks and always run the thing dry. I have a very stubborn idle--but not how you'd think--I often have problems shutting the engine down for a belly flop landing, it just wants to run, idle set screw is as low as it will go too. To me the integral tanks limit the airplane design and once you get used to these little engines, you'll want to stay in the air alot longer than the integral tanks allow. I get 14 minutes per tank at mostly full throttle. One head shim is the way to go after break in. I run 20% car fuel since the lubricant is close to norvel's own hard to find fuel. There are several heads availible. The freedom Xl is oem and works great, haven't replaced one yet (150+ flights), there is a conversion head to use OS #a3 plugs, but I hear it costs power. There is also a diesel head out there. Interestingly, cox glow plug's bolt right on and I hear they raise compression for more power, haven't tried it yet myself.