gcb

Anyone using the BigMig .074 for CL?

I replaced the carb with a venturi from a Big Mig .061. So far, so good. I have not yet run it. Wondering if anyone else has tried it?

I plan to build a stunt ship of around 32"-34" wingspan. Not sure if it will be profile or full fuselage at this point.

George

dennis

My Feedback: (90)

Be very careful with the first start of that motor. Follow their directions implicidly or you could have a bent rod. If you don't feel like flipping the thing over while loaded with oil and then letting it sit overnight like they say then make sure that you have warmed the cylinder before you start it.
These motors aren't used too much by the C/l crowd as it is a between size. However, it puts out quite a bit of power. Easily equal to the old baffle 15's of yesteryear.
Don't run it rich trying to break it in. start it and get it up to temperature . Keep it in a wet 2 cycle and use good fuel. In spite of anything that you might hear they really need quite a bit of oil and 25% is about right. It can be half synthetic and castor ,but do use some castor. After all if your flying it C/l and get off a tad lean you don't have a throttle to kill the motor ,so it cooks in the air.
The 074 will fly a 30 inch plane but do be reasonable with the weight.
Have fun
Dennis

gcb

Dennis,

Thank you for the reply.

My question was more aimed at how the engine handles for CL use, ie. what prop, any fuel draw problems with using the .061 venturi, etc. I plan to use a 7x3 prop and NVX-15 fuel with extra castor. Probably a uniflow tank with no pressure (at least at first).

I have a dozen or so NORVEL engines of various sizes and types but thanks for including the break-in and running information. It's nice to have a review and a second opinion.

As for the .074 size, I fly mostly for fun and will never have the top (or even bottom) PA flyers shaking in their boots, so engine size doesn't matter.

George

Andrew

Hi George --

It's nice to hear Lew's name and Lexington come up in the discussion.

Since the R/C carb had been interchangable between the .049, .061 and .074, apparently fuel draw is not a significant player. However, I have always thought that the .074 would be a little restricted with the same size throat as is used with the .049, but it may run better without pressure than the .061. I have noticed that SIG now carries a .074 carb.

At least for R/C, the 7x3 seems to work best for me.

When Wildcat was blending NORVEL's fuel, I think the oil was a synthetic/castor blend, primarily Techniplate and Benol. I have no idea what SIG is now using, but a little extra castor certainly won't hurt.

NORVEL manufactures a high performance venturi that is used with the AME .061, but it has to be run with pressure due to the more open throat. The .074 might pull enough vacuum to run with this venturi without pressure and have improved performance. Since NORVEL's site has been downgraded, you can get the venturi from SIG, part no. NVL110159

Jim Oliver

My Feedback: (1)

I am also interested in the Norvel .074 for CLPA--I have the small Pathfinder waiting for the building board w/.074 waiting for the Pathfinder to be ready.

I will be watching to learn how it is working for you.

Thanks,