eball

My Feedback: (37)

I just finished a conversion of a McCulloch PRO MAC 610 60cc chainsaw engine. I have been working on this engine for quite a while and just got around to finishing everything this past week. The engine is on a Kangke Texas Hurricane and should go for some test flights with the engine this weekend. I previously had a 46cc Poulan on the Hurricane, but thought it could use a little more umph for pull out. With a little tuning this morning the engine has turned a 22x8 MA scimitar prop 6900 rpm. Throttle response and transition are really good and really smooth so this ought to make a great flyer. I'll post all of my pictures in my gallery and let everyone know how the first flights go if you're interested. All up weight of the engine with mounts, muffler, prop and spinner ready to bolt on the plane was 4 lbs 14 ounces. I know this is a little different than how others weigh engines, but it's the true weight. Compared to the Poulan 46 the engine is about 14 ounces heavier (we'll see how much difference this makes in flight characteristics). The ignition is a CH with syncrospark.

davewallace

My Feedback: (29)

Hi,
Nice Job. A couple of questions. Did you turn the fins down? Is this a needle bearing engine?

Dave

diablo_r

another question, have you got any pics from above or the side...?

eball

My Feedback: (37)

Dave,
I turned the fins down using a makita grinder with a 60 grit sanding wheel. Pretty basic but it's cheap and did the job. This is a needle bearing engine (why do you ask?). I weighed the complete Texas Hurricane without fuel and my digital scale says 16lbs 5 ounces. I also hooked a strap around the scale and got a little over 22lbs static thrust so its should go vertical a little. Here's a couple of pictures of the top of the engine. Thanks

davewallace

My Feedback: (29)

Hi Eball,
I am working on two engines with roller bearing crank shafts. A Homelite 26ccXL and McCulloch 33cc Mac 130. The Mac 130 has no thrust bearing other then the end of the roller bearing cage. The Homey 26cc has brass washers on either side of the crank counter weights. I am a little concerned about the thrust bearing issue causing loss of rpm.

Dave

eball

My Feedback: (37)

Dave,
To be more specific on the bearing question: The crankshaft is supported by a large diameter roller bearing in the front and a small diamerter torrington caged needle bearing assembly in the rear. The big end of the rod uses loose needle bearings and the little end uses caged needle bearings. The large crankshaft roller bearing is pressed on and controls thrust on this engine.

eball

My Feedback: (37)

I did some flying this weekend with the new engine. The plane was previously on the tail heavy side and needed no elevator input while inverted with the poulan. The switch to the Mac 60 only required three clicks up elevator and I actually like how the plane flies better with the extra nose weight. Vertical is tremendous and pull out from a hover is excellent. I will definately have more confidence down low with this engine once I get it dialed in. I had several dead sticks and multiple problems with the new engine however (this is where it takes major persistance and drive to not get frustrated and quit while doing conversions). The first problem found was that the low speed needle kept backing out while the engine was running. I loctited the needle and it still did it. My final solution was to shorten both high and low needles to nubs (these were almost 2" long needles originally). The lesson learned there is to never run long needles in an airplane because the vibration and extra mass from the length of the needles can cause them to oscilate and back off. Once the needle problem was solved I still had a couple of dead sticks. On the final dead stick I came in very hot, landed and as the plane reached the end of the runway the landing gear came off while hitting some rocks. I took the motor off and looked everything over. The first thing I found was a massive air leak in the intake track. Apparently one of the carburetor mounting screws penetrated a gasket and caused an air leak in the fuel pump pressure channel. The second problem I found was another air leak in the rear crank seal. The seal was damaged so I decided the best thing to do was eliminate the seal since no shaft needs to protrude out the back. I gutted the original seal and soldered a penny in it to seal it up (it only cost me a penny). I also ground a little more material off the end of the crank in order to clear it from the rear of the engine. The engine is now sealed up VERY tight and without the rear seal the rotating resistance while spinning the crank is VERY low. It will be interesting to see it this makes any difference in performance. While I had the engine out I went ahead and weighed it a couple of different ways. The engine ready to mount minus muffler weighs exactly 4 lbs. Add the muffler and it weighs 4lbs 5 ounces. I feel that this is a pretty respectable weight for a 60cc engine and hope to use it in some of the 50cc size airplanes that are becoming popular. If everything goes well I'd like to first try it in the new Aerotech YAK-54 once they start shipping. I'll let everyone know how testing goes once I repair the hurricane. Hopefully my problems are solved and the engine will run consistently now.

captinjohn

Eball: Sounds like you got a nice 60cc engine in the works. How is the viabration level....compared to the poulan 46? Is the Mac 610 easy to find? Thanks Capt,n

davewallace

My Feedback: (29)

Hi Eball,
That sure is a light 60cc. It doesn't weight much more then your 46cc. You sure are right about conversions. Each engine is a prototype and needs to be debugged. The end result and feeling of accomplishment is definitly worth it. Thanks for the updates.

Dave

KenLambert

My Feedback: (107)

you can find the mac 610 in almost all pawn shops they are also montgomery ward same thing and there were a few other names for them I have forgotten. The mac 610 was the first conversion I ever did it is still sitting on my shelf . I ended up doing several of them and flew a couple .What I found out is they are a long stroke engine and will turn larger props at about the same RPM with good torqe.

eball

My Feedback: (37)

Mr. Lambert,

What props did you have the best luck with? I have a 24x8 that I can try, but I'm afraid it's going to be too much for the engine. These engines are pretty common and cheap even on ebay. I purchased two saws for somewhere around $30. One had some significant scoring on the piston, but this one was in very good shape and has so much compression you just about can't turn it over by hand (without using the prop). I've about got the airplane repairs done and I plan on flying this weekend. I'll let you know if I got all the bugs worked out.

Eric

eball

My Feedback: (37)

Captinjohn,
The engine shakes a little more than the 46, but still isn't bad at all (shaking could have been caused by air leak??). The CH syncrospark helps a lot and I'd hate to start the thing with timing fully advanced. When I was initially setting the timing and starting the engine the first few times it tried to rip my arm off a couple of times

Eric

bee2

Hi you have more photos or the conversion process, I have the same engine
Alvaro

radzilla66

Any pics? Looking to use the same engine.