I bought a used Mcculloch Power Mac 330 with a broken bar mount stud from the neighbor for 20$ a couple of months ago. It ran good so I thought I would tear it down to see if it could be used for R/C airplane use. What I found was a front mounted carb/ rear exhaust, needle bearing equipped engine that seems to be in good shape internally. It did not look very useable to me, so I reassembled it back to wood cutting status.

Would this 33cc mcculoch engine be worth converting, or should just I leave it in the saw and forget about it?

Ron

I have a Mac 10 from the early 70's Which I think is 32cc that was almost unused that someone gave to me. You've just about described it in your post. I put a 14" roller tip bar on it and use it as a saw. I couldn't see any use for it as a airplane engine. The Mac 3214 14" (current production) saw that I have, has the Carb and exhaust correct but still the needle bearings. They both seem to have more gusto than a stock 32cc Mac Weedie. I've sorta thought about putting the 3214 chainsaw jug and carb on a 32cc weedie crankcase? The weedie crankcase strips down to look like a model airplane crankcase and it has ball bearings and a cantilevered crank. But the timing is rather mild.

Enjoy,

Jim

Thanks, w8ye for the reply.

I guess I'll just leave the saw as is, it would be quite challenging to convert to airplane use. I could strip it for parts, carb etc. or just save it for yard duty.

Ron

Hi rsjr! My friend has a 340 model of that chain saw which fits your description perfectly but his is a 35 cc, we converted to airplane usage and believe me it has a lotta power try to convert it you will like the results, if I can get a hold of a digital camera I will post some pictures so you can see how the conversion was done, right now we are waiting for the bearings that we ordered because the engine had some play on the ones it came with, but believe me it has POWER. In case you decide not to convert it let me know if you will sell it I would buy it from you if you want to get rid of it?

aero nut,

A while back I converted a well used 38cc mucculloch for airplane use. During bench testing with a 20x10 wood prop it would run for a few minutes, then slowly die, like it was overheating? It had quite a bit of end-play, so maybe that was the problem.

I was afraid I would run into the same problem with the Power Mac 330 (32cc?) so I thought I would ask some questions. I will tear it down again this evening and post some pictures, just to be sure we are talking about the same engine.

I've become kinda partial to the homelite saws, so I may just sell this mcculloch to recoup my 20$.

Ron

Here's a pic. of the old Mcculloch 38cc.

Ron

I disassembled the Power Mac 330, it's much easier the second time around. I forgot that this saw is "solid state ignition" equipped. The crank has no end-play and is actually tighter than my like new 33cc homelite. I wish the carb was located in a different location...

Hmmm... I wonder If I could modify this flywheel/ignition system to work on my ryobi or homelite 33cc conversions ?....


Heres a couple of pic's, tell me what you think!

Ron

yeahp thats exactly the same one my friend brought me and believe me it runs real nice, as soon as I get ahold of a digital camera I will send you some snapshots of the conversion, by the way the location of the carb works very well where it is once you make the prop hub you will have enough space in between the prop and the carb, we cut off the rear crankshaft extension and eliminated the oil pump case and sealed the hole with JB weld, as soon as we get the bearings we will mounted on a RYANS REBEL and tach it to se how many RPM'S we are getting on it.

Here are the photos that I promised

here are some more photos

Thanks for the pic's, aero nut.

That's a cool looking conversion, the motor mount is ingenious. With the carb mounted directly behind the prop I wonder if you get some sort of "Ram Air" effect?

That would be great if you could post some numbers on your Mac powered Ryans Rebel when you get her going.

Ron

Does anyone know if they make a 20cc or so version of this engine? I'm trying to find one like this (front carb, rear exhaust) to put in a GP Tiger Moth. The cowl is narrow and I didn't want to cut it up.

Hey rsjr! are you still thinking on selling that engine, if so let me know how much you want for it and how much it would cost to be shipped?

bdtsr! the only engine that I can think of in the 26 cc size would be a yard machines string trimmer (ryobi) it has a rear carb and exaust ifm its to l;ong you could modify the firewall of the tiger moth to accomodate the length of the engine I saw one at home depot but it was to small for my needs

I looked at the Ryobi's and I think they will be too heavy. I may see if I can snag an Echo (16cc or so) somewhere and modify the case so I can rotate the cylinder 90 deg. Of course I may have to re-pin the rings.

aero nut,

if you want the Mcculloch, just pay for the shipping costs and you can have it. I don't know what it would cost to ship 5# or so from Montana to Mexico but it could'nt be that much. If you are happy with it, send me a couple of Mexican coins for my collection and we'll call it even.

Ron

Hi

Aeronut
I saw the motor mount with aluminium of your Power MAC
A friend of mine have a Mac engine but it is 32 or 33 cc and we are playing with diferent mount system but the mount crack because it is not enough sturdy.
Your mount is cool !
The Mac have two rings, have points and the owner manual say use oil at 16 to 1 ratio, the engine was overhauled , new piston and rings ,new oil seals and have very good compresion and start by hand, 50 / 50 , the other half times put a rope over the prop adapter and start easily.
We need a plane for it. And we have a second Mac ready to go, not started yet.
Do not tached or thrust measurement but it is promising.
Many thanks for your invention
Have fun
Jose

Thanks rsjr!!!! I am realy greatful for your generosity what else can we rcr's can spect, you can bet that engine is going to be used properly I will send you some mexican smackaroos for your collection (have some old ones somewhere) and some pick's once I have convert it and mounted on a special design I am working on; my shipping address is here in the U.S. so I will get in touch with you via e-mail for all the details

Sounds good aero nut, good luck with the Mac and happy flying!!

Ron

that engine is a 2.1 cu. in. (34.4 cc)
just looked it up
got one myself was going to use a homie 25cc but this thing looks like it will be better suited to my purpose than the homie

I just picked up some of those mac motors
having a look in side its good to see proper tansfer ports
was worried about the lack of thrust support but figured it out and its easy
there is room on the crank to put a needle style thrust washer as well as shims.
they will only run on the bottom half of the case but this is fine
You will be able to shim the engine so its right
its a cheap and great solution and will last forever.

the good thing about this engine for is how thin it is
of course it gets wider with the exhaust on the back
but the front mounted carb looks great and with a velocity stack on it will look awesome

ok am trying to load some pics to explain what i mean but i cant