I've been running my Ultra Stick Lite with a McCulloch 32cc, when I first started flying the plane I was working out engine and program issues and the plane took a bit of a beating and broke both the 18-8 APC props I had (first a wide, second a standard), after that I put a cheapo prop I just had sitting around that I believe to be a dynathrust as it's black composit with square ends, it's only marked as an 18-8 not brand. I have a Master Airscrew classic also but know it's not much of an improvement over the dynathrust. I went to try to find a APC 18-8W and the LHS only has 18-8 and 18-6W, I grabbed the 18-6W, do you think this will be an ok combo? I think the Mac was turning around 7500 with an 18-8.

My Mac's, one turns 7400 with the 18 X 8 and the other was worked on by TKG and it turns 7600 with the 18 X 8 Dynathrust. They both have 12.7mm carbs and CH ignition.

Getting back to the subject. Mac's do not seem to respond so well to high rpm mods.

I think the 18 X 6W will do fine.

I have both a 18 X 6W and a 18 X 8W but have not had them on the MAC's yet.

I had almost unlimited vertical when I had the APC's on before, now it isn't so unlimited... I didn't think going down to a 6" pitch would do too much, probably around 8000rpm which sounds safe on the beefy Mac engine, I'm probably going flying tomorrow so we'll see

We have a bunch of modified Mac's here 7800 on an MA Classic 18x8. Their all starting to run good after 10 years of breakin
Had one on a tuned pipe turning 8600 no problems other than a poor throttle response (like a on/off switch)

didn't make it out today, got a new cheap commuter car instead to save about $100 a month in fuel cost... at that rate it'll only take about 4 months to pay for itself... more money for other projects

Hi Fred! I am using the APC 18X6W on my 32 MAC I opened the exaust timing to 155 and getting 8000 - 8100 rpms unliomited vertical on my Nitroplanes 71" YAK 54

For the record and for others reading this, the MAC 28/32 and particularly with electronic ignition, looks like it was designed to be a model engine from the beginning. There was no cutting needed on the crankcase. The fan shroud was bolted on. It makes a nice looking model engine. These have not been made in 12 years but there were a lot of them around. The muffler is held on by a spring/bracket assembly on the whackers. The blower version had a bolt on muffler. The spring set up is more trouble free.

I forgot to mention that I have mine set up with electronic CDI

yep, here's the mac 32 on the USL:


after pulling out the baffles in the muffler the spring didn't hold as well and the exhaust leaking out at the port made a mess, so I had to make a couple little aluminum spacers to tighten the front that doesn't have a spring

after I worked all the bugs out of the engine everyone is pretty impressed at the field, does pretty well for what it is.

My fins are not rounded and my ignition is the old original style CH but in the aluminum box from around 1999. I have welded aluminum mufflers that CH had at one time. I also have the original steel mufflers with dual outlets added in a box in the barn somewhere? I did them in the late 90's

The MAC's look like they were supposed to be a model airplane engine all along don't they..

yeah, I rounded the fins myself just because I could...

It is a shame they moved to factory to Mexico and then went out of business... I still have a couple laying around to convert.

I have a half dozen old ones in the barn that I use for spar parts for the ones I still use as whackers

yeah, I grab them up when I find them for cheap, I found a blower 32cc but it ended up being scored beyond repair... I have a couple 28cc engines in good shape though

haven't ran that prop yet, was going to go flying this weekend, but the only days it's raining are saturday and sunday... was nice all dang week but rains the only days I can do anything.

If you ever have the chance grab all the blowers you can. The big deal is that the muffler BOLTS on the cylinder on a blower and doesn't use the stupid spring.

I do, that's how I managed upon that scored engine... was all excited then found it was trashed...

I have a couple here, but I have never pulled them apart yet. Is there enough "meat" on the exhaust flange to drill and tap mounting holes??

AV8TOR

This is hard to explain but its simple once you figure it out.
Drill a 5/16 hole down through the fins from the top to bottom. One hole on each side of the exhaust port. Take a 5/16 rod and drill n tap it through the side 8/32.
Slide the rod in until the taped hole is lined up on the exhaust and then use a long bolt to screw the muffler on.
Your making a T bolt arrangement.

I have a couple of these kits from TKG and they were nice, but eventually decided to just use the springs. I made my own straps to use the springs with the welded up aluminum mufflers

Yeah, that would work. (Well, obviously it has...)

Other than looking kinda funky, is there any problem with the spring retention? They don't tend to fall off do they?

AV8TOR

I converted mine 10 years ago and they haven't given any trouble yet but the engines have been setting on the back of the bench for 5 yrs.

Well not fall off, but a BAD landing can break off the smaller of the cast spring brackets.
TKG

I removed the inner baffle on mine which made the muffler thinner and thus leak at the port (spring is only in the rear), I ran it that way for a little over a gallon until I got tired of the mess, then cut some scrap aluminum sheet pieces and bent them to go under the wire in the front. There's a notch in the muffler that keeps the spring in place, it can be wobbly and partially fall out of the port and still stay in place...

went to a flying even on saturday (got 4th out of 5 but had the biggest plane in an event where you basically have to land twice along the runway). I really like this plane, just wish it wasn't 40* at the time . The engine gave me a couple inconsistencies while running mainly when tossing it around a bit an mainly inverted, haven't checked my fuel line in a couple months. The engine is finally breaing in an runs better every time, keeps wanting to be leaned out a little.

this thing just sips fuel (12oz tank, uses half tank in a 15 minute heavy throttle flight), hand starts good, short takeoffs, and flies predictably. Just need to get a few more fancy features into my radio program but as is I'm just going to fly it...

I have a 28 out of a roadrunner wacker. It has a divider in the exhaust port like the older Ryobi.

Has anyone removed this divider or is it even worth while to remove it?