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You'll want to replace that fuel line with the more modern style that Mark illustrated. My MM 6 had one of those and it didn't have a chance of sealing tight. You need the plastic tank pickup with the O Ring that takes a normal fuel line to the carb

Here's the Stens Welch plugs I used on an MDC carb out of a Mini Mac 35 a while back, they are indeed 7/16". Sorry if this doesn't help, I would never guess they'd be different! I've had to take a break from working on saws, too many other things taking up my time... But I have at least one...

Oohhh you tapped those bosses in the housing for bucking spikes.... I like it. Looks like you're addicted... These saws are so cheap and plentiful it's a tough habit to break. They are very snappy saws for their size, I'm convinced a 30cc mini Mac will outperform some 42cc saws.

The Zama is, in my opinion, a much better and more trouble-free design than the Walbro MDC. Interestingly enough... I've found a healthy MDC to be easier to tune, but that's just my personal experience. Both work well when they are in good working order. Those auto oilers are finicky...

You'll want to replace both the metering diaphragm and the fuel pump diaphragm. Perhaps also the inlet needle while you're in the carb, and also check the metering lever height.

This sounds exactly like bad carb diaphragms, it's not pumping fuel.

Have you replaced the diaphragms in the carb? That should be one of your first steps with an old saw, they get stiff and stop doing their job. Stiff carb diaphragms will not pump or meter the fuel correctly and absolutely can cause it to start on choke, run for a few moments and then stall.

A lot of good advice here... I think keeping the chain sharp and the tension adjusted correctly, along with good ethanol-free gas and good oil, keeping it in the optimal RPM range, keep the fan and cooling fins clean and clear, and keeping the carb tuned correctly are my main things.

Just be warned... fixing these little Macs becomes an addiction, you see people selling or throwing them out EVERYWHERE and before you know it you have a pile of em haha... The only people that get rid of the little Macs are the guys that aren't man enough to fix em. 😁

Yep... I was going to say this exact thing. Piece of cake.

This actually makes a lot of sense, and this saw does have a lot of hours on it, I'm going to check the throttle shaft next. Thanks!

Have you encountered the tuning issue I'm dealing with on this saw? Starts, idles and accelerates beautifully, but when I run WOT out of a cut, I get a second or two of 4 stroking and then it cleans up and gains some RPMs. It's like at WOT the mixture drifts from just right to slightly lean...

I sure appreciate all the info and wish I could buy ya a beer in return. :cheers: So get this....the current needle is made of some kind of plastic / nylon, with a brass seat. I've NEVER seen anything like it. The only reason I didn't replace was because the parts in my HL kit were so radically...

Do you think the new forked style is inherently better than the old style? Could that have something to do with my weird tuning issue?

All the diaphragms are brand new, and the kit came with a new lever, needle and seat assembly, I opted to leave the originals as they are different and looked good. I could certainly try swapping to the new parts if I can't sort my tuning issue... Where are the O rings located on the adjustment...

Pic inside the carb, you can kinda see the metering lever, and the old diaphragm.

I could try very gradually going a little more rich on the hi speed to see if I can get it to 4-stroke all the time, and see if it runs acceptabley well. I suppose what are the odds that 62 year old seals can still work adequately?

The old girl is manual oiler only, it's a very early 270.

I'm pretty good at tuning saws but this has me stumped.... yeah it starts great and will sit and idle perfectly, great throttle response and power in a cut. But when I try WOT out of the cut, I get a few seconds of 4-stroking and then it smooths out and revs slightly. If I go much richer it...

Red electrical tape where it was rubbing on the housing a little.