Does anyone know the differences between the model 250
and the super 250?
What parts are not interchangeable?
What is the maximum length bar these saws can use?
The 250 is 80 cc and the super is 87 cc .
Both will pull a 32" pretty easy although a 24" would most likely work better .
A little trick is to change them from .404 to 3/8" .Many had rim drive sprocket systems .
The 87 cc engines in my opinion were the best of the reed valve engines that Mac had .One variation of that engine is the MC 10 kart engine ,one of the most winning engines of early karting .
I have two of the 87 cc engines .One on a 650 gear drive which has surprised more than one person who had the idea that all geardrives are slow as a snail .
Another ,a super 44A has a removable cylinder head and is closely related to the kart engine . Made in 1959 it too is surprisingly fast for its age .
These things are fun to operate for a short while but not something a person would enjoy for days on end .
AL: Have you ever seen the two cylinder Mac they made in the early 50's and if so do you now any of the specs on it? A friend of mine told me about them years ago, he had one on trial and said it was the fastest cutting saw he ever had and that Mac discontinued it becauce it was so fast cutting and accident prone.
You may be refering to the model BP-1 which stands for balanced piston . I've seen one but it didn't run .
The cause of most of them that are non operational is more often related to the carb that was used .That thing has more check valves and passages in it than Carter has little pills plus parts are all but non exsistant .
The deal was it was actually supercharged by using a seperate scavenging cylinder with a governer mechanism and were limited to around 14,000 rpm which of course was fast for the time . The engine was relatively small though and was a gear drive configuration on the saw .
The fear factor was the possibility of the governer mechanism sticking and causing the engine to fly apart like a dollar watch although I'm not so sure it ever happened .Most were recalled my McCulloch and the survivers are one of the most sought after chainsaws in the world .
another difference between 250 and super 250 is the carburetor: both of them usually has a tillotson hl series but in some case the super has a mcculloch84050 while the 250 can have the mcculloch58856C.
anyway they were quiete good saws for the beginning of the '60ies, probably non perfecly balanced comparing with other machines of the same period.
consider besides that the difference on the carburetor there is also in the second series of theese models, realized around the 1970 (the first series was introduced in 1961-62-63 more or less)
Well most of the early 250's did have Tilley model HL's ,darn good old carb .
Then out of the clear blue the designers at Mac had a dumbazz attack and put a Walbro MAC flatback carb on them . They should have been hung at high noon for that trick . >:(
Now 35 years later anyone so unfortunate to be blessed with a flat back is trying to find an HL to replace it . I imagine to only way to punish the idiots that put the Walbro flattys on is to dig them up and grind their bones .
Not exactly relevant to the topic, but heres a good find
http://burlington.craigslist.org/grd/1551489441.html
nice old mac. If I had the extra $$$ for old saws, I would go pick this one up
Quote from: Al_Smith on January 13, 2010, 06:30:52 AM
Now 35 years later anyone so unfortunate to be blessed with a flat back is trying to find an HL to replace it . I imagine to only way to punish the idiots that put the Walbro flattys on is to dig them up and grind their bones .
Exactly Al... My 640 had a flatty in it and I have an HL for it now that I rebuilt. Still need to put it in. My 797 originally had a flatty in it, but had an HL installed in it, and the linkage is a little cobbled up. The way I got it... so I need to tweak it a little.
Gary
The flat backs run okay I guess but what a pain in the behind because most have no choke ,just a primer .
Even if you can find the rebuild kits for the carbs they go for 50 bucks a pop . Most of the time the saw sold for less .
There are some Flatbacks that used a choke, my Super 250 has a choke, and yes, primers were installed on most. There are two types of primer failures, the O rings where the primer attaches to the carb (repairable), and internal wear (not repairable). I was lucky enough to find a box of NOS primers, I lost two of those to modern CA "gasoline", they melted inside.
Al is correct about the 87cc McCullochs, some of the best chainsaws ever built.
Hey Randy... good to read ya mang! ;D
Gary
Can you still get parts for the super 250? Like piston and rings, bars, filters, etc?
You might get lucky to find some new old stock parts but they would be rare .Occasionaly some filters show up on flea bay .The piston size on a 250 and a super are the same size ,just the stroke is different .I'm almost certain all the 80 and 87 cc reed valvers used the same piston and rod assembley .
For that matter often you can land a complete doner saw for parts cheaper than buying the individual parts .Like flea bay .Often the shipping will cost more than the saw on some of them .Some people go bonkers over them but they are neither rare nor highly sought after .
On that flea bay stuff I did a quick scan last night .As usual some are priced rather inexpensively and some they think they are made of gold .Typical I might add of any flea bay stuff .
Now this I will add about a reed valve Mac with a cast iron cylinder .About the only way to wear one out is to straight gas it or let it sit for 30 years on a barn floor and freeze up .They built them tough as well as heavy .
Thanks Al.
I see one on my local craigslist. It is a super 250 with 24 inch bar. The person added a video of them starting it up and showing that it runs. They want 200 bucks. I would like to put a longer bar on it. you mentioned it will pull a 32 inch bar. Where do you suggest i look for a bar?
To me it's not worth 200 bucks but that's not my call .
Bar,any reed valve McCulloch bar will fit .If nothing else a wide heel Stihl 066 style will work if adapted with bushings to take the slot from 12 mm to 3/8" the size of the bar studs on a Mac reed valver .It will take some work to align the oil hole and the bar tightener hole with a die grinder .
The longer McCulloch large mount bars are getting hard to find and even if they want a kings ransome for them .Stihl mount size are much more plentiful and less expensive .Fact being I once had a 32" GB Stihl mount size on a 250 which is why I know it will pull that much bar .That bar now resides part time on a souped up Stihl 038 Mag .
BTW in case you thought about it ,a 10 series Mac bar will not work because the heel of the bar is too narrow .Not enough room width wise to get the oil hole and bar tightening hole in .
:D More ramblings on old Macs .
I was rather unknowledgeable about what the things were worth then I discovered flea bay shortly after my first computer .Some of the old Macs I payed too much for but the same time really wasn't certain of what I was buying .So the tale of three saws two rather rare .
Mac 250,650 ,Super 44A .The 250 came with a pristene McCulloch open roller nose 24" looked nearly new .The super 44A had a 32" hard nose .The 650 came as a pile of parts no bar .
So it went like this .The 650 got the 32" and a new 1/2" chipper chain .The Super 44A got the 24" roller nose with a new Stihl .404 chisel that up this very day I've never refiled .The 250 got a very rare brand new 18" Oregon .050 groove hard nose I found on flea bay on the cheap which very conviently takes a 72 driver loop of chain exactly the same as Stihl and Husqvarna 20" loops .
So what I'm saying with all these mumblings is you can find the bars but you'll have to search them out .
I might add though which most in time find out .While the larger McCulloch reed engines have a lot of pulling power other than large wood you'll find it's much more enjoyable to use a more modern saw .Occasionlly running fine but it's not something most would care to do all time .