Chainsaw Repair

What is the bar mount on a mcculloch 740 ?

Yep.  Large frame Mac mount.  Cannon code for it was MC.  Dunno what the Oregon code for them was.  I have several Oregon made bars for those saws (many originally sold as Mac bars), but they don't have mount code on them (as Oregon wasn't putting the three digit codes on bars at that time).  They have the xxxxxxx Oregon part #'s, which are meaningless to someone who doesn't have old Oregon catalogs...

The large frame Mac mount is similar to the old large frame Homelite F014, but not the same.  Sometimes they can be interchanged (usually with a little bit of modification).  Would really like to know what the Oregon, Windsor, GB, and General codes for the large frame Mac mount were...

The 740 I put in the FS area sold quick. Local right behind me.  But this 36" rollernose was left.

Just as general info of what I've said before it's very easy to adapt a Stihl mid size bar to a large mount Mcculloch .

The reason I say Stihl is about everybody makes them .Big old Mac mount are not so easy to find in decent shape .One of my 125 wears a 36" 066 size mount and does very well with it .

A UXL mound Windsor bar (for a XL series Homelite, such as a SXL-925 or 750) will work on a large frame Mac if the right bar plates are used too.  That bar mount approximates the 'slim line' bars that Mac was selling for the later large frame Macs.  Those 'slim line' Mac bars looked like an enlarged 10-series mount, with oblong adjuster holes that also fed oil to the chain groove.  The UXL mount bars have oil channels from the adjuster holes to the groove (in addition to the separate holes for use on the Homelites).  A D096/D196 mount Oregon bar (also for Homelite XL-series) will also work here IF they have the right oil channels.  Older Oregons do, while the newer ones sometimes don't.  That can be remedied with a little work with a dremel/foredom if need be.

The profile of those bars (and the UXL) is narrower than the original LF Mac mount, and can cause interference between the chain and the bar plates (and clutch cover and bar pad).  Mac's solution was a special set of bar plates that don't have the usual flared edges, and are about twice as thick as 'normal' bar plates.  They were to be used in combination with the later style LF Mac bar plates (which also look like enlarged 10-series Mac bar plates).

I did up a couple of detailed posts regarding the different LF Mac bar mounts and plates (with pics and info about what combinations work and what doesn't) on AS a couple years back.  I oughta cut/paste it here.  Been meaning to, but haven't gotten around to it yet......