Mobile dimension sawmill motor

[aspo]

Hi, I picked up a Mobile dimension mill at an auction, with a seized motor. I ripped the motor apart and unfortunately the magnesium block has the white cancer and is not worth rebuilding. I have access to vw cases in good shape and could rebuild a motor with one. I noticed the MD case was cut on one end which would be easy to replicate. I could use my old case as a template. Was there anything internally with the case modified by MD that anyone knows of? The crank is longer but was there machining done to accomidate this? My saw was built in 1980 and the case is stamped 1700 (assuming 1700cc). I have attached some photos of mine. Thanks for reading this and I appreciate any responses.

 

 

 

 

[DennisK]

That case doesn't look too bad, careful of the cleaner you used, it'll turn the case black. Is the crank pitted? Do the bear have even wear?

[longtime lurker]

I vaguely remember reading somewhere that the MD engine was somewhat modified from a standard VW motor, but I can't remember any details as to what the difference was. Contact Mobile Manufacturing, I'm sure they can answer your questions.

I ran a 127 for a test cut once. I didn't buy it - I was seriously underwhelmed by the performance. It may have been a weak engine or something else like a pulley size changed at some point: but it was a slow cutter, about half the speed I expected based on my experience with similar types of saw. If you don't know what the saw is supposed to be able to do it's hard to judge, but maybe a repower with something else is something to consider

[aspo]

That case doesn't look too bad, careful of the cleaner you used, it'll turn the case black. Is the crank pitted? Do the bear have even wear?

Crank is good thankfully.
Tough to see in the photos but the bottom of the case is eaten away pretty good near and around the oil pan from sitting for 15 years. 

[StorminN]

I vaguely remember reading somewhere that the MD engine was somewhat modified from a standard VW motor, but I can't remember any details as to what the difference was. Contact Mobile Manufacturing, I'm sure they can answer your questions.

I ran a 127 for a test cut once. I didn't buy it - I was seriously underwhelmed by the performance. It may have been a weak engine or something else like a pulley size changed at some point: but it was a slow cutter, about half the speed I expected based on my experience with similar types of saw. If you don't know what the saw is supposed to be able to do it's hard to judge, but maybe a repower with something else is something to consider

An old 127 will max out at about 43 feet per minute carriage speed in the cutting direction (twice that on the return trip).

The carriage drive system on the belt drive 127's is pretty fickle on adjustment. If the main engine belts aren't tensioned correctly – the two that provide power for the carriage drive will slip and not move the carriage fast enough. Same thing with the primary feed belt and the Vari-Drive belt... they all need to be adjusted just right, and readjusted as they stretch. The only belt that should slip is the final drive belt, it's a V belt but it's run on just the inside flat of the belt, used as a "fuse" so if something jams, this final drive belt will slip and prevent parts from breaking.

I've owned an old 127 for about 20 years, and if I don't run it for a while and come back to it, I can forget how fast it's supposed to be cutting. When the VW is running correctly (good gas, clean carb, good points (I have since upgraded to electronic ignition)) and making maybe 45hp on a good day, my 50-year-old mill will cut and edge 1x8's at about 43 fpm... here's a sample.

Mobile Dimension milling 1x8 cedar at 43 fpm - YouTube

-N.