Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

I'm hoping I can get some help from this forum....or at least your opinion.  Three years ago when I was transferred to Connecticut, I purchased an old (mid 70's, model 910995) ariens snowblower that I found on craiglslist.  The purchase was alittle bit nostalgic, as it was very similar to the machine my dad had and used all while I was growing up, and worked great for him.  For the past three years, no problems....quick to start up, and threw the snow with ease (even the heavy crap we sometimes get in CT).  This fall, I changed the engine and gear oil, filled up with fresh gas, and gave the carb a couple of shots of cleaner while I let it run.  It ran for about 15 minutes with no problem and I was confident it would be another good season.  During the big snowstorm we got over Christmas, it did not go well.  The blower worked for about 10 minutes with no problems, then shut down.  No sputtering, or sounding like it was running out of gas, just died. I restarted it with no problem, and it ran another 5 minutes, then the same thing....died.  I continued to clear the driveway like this, a couple of minutes of running, then die, then restart.  Sometimes it would die when under a heavy load, other times not. 

So a couple of questions:

     -Any suggestions on what I can do to improve/fix this problem?  The way it runs fine, then shuts down without warning, then restarts easily makes me think its more spark then fuel related.  Any thoughts?  I haven't done much work on small engine other than the normal mainenance, but am reasonably mechanically inclined. 

    -Unfortunately, I have no way to bring the blower to a repair shop.  My local shop will pickup/dropoff for $75.  Add in another $100 or so minimum to repair, and I've spent close to 200, and still have a 30 year old engine.  Looking online, I can get a replacement motor that I could put in for about 250.  Doesn't this make the most sense?  I'm pretty confident I can swap out the old engine, less confident of my troubleshooting/repair abilities. 

Thanks for reading, and appreciate any advice.

trouts2 wrote:

Right -- maybe I described it wrong.  I've read the procedure in the manual, and the part of concern was finding BTDC and the use of the dial indicator.  Once you get that, your right, the rest doesn't seem bad.

   The BTDC can be gotten right as I mentined but you can use just TDC and that will work well enough.  If you want it a hair better you can guestimate  someplace between BTDC and TDC and you'll also "well enough" plus.   Friiy once said about, "It's not a funny car".  True but I don't know how much would be lost by going TDC instead of BTDC.  If anyone knows please post it.

How many degrees or mm before TDC is the recommended setting?  If you know how many mm before TDC,  you can take the head off and use a caliper to measure where TDC is then back the piston down the number of mms to achieve the correct setting.  It's not really that complicated.  Especially on an old Tecumseh flat head. 

trouts2 wrote:

I'm assuming that "BTDC" means "before top dead center".   If it is, this is the point where maximum ignition advance is set. 

In an engine with static advance, (as in an engine with points), the position where the advance is set, will be where the piston is located when the spark occurs to ignite the fuel in the combustion chamber.  A static advance setting is usually a compromise to allow for a certain range of rpm.  More advance at lower rpms will generate more torque but the same advance setting at much higher rpms will be detrimental to the engine, both power wise and mechanically.   In a relatively low revving four stroke engine, such as used in OPE, it is desirable to have maximum advance as prescribed by the manufacturer.  It will make a difference in power.   While I do most of my engine work on two cycle engines, the principles of advance are the same.

You should set the piston at recommended BTDC for maximum allowable advance.  In this case, I'd rather have a bit more advance than not enough.     

borat wrote:
Any guestimate on how much?

trouts2 wrote:
Hard to say, but I'd bet that It will be noticeable.  Particularly torque. 

With high performance two cycle engines, some guys like to flirt with maximum advance due to the additional available torque it provides at lower rpms.  The downside  is that high rpm power and reliability are compromised due to too much advance.   I equipped my modified Yamaha two stroke engines with programmable dynamic ignition timing.   Maximum advance is 24.3 degrees from 500 to 4500 rpm.  From there, as rpms rise, I set the computer to retard advance values progressively until its at 16.5 degrees at 9500 rpm.  That way, I get all the low end torque due to lots of advance and top end power and reliability by retarding it.  If I were to spin the engine that fast with 24.3 degrees of advance, the engine would detonate (pre-ignite) so bad that it would destroy itself.   

Correct advance is important.  Particularly in an OPE engine where torque is paramount. 

>>static advance, (as in an engine with points)

Does that also apply to SSI?

Interesting on the adjustable.  What's the name of the device.  If I google around I'll get all car stuff.

trouts2 wrote:
Not sure what SSI is. 

I have an Echo chainsaw with automatic ignition advance.  The acronym for that is SAIS ( Slope Advance Ignition System automatically    
adjusts ignition timing for optimum performance).  Is SSI something similar.

The units I use on my Yamahas are made by a European outfit named MZB and Zeeltronic.  There are three components:  the dynamo, the controller and the programmer.   All of the original electrical generating and ignition parts are eliminated and the new stuff replaces it.  If you just go with the dynamo and static ignition system, you end up with an analog system.  Add the digital controller and now you have programmable ignition which is programmed by plugging in the programmer and inputting the desired curves.  

Here's a couple links showing the MZB system and Zeeltronic controller:  

http://www.powerdynamo.biz/eng/systems/7106/71067main.htm

http://www.zeeltronic.com/page/vcdi-04.php
  

SSI is just an abreviation for solid state ignition, electronic ignition.

OK on the auto advance modules.  After looking at those I remembered looking at them before I think after you mentioning them in another thread some time ago.  Nice for peaking a Yamaha bike but a bit over for a snowblower. 

This brings up a constant confusion so I post a seperate thread.

Most definitely not needed on a snow blower.  Not enough rpm to be concerned about. 

However, proper advance setting is important if you want to get maximum power and torque from the engine at speeds under 4000 rpm.