Author Topic: Old Canadiens ignition timing warning  (Read 431 times)

0 Members and 28 Guests are viewing this topic.

Offline trappermike

  • 5 cube
  • ***
  • Posts: 129
  • Karma: 17
  • 40 years mechanical and 2-Stroke racing experience
  • Location: British Columbia, Canada

  • Total Badges: 17
    Badges: (View All)
    100 Posts Level 4 50 Posts Third year Anniversary Second year Anniversary Level 3
Old Canadiens ignition timing warning
« on: December 29, 2018, 01:39:11 pm »
I have an old Chainsaw Repair Manual that covers many old saws,including the 275/276 and 3980/390. I noticed in the tune-up section for these saws that ignition timing was supposed to be set at 35 degrees,this is far more ignition advance than I've ever seen on any 2-stroke,and any 2-stroke that is advanced too far the piston can overheat and seize. I think I finally figured out the answer- those saws were run at 16-1 gas-oil mix using #40 motor oil,an incredibly "Thick" fuel/oil mix,with that much oil in the fuel the burning rate would be slowed down a lot,making a lot of extra ignition advance needed.
Here's the catch-if you leave the timing as original and now burn a 50-1 mix with modern 2-stroke oil,this is going to burn far faster than the original 16-1 sludge,making the timing too advanced for modern faster burning fuel mixes,possibly overheating or seizing the piston.To counter this I would suggest retarding the timing to about 30 degrees and/or using only the best Premium fuel. The ignition advance on most modern 2-strokes is often between 24-28 degrees.
I just don't want to see someone restore and get running one of these old models(with no spare pistons available) only to have the piston fatally seize,that would be a shame!
Experience builds real horsepower...
When the hammer drops the BS stops:Loggers sports competition!

Share on Facebook Share on Twitter

Like Like x 1 View List

Offline Al Smith

  • Moderator
  • Nitro Hotsaw
  • *******
  • Posts: 2779
  • Karma: 181

  • Total Badges: 34
    Badges: (View All)
    Tenth year Anniversary Nineth year Anniversary Eighth year Anniversary Level 6 Seventh year Anniversary Sixth year Anniversary
Re: Old Canadiens ignition timing warning
« Reply #1 on: January 01, 2019, 09:37:01 am »
Many older saws used more advance

 

Related Topics

  Subject / Started by Replies Last post
8 Replies
1252 Views
Last post May 12, 2012, 09:30:03 pm
by Al Smith
11 Replies
1738 Views
Last post August 11, 2018, 12:02:54 pm
by Cut4fun .
4 Replies
891 Views
Last post August 02, 2012, 04:06:14 pm
by splitpost
timing

Started by jmester « 1 2 3 » Stihl

20 Replies
1872 Views
Last post January 17, 2013, 09:06:02 pm
by 660magnum
6 Replies
1203 Views
Last post December 18, 2017, 05:45:22 pm
by Philbert
21 Replies
6852 Views
Last post October 17, 2016, 08:19:31 pm
by dannyupsolate
0 Replies
335 Views
Last post October 12, 2016, 02:12:43 pm
by Cut4fun .
Saw timing

Started by rls8836 « 1 2 » Poulan

12 Replies
1073 Views
Last post April 06, 2017, 07:46:22 pm
by 660magnum
4 Replies
538 Views
Last post November 02, 2017, 06:30:13 am
by Al Smith
1 Replies
129 Views
Last post December 07, 2023, 10:01:51 pm
by 3000 FPS