Joseph W Santora
ArboristSite Operative
For those that go that route, how many degrees do you advance the timing?
Joe
Joe
How much ignition advance?
- Thread starter Joseph W Santora
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I would not go more than 3 or 4 degrees. Saws start pulling back and become harder to pull over with to much.
Jasent
ELR junkie
All depends on the saw and what you want from it. 3-6 degrees is typical but is this a fun saw or a work saw? Does it need to start easy or does it matter? Is it a fixed time saw or advancing? What fuel do you run?
Joseph W Santora
ArboristSite Operative
I'm putting together a 353 with a 346 P/C. I noticed that if I elongate the mounting holes on the coil I can get 2.5deg of advance without having to touch the keyway. I'm installing a Wiseco popup and the cylinder doesn't have a comp release. And I only run cans of Husky fuel with 10ml of oil added to give me around 32/1.
That sounds like it should work good for you.
BrettS
ArboristSite Operative
Good to know elongating the holes work, I have a 350 I am fixing to fit a 346 p/c one day.
Shave the key no more than .020
GoBigRed
ArboristSite Operative
Heck, by using your method you can experiment. It’s no different than moving the distributor on an old hotrod. She will tell you when you go too far. Just make sure to stop and pull it back once she does. I’ve got 2-3 degrees of advance on my 10-10s that I’ve ported and it does help quite a bit. You’ll find the sweet spot
Piotr Pakuła
ArboristSite Guru
once in the old bmw I accelerated the ignition too much on the working engine, it worked great, but it did not start after turning off ;-)
calamari
ArboristSite Operative
Advancing the timing in a car engine can lead to detonation depending on the octane of the fuel you use. If you increase timing you need to up the octane. It also makes the engine run hotter. Both detonation and excessive engine heat are difficult to recognize in a single cylinder air cooled engine other than it seizes or as noted is hard to start. Be cautious with messing with the advance on a saw. No horsepower increase comes without some longevity, "driveability" issues especially when you have to guess at the amount of advance you're adding. I've never heard of a timing light being used or turning it over by hand and watching for the spark plug to fire. How do you know you've increased the advance 2 degrees? You'd have to make a degree wheel and then some assumptions that you can't verify.
Using a timing wheel you can know exactly how much timing you have added.
Jasent
ELR junkie
Ya pretty simple to measure advance
calamari
ArboristSite Operative
Let me say that the only experience with a chainsaw's timing is on a Homelite 330 that I took apart because I thought the coil had gone bad. That said, I didn't see any timing marks anywhere on the magneto and it looked like timing was handled by how close the coil was to the magnets and if the coil was "angled" slightly at the end that reaches the magnet first moving the point where the gap fires the magneto farther in advance if it is angled closer, and retarded if it is angled away. When you don't have an ignition indicator point do you just set an arbitrary point and move the coil "X" number of degrees on a degree wheel closer to where the magnets approach the coil's edge? Sounds like a pretty inaccurate way if that's it and impossible to check. If not, how's is it done simply?
You put a timing wheel on the crank. Then you put a dial indicator down through the spark plug hole and rotate it by hand until you find TDC. Then put a mark on the fly wheel and on the crank case. Also there is a needle out to the timing wheel pointing at the degree increments. By doing that you know exactly where TDC is and when you move anything you will be able to see it on the timing wheel.
Timing is done by moving the flywheel CW or CCW not by the gap to the coil. So if you move the coil CW or CCW you also change the timing.
Timing is done by moving the flywheel CW or CCW not by the gap to the coil. So if you move the coil CW or CCW you also change the timing.
calamari
ArboristSite Operative
I appreciate your reply and explanation but I still don't get it. This is the opening to a rabbit hole that the OP didn't ask for so I apologize in advance.
As you describe it, and my besotted mind comprehends it, you are assuming that the spark is firing at top dead center or...? If you don't have a way to tell when the spark is firing I can't see how you know how much or when the timing is affected. Once you find TDC all you've found is TDC. You don't know when the plug is firing or how much advance it has. If you move the pointer from TDC 2 degrees you have no way of knowing if you've moved the point the spark fires because you can't see the plug fire with the engine apart. If you move it 2 degrees and grind on the key or elongate the coil's bolt holes you don't know how much you've advanced it w/o the plug firing a strobe of some sort.
I'm willing to accept that I just don't get it but it doesn't seem to work as intended.
Smitty Smithsonite
ArboristSite Operative
Spark usually fires near or at the end of the magnet on the flywheel. The magnet charges the windings, then the collapsing magnetic field induces spark.
Have you never used a timing light. I live at fairly high altitude so I plan on at least a few degrees advanced. If you have TDC then take a degree wheel and scribe five and ten degrees which is pretty much all you need. Go too far and you should feel a rattle or vibration. Back off and it should smooth right out. Thanks
I am not explaining to you when the spark actually happens. I was just explaining how to tell how many degrees you moved the flywheel. That way you would know how much advance or retard in the timing you did.
Like smitty mentioned you would have to have a way of measuring the spark itself to know where it is in relation to TDC. But I do not need to know that in order to advance the timing by 3 or 4 degrees.
When a saw is cranking at 13,000 rpm's the spark starts to occur later after TDC then it does when at 2500 rpm's.
Like Ted Jenkins said a timing light will show the spark.
Like smitty mentioned you would have to have a way of measuring the spark itself to know where it is in relation to TDC. But I do not need to know that in order to advance the timing by 3 or 4 degrees.
When a saw is cranking at 13,000 rpm's the spark starts to occur later after TDC then it does when at 2500 rpm's.
Like Ted Jenkins said a timing light will show the spark.
Joseph W Santora
ArboristSite Operative
I get what calamari is saying. If I'm correct, people don't advance the timing from 2deg btdc to 4deg btdc. They just advance the timing 2 deg. I don't know if there's an accurate way to tell what the timing actually is. But you can accurately measure how much you advance it....I think.
I didn't use a degree wheel. I scribed a line on the flywheel, moved the coil, and scribed another line. I then measured the distance between the lines and used the math thing to see what angle it subtended. So I would not know what the exact timing would be but I know I can move it 2.5 deg.
You got it. like Ted mentioned in his post a timing light would show the timing.I get what calamari is saying. If I'm correct, people don't advance the timing from 2deg btdc to 4deg btdc. They just advance the timing 2 deg. I don't know if there's an accurate way to tell what the timing actually is. But you can accurately measure how much you advance it....I think.
