Advancing ignition timing on a saw

[hrhunter]

What are the advantages of advancing timing especially on ported saws? Reasons? Theory?

 

[w8ye]

Advance the timing very much and you get the handle snatched through your fingers

 

[FATGUY]

My understanding is this. With a ported saw, you generally gain RPM. With a gain in RPM, you need to start the burn "sooner" to get maximum power. Think of it as if you were pushing someone on a swing. If you wait too long to push, you only get your finger tips on them and you don't transmit as much power.

 

[SierraMtns]

My understanding is this. With a ported saw, you generally gain RPM. With a gain in RPM, you need to start the burn "sooner" to get maximum power. Think of it as if you were pushing someone on a swing. If you wait too long to push, you only get your finger tips on them and you don't transmit as much power.

I like how you explain that. Thank you.

 

[Frank Rizzo]

Advance the timing very much and you get the handle snatched through your fingers

advance too much /poor fuel quality saw goes boom real quick !

 

[SierraMtns]

advance too much /poor fuel quality saw goes boom real quick !

This is good to know. I thought my ported 372 xp X torq sucked the fuel already and it has stock timing.

 

[Frank Rizzo]

This is good to know. I thought my ported 372 xp X torq sucked the fuel already and it has stock timing.

I was referring to detonation which is difficult to detect in a two-stroke ... the engine will literally blow itself to smithereens !

 

[Ted Jenkins]

Most engines that I have worked on start to ping or rattle when timing has gone too far. Yes big damage can occur pretty fast with timing gone awry. I have gone as much as 9 degrees advance with great results. Because of altitude. I would suspect that one to three degrees if you are under 3,000 feet would be OK. At 8,000 feet I like to kick them up at least 5 degrees. Fuel burns slower at greater altitudes, but if you are at 1,000 feet or less then do not get too aggressive. Thanks

 

[Frank Rizzo]

Most engines that I have worked on start to ping or rattle when timing has gone too far. Yes big damage can occur pretty fast with timing gone awry. I have gone as much as 9 degrees advance with great results. Because of altitude. I would suspect that one to three degrees if you are under 3,000 feet would be OK. At 8,000 feet I like to kick them up at least 5 degrees. Fuel burns slower at greater altitudes, but if you are at 1,000 feet or less then do not get too aggressive. Thanks

great point !

 

[president]

My understanding is this. With a ported saw, you generally gain RPM. With a gain in RPM, you need to start the burn "sooner" to get maximum power. Think of it as if you were pushing someone on a swing. If you wait too long to push, you only get your finger tips on them and you don't transmit as much power.

good analogy

 

[blsnelling]

Even most otherwise stock saws benefit from some additional timing advance.

 

[Frank Rizzo]

Even most otherwise stock saws benefit from some additional timing advance.

The only issue I have with that line of thinking is fuel quality ... maybe a non-issue in your area however in my locale you can literally see 1-4 mpg differences in fuel economy depending on which station you fill up at ! Several of us have tested this on 100 mi highway treks with cruise control set at 65 and observed said results ... if you happen to get low-budget fuel with a higher-compression engine and advanced timing it may be enough to cause damage !

 

[grizz55chev]

Computers do all the timing adjustments on today’s cars , and yes, better quality fuel means better fuel mileage. The real damage to modern vehicles related to fuel is the fuel system itself, fuel pumps, injectors, filters etc.

 

[Frank Rizzo]

Computers do all the timing adjustments on today’s cars , and yes, better quality fuel means better fuel mileage. The real damage to modern vehicles related to fuel is the fuel system itself, fuel pumps, injectors, filters etc.

True ... I was using the vehicle mileage stat to “prove” that the fuel Quality isn’t uniform in my locale ... put some of this sub-par fuel in your 2-stroke piston ported engine that’s had the compression raised and timing advanced enough ... well ... I’ll leave it to the forum members to extrapolate....

 

[Chainsaw Jim]

The only issue I have with that line of thinking is fuel quality ... maybe a non-issue in your area however in my locale you can literally see 1-4 mpg differences in fuel economy depending on which station you fill up at ! Several of us have tested this on 100 mi highway treks with cruise control set at 65 and observed said results ... if you happen to get low-budget fuel with a higher-compression engine and advanced timing it may be enough to cause damage !

Are you talking about stations selling clear gas? If not then your mythbuster test has no relevance to this discussion.

 

[Frank Rizzo]

Are you talking about stations selling clear gas? If not then your mythbuster test has no relevance to this discussion.

Myth buster test ? Did you read my comment above regarding vehicles getting varying mileage according to which station and brand of fuel they used ? May not be true in YOUR location and the fuel may be fine there ... the relevance is that caca fuel can scrap a completely STOCK Saw let alone a modded one who’s timing has been advanced ... the op asked a question ... why not answer it ?

 

[Frank Rizzo]

What are the advantages of advancing timing especially on ported saws? Reasons? Theory?

Well ...

 

[Westboastfaller]

"Well"^^^

Perhaps? Could be sick or dead too...I mean it has been 5 yrs

 

[Frank Rizzo]

"Well"^^^

Perhaps? Could be sick or dead too...I mean it has been 5 yrs

I blame it all on BS !

 

[blsnelling]

This isn't about what can cause saw failures, it's about the benefits of advancing ignition timing. Bottom line, it's beneficial on many if not most saws.