Oldschool Timing Adjustment
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
You are misunderstanding the difference between accurate and correct. For example, I could lock the timing at 10 degrees and confirm (with a timing light), accurately, that it is at 10 degrees. However accurate that might be, it would not be the correct timing to maximize combustion efficiency and power/mileage.
Feel free to dismiss any of my knowledge and experience in engines and engine controls, but I have a simple question: How did you arrive at the correct timing curve for your engine?
Feel free to dismiss any of my knowledge and experience in engines and engine controls, but I have a simple question: How did you arrive at the correct timing curve for your engine?
Pro
Joined: Jun 2009
Posts: 613
Likes: 3
From: Fleetwood PA
No misunderstanding here. From what I've read from my piston mfg, head mfg and other knowledgeable mfg's and folks like Lars, 34* is better for my setup. Therefore, I'll call that the "correct" timing for my engine. Now to get that timing "accurate", I will use a timing light and not a vacuum gauge. I have a Street damper and by design, it can't "slip" out of adjustment. My timing tab was tweaked to match 0* on the damper with the # 1 piston set at top dead center with a degree wheel and a dial indicator gauge. My distributor gear was replaced and shimmed to 0.010". My roller cam has 0.050" play. That said, my timing can be set accurately for the correct 34*. What I am doubting is that you can set the correct timing accurately with a vacuum gauge. Btw, I never quoted Lars about the use of a timing light or vacuum gauge as someone else posted. So this is not drawing Lars in like the other post by 540rat. Lars can comment if he so wishes on the method he uses to time an engine. In closing, if one does time their engine using a vacuum and then checks it with a timing light, well, what's that saying?
You have very specific info on all aspects of you motor and you know where you want it set....Not everyone does. If you said to me" I want this car timed at 34* then I would use a timing light as that's the only way to set and confirm a specific number.
If you gave me an car with no specifics and just said it runs like crap can you make it better, I'd start with a vacuum gauge to help check engine health, carb settings, and timing.(along with compression and leak down gauges) Vacuum will tell you where the car wants to be, and the timing light will give you what that number is. If the distributor is ever removed for any reason, then I'd have a set number for reference and would just use the timing light to get it back to that setting.
I agree timing lights are a very important tool to have. As is a dwell meter(for points cars) and a vacuum gauge. All serve their purpose, and when used together can give the best results.
Cruising
Joined: Jul 2013
Posts: 14
Likes: 0
Troll
[QUOTE=whitehause;1584756082]Why do you keep posting if you have nothing to add? Oh wait, are you a professional troll? I've always wanted to meet
Sticks and stones. Troll. Really that's the best you got. I'm guessing ur quite a bit older then me be happy a 23 year old is into vettes and will try and carry on long after ur gone no subs, Toyotas, no Hondas just my vette, if I post and you don't like it well that's just to bad.
Troll kinda has a nice ring to it
Sticks and stones. Troll. Really that's the best you got. I'm guessing ur quite a bit older then me be happy a 23 year old is into vettes and will try and carry on long after ur gone no subs, Toyotas, no Hondas just my vette, if I post and you don't like it well that's just to bad.
Troll kinda has a nice ring to it
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
No misunderstanding here. From what I've read from my piston mfg, head mfg and other knowledgeable mfg's and folks like Lars, 34* is better for my setup. Therefore, I'll call that the "correct" timing for my engine. Now to get that timing "accurate", I will use a timing light and not a vacuum gauge. I have a Street damper and by design, it can't "slip" out of adjustment. My timing tab was tweaked to match 0* on the damper with the # 1 piston set at top dead center with a degree wheel and a dial indicator gauge. My distributor gear was replaced and shimmed to 0.010". My roller cam has 0.050" play. That said, my timing can be set accurately for the correct 34*. What I am doubting is that you can set the correct timing accurately with a vacuum gauge. Btw, I never quoted Lars about the use of a timing light or vacuum gauge as someone else posted. So this is not drawing Lars in like the other post by 540rat. Lars can comment if he so wishes on the method he uses to time an engine. In closing, if one does time their engine using a vacuum and then checks it with a timing light, well, what's that saying?
You say that you have determined the optimal timing setting using information from "piston mfg, head mfg and other knowledgeable mfg's and folks like Lars", and then you use a timing light to set your timing at that point. What you're doing amounts to making an educated guess at what the timing should be, and setting it there. With a vacuum gauge, you can actually get some feedback from the engine to see what it likes. It may not be perfect, but I think it's better than guessing.
Even Lars doesn't usually quote specific numbers when making timing recommendations, he will usually give a range. 34-38 degrees, for instance. It's up to you to tune it.
Scott
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
[QUOTE=Rker;1584756285]
Sticks and stones? LOL! Nice comeback...if you're, like, five years old...
Anyway, personally, I am glad to see people your age who are into older cars like these. Just, please don't put a big, park-bench wing on the back of your 'vette, OK?
Scott
Why do you keep posting if you have nothing to add? Oh wait, are you a professional troll? I've always wanted to meet
Sticks and stones. Troll. Really that's the best you got. I'm guessing ur quite a bit older then me be happy a 23 year old is into vettes and will try and carry on long after ur gone no subs, Toyotas, no Hondas just my vette, if I post and you don't like it well that's just to bad.
Troll kinda has a nice ring to it
Sticks and stones. Troll. Really that's the best you got. I'm guessing ur quite a bit older then me be happy a 23 year old is into vettes and will try and carry on long after ur gone no subs, Toyotas, no Hondas just my vette, if I post and you don't like it well that's just to bad.
Troll kinda has a nice ring to it
Anyway, personally, I am glad to see people your age who are into older cars like these. Just, please don't put a big, park-bench wing on the back of your 'vette, OK?
Scott
Pro
Joined: Jun 2009
Posts: 613
Likes: 3
From: Fleetwood PA
Sticks and stones. Troll. Really that's the best you got. I'm guessing ur quite a bit older then me be happy a 23 year old is into vettes and will try and carry on long after ur gone no subs, Toyotas, no Hondas just my vette, if I post and you don't like it well that's just to bad.
Troll kinda has a nice ring to it
Troll kinda has a nice ring to it
I really doesn't matter how old you are, and I really don't care. If you need help with a problem there are a lot of people willing to help, but starting off being a d-bag isn't the best way to get it.
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Brett Foote
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
Just out of curiosity, how do you like to adjust your idle mixture screws? Do you just arbitrarily set them to a certain number of turns out, which you have deemed optimal from doing research, or do you use a vacuum gauge, or do a lean roll, or what? I use a vacuum gauge, and I adjust them for highest vacuum, then turn them in, maybe 1/8 turn. I don't just set them to where I think the engine wants, I set them to where the engine shows me it wants. Using a vacuum gauge.
You say that you have determined the optimal timing setting using information from "piston mfg, head mfg and other knowledgeable mfg's and folks like Lars", and then you use a timing light to set your timing at that point. What you're doing amounts to making an educated guess at what the timing should be, and setting it there. With a vacuum gauge, you can actually get some feedback from the engine to see what it likes. It may not be perfect, but I think it's better than guessing.
Even Lars doesn't usually quote specific numbers when making timing recommendations, he will usually give a range. 34-38 degrees, for instance. It's up to you to tune it.
Scott
You say that you have determined the optimal timing setting using information from "piston mfg, head mfg and other knowledgeable mfg's and folks like Lars", and then you use a timing light to set your timing at that point. What you're doing amounts to making an educated guess at what the timing should be, and setting it there. With a vacuum gauge, you can actually get some feedback from the engine to see what it likes. It may not be perfect, but I think it's better than guessing.
Even Lars doesn't usually quote specific numbers when making timing recommendations, he will usually give a range. 34-38 degrees, for instance. It's up to you to tune it.
Scott
Lars did make a comment in another post that on some newer aluminium heads that optimal timing can be reduced a few degrees for optimum performance. Others, e.g. mfg's, have also stated this. So the 36* optimum considered by most for the sbc does not apply for me as I have previously stated. Anyway, the OP asked why or why not. I said use a timing light because its more precise. Don't see what all the fuss is about, really.
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
With a vacuum gauge, of course. Adjusting your idle mixture is not setting your timing and I'm sure you know that. I use the vacuum gauge for other analysis as it's a must tool but not for timing.
Lars did make a comment in another post that on some newer aluminium heads that optimal timing can be reduced a few degrees for optimum performance. Others, e.g. mfg's, have also stated this. So the 36* optimum considered by most for the sbc does not apply for me as I have previously stated. Anyway, the OP asked why or why not. I said use a timing light because its more precise. Don't see what all the fuss is about, really.
Lars did make a comment in another post that on some newer aluminium heads that optimal timing can be reduced a few degrees for optimum performance. Others, e.g. mfg's, have also stated this. So the 36* optimum considered by most for the sbc does not apply for me as I have previously stated. Anyway, the OP asked why or why not. I said use a timing light because its more precise. Don't see what all the fuss is about, really.
It's a free country, you can set your timing any way you like, I suppose. It's starting to sound like you will not be swayed, so I guess we'll just have to agree to disagree.
Scott
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
For all you keyboard commandos that insist that vacuum isn't a useful method.
Just for fun,
Connect a vacuum gauge to any non computer car so you can read it while driving.
That along with a tach, take notes of your observations at different rpm and load levels. Change your timing, drive for a few more days taking notes. Keep repeating.
Some of you guys might learn something about vacuum.
You can even do it with an FI ECU engine if it's distributor based and you move it far enough off the computer's control limits.
Just for fun,
Connect a vacuum gauge to any non computer car so you can read it while driving.
That along with a tach, take notes of your observations at different rpm and load levels. Change your timing, drive for a few more days taking notes. Keep repeating.
Some of you guys might learn something about vacuum.
You can even do it with an FI ECU engine if it's distributor based and you move it far enough off the computer's control limits.
Pro
Joined: May 2011
Posts: 722
Likes: 58
From: Karlsruhe (Germany)
What i don´t understand is:
If you set the idle timing with vacuum, how can you be sure it´s at optimum at higher rpm´s?
Every distributor has a different advance range, so if you set it to optimum at idle, it may perform better at medium load, but may not be perfect at full load.
Setting the curve just for maximum output power could be the reason why it does not perform so good at medium load.
So I think both meanings are right.
If you set the idle timing with vacuum, how can you be sure it´s at optimum at higher rpm´s?
Every distributor has a different advance range, so if you set it to optimum at idle, it may perform better at medium load, but may not be perfect at full load.
Setting the curve just for maximum output power could be the reason why it does not perform so good at medium load.
So I think both meanings are right.
Le Mans Master
Joined: Aug 2006
Posts: 7,425
Likes: 1,559
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Details details!
http://automotivemileposts.com/garage/v2n8.html
Paragraph 7 is wrong!
About the idle mixture screws
CW= in for lean and
CCW= out for rich.
Paragraph 7 is wrong!
About the idle mixture screws
CW= in for lean and
CCW= out for rich.
Pro
Joined: Jun 2009
Posts: 613
Likes: 3
From: Fleetwood PA
http://automotivemileposts.com/garage/v2n8.html
Paragraph 7 is wrong!
About the idle mixture screws
CW= in for lean and
CCW= out for rich.
Paragraph 7 is wrong!
About the idle mixture screws
CW= in for lean and
CCW= out for rich.
Cruising
Joined: Jul 2013
Posts: 14
Likes: 0
Your a guy who likes to snipe from a distance and you try and make it personal we call that by a different name, I have no grip with u so take a hike ill post what I want not what you want me to. If I need help with my 52 year old vette I'll ask someone who and their are people who will help and aren't offended by a little humor ill bet you love Fox News uh uh
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Your a guy who likes to snipe from a distance and you try and make it personal we call that by a different name, I have no grip with u so take a hike ill post what I want not what you want me to. If I need help with my 52 year old vette I'll ask someone who and their are people who will help and aren't offended by a little humor ill bet you love Fox News uh uh
Scott
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
What i don´t understand is:
If you set the idle timing with vacuum, how can you be sure it´s at optimum at higher rpm´s?
Every distributor has a different advance range, so if you set it to optimum at idle, it may perform better at medium load, but may not be perfect at full load.
Setting the curve just for maximum output power could be the reason why it does not perform so good at medium load.
So I think both meanings are right.
If you set the idle timing with vacuum, how can you be sure it´s at optimum at higher rpm´s?
Every distributor has a different advance range, so if you set it to optimum at idle, it may perform better at medium load, but may not be perfect at full load.
Setting the curve just for maximum output power could be the reason why it does not perform so good at medium load.
So I think both meanings are right.
Scott
Cruising
Joined: Jul 2013
Posts: 14
Likes: 0
Scott
[QUOTE=scottyp99;1584756528]
Scott
Ok I hear you no wing, not my thing anyway, but I don't hate on those that like that sort of thing and neither should you or anyone else, it's a choice a personal one. I think there are a few stuff shirts on the forum and I like pulling their chains. Timing lights no timing lights vacuum timing no vacuum timing, whoa again to each own. These arguments don't produce viable factual information just opinions based on individual experiences. So really interested parties who want the information are left with a variety of choices because grown men bicker so yes sticks and stones you have to bring yourself down to their level and add a little humor, it's not a discussion in my view it's a few people posturing trying to convince the rest of us they have the right answers, I still don't have the factual information from these subject matter experts to make a decision on what is the best way to set up timing for max performance and drive ability on the street. Attack the issue not the person
Ok I hear you no wing, not my thing anyway, but I don't hate on those that like that sort of thing and neither should you or anyone else, it's a choice a personal one. I think there are a few stuff shirts on the forum and I like pulling their chains. Timing lights no timing lights vacuum timing no vacuum timing, whoa again to each own. These arguments don't produce viable factual information just opinions based on individual experiences. So really interested parties who want the information are left with a variety of choices because grown men bicker so yes sticks and stones you have to bring yourself down to their level and add a little humor, it's not a discussion in my view it's a few people posturing trying to convince the rest of us they have the right answers, I still don't have the factual information from these subject matter experts to make a decision on what is the best way to set up timing for max performance and drive ability on the street. Attack the issue not the person
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
[QUOTE=Rker;1584760992]
Scott
Ok I hear you no wing, not my thing anyway, but I don't hate on those that like that sort of thing and neither should you or anyone else, it's a choice a personal one. I think there are a few stuff shirts on the forum and I like pulling their chains. Timing lights no timing lights vacuum timing no vacuum timing, whoa again to each own. These arguments don't produce viable factual information just opinions based on individual experiences. So really interested parties who want the information are left with a variety of choices because grown men bicker so yes sticks and stones you have to bring yourself down to their level and add a little humor, it's not a discussion in my view it's a few people posturing trying to convince the rest of us they have the right answers, I still don't have the factual information from these subject matter experts to make a decision on what is the best way to set up timing for max performance and drive ability on the street. Attack the issue not the person
Ah, but sometimes the person is the problem.
It's the internet, man, you have to learn to sift through all the BS to get to the good stuff. That means using your critical thinking skills, not just parroting what you have heard others say. It's harder than it sounds, because we all do it, subconsciously. It takes a conscious effort to do your own thinking.
Scott
Scott
Ok I hear you no wing, not my thing anyway, but I don't hate on those that like that sort of thing and neither should you or anyone else, it's a choice a personal one. I think there are a few stuff shirts on the forum and I like pulling their chains. Timing lights no timing lights vacuum timing no vacuum timing, whoa again to each own. These arguments don't produce viable factual information just opinions based on individual experiences. So really interested parties who want the information are left with a variety of choices because grown men bicker so yes sticks and stones you have to bring yourself down to their level and add a little humor, it's not a discussion in my view it's a few people posturing trying to convince the rest of us they have the right answers, I still don't have the factual information from these subject matter experts to make a decision on what is the best way to set up timing for max performance and drive ability on the street. Attack the issue not the person
It's the internet, man, you have to learn to sift through all the BS to get to the good stuff. That means using your critical thinking skills, not just parroting what you have heard others say. It's harder than it sounds, because we all do it, subconsciously. It takes a conscious effort to do your own thinking.
Scott