The ping is the sound of preignition; i.e. the air/fuel is igniting before the piston reaches the top of its travel.
CK5
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Timing a motor by ear...
- Thread starter GsxrMike
- Start date
The ping is the sound of preignition; i.e. the air/fuel is igniting before the piston reaches the top of its travel.
original balzer
1/2 ton status
This argument can go on and on. Just like adjusting a carb with a vacuum gauge or by ear. Bottom line is some people can do it some cant. The topic of the thread was timing by ear. I wont argue this anymore.
Randy92782
1 ton status
I've always thought of the ping being the infamous sparkknock.Meaning it's advanced too much. Or the the other way around. Can't remember
British Slave
1/2 ton status
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In the old days, it was easy to time by ear. Today I don't think it is possible due to the computer. I tried, it didn't work. Truck ran like crap. By the book, no problems.
Technical Information Bulletin Rev. G 9-11-05
How to Set Your Timing for Peak Performance
by Lars Grimsrud
Lafayette, CO
This tech paper will discuss setting the timing on a Chevy V8. This procedure also applies to other GM V8s.
The procedure outlined here differs from the Service Manual, and is based on my years of experience doing this work in the quickest, least painful, most economical way while keeping the level of quality high. It is recognized that other people will have different methods of doing things, and may disagree with specific methods and procedures that I use.
How to Set the Timing
When you think about it, setting the timing at idle speed makes no sense at all: You don’t operate your car at idle, and timing changes as the rpm changes. Fact is, the timing spec at idle speed is provided as a simple way for most people to set the timing, and is not a good procedure for optimum performance.
Small block Chevys (and most other GM performance V8 engines) perform best when the total timing (full centrifugal advance plus the initial timing setting with vacuum advance hose disconnected) is all in by 2,500 – 2,800 rpm and is set to about 36 degrees. If you have an adjustable timing light, this is very easy to check. If you don’t, you need to scribe a 36-degree mark on your harmonic balancer. Here’s how:
Measure the circumference of your harmonic balancer using a sewing tape measure (or other flexible tape measure). Get it as accurate as you can. Take this measurement and divide by 10. The number you get is the distance to 36 degrees. Measure this distance CLOCKWISE from your existing harmonic balancer timing mark as viewed from the front of the engine and place a clear mark on the balancer.
Remove your distributor cap and rotor. If you have a points-style distributor with the stock, factory, heavy springs in place, remove one of the springs. Disconnect the vacuum advance. Install the rotor and cap. Loosen the distributor hold-down clamp bolt just enough so that the distributor can by turned, yet leave it snug enough that the distributor will hold its position.
Start the engine. If you’re using an adjustable timing light, set the light to 36 degrees advanced. Now rev the engine while observing the timing marks with the light. You will notice that the stock line on the balancer will move up towards the timing plate as rpm increases. Continue to increase rpm until the line does not move any further (centrifugal advance is “pegged out”). Once the timing is “pegged out,” the line on the balancer should line up with the “0” mark on the timing tab. Rotate the distributor to achieve this.
If you’re using a non-adjustable light, perform the same process, but align your new 36-degree mark with “0” mark on the timing tab.
Shut it down.
Pop the cap and rotor and re-install the spring, if you removed it. Put everything back together, but leave the vacuum disconnected. Start it up. For future reference, make a note of the timing setting at idle. This is your new curb idle timing spec. Now give the engine a few quick rev’s past 3,000 rpm and verify that the full timing (36 degrees) is coming in. If it’s not, you need to change to a softer set of springs until you get full 36-degree advance before 3000 rpm. (NOTE: A stock set of springs will often not allow full centrifugal advance to come in before redline rpm. If you have heavy stock springs installed, don’t rev the engine beyond its limits to try to force full advance in.) I suggest obtaining Mr. Gasket kit part number 927 or 928: Use the gold springs on HEI systems. For points-style systems, use one black spring and one silver spring – these springs will get your total timing all in by 2500-2800 rpm, providing very good throttle response and power. The black & silver spring combo can also be used on MSD distributors if you widen out the spring hook ends.
Hook up the vacuum. Re-set your idle speed and idle mixtures if necessary to lower the idle speed. Now do a road test.
The 36-degree 2500 rpm advance curve is optimum for performance, but may require premium fuel. Lug the car around, and punch the throttle at low rpm while listening for detonation (“engine knock”). If you’re getting any audible knock, you MUST retard the timing. Retard the timing in 2-degree increments until engine knock stops. Engine knock will seriously damage engine components if not corrected. If you get no knock, you may see slightly improved performance at 38 degrees total timing. This is particularly true if you’re running at high altitude.
If you have no engine knock under acceleration, but the car “chugs” or “jerks” at cruising speed (light throttle application), you are getting too much vacuum advance on top of the mechanical advance. You may need to change out the vacuum advance diaphragm with a unit producing no more than 16 degrees of vacuum advance. See my paper on “Vacuum Advance Control Units Facts and Specs” for more info on this.
Your timing is now set for best possible performance. Make note of the new setting, and use this for your future tune-up work.
Lars’ Suggested Timing Specs for GM V8 Performance Applications:
• 36 degrees total timing (vacuum advance hose disconnected), all “in” by 2500 rpm
• 18 degrees initial timing at idle (vacuum advance hose disconnected). Note that it may not be possible to achieve the 18-degree initial spec with the 36-degree total without modifying the distributor advance stop system. It is more important to achieve the 36 total than to hit an exact 18 initial. However, if your initial timing is very low (below 12 degrees) with the 36 total, it is important that you repair or modify your distributor in order to achieve correct engine performance
• 16 degree vacuum advance control unit with a pull-in spec that allows the full range of vacuum advance to be pulled in at the engine’s idle manifold vacuum level. Connect to manifold vacuum for most applications (this will allow the engine to idle with actual timing at idle of 34 degrees).
How to Set Your Timing for Peak Performance
by Lars Grimsrud
Lafayette, CO
“90% of all “carb problems” are ignition timing problems.”
(Lars Grimsrud)
(Lars Grimsrud)
This tech paper will discuss setting the timing on a Chevy V8. This procedure also applies to other GM V8s.
The procedure outlined here differs from the Service Manual, and is based on my years of experience doing this work in the quickest, least painful, most economical way while keeping the level of quality high. It is recognized that other people will have different methods of doing things, and may disagree with specific methods and procedures that I use.
How to Set the Timing
When you think about it, setting the timing at idle speed makes no sense at all: You don’t operate your car at idle, and timing changes as the rpm changes. Fact is, the timing spec at idle speed is provided as a simple way for most people to set the timing, and is not a good procedure for optimum performance.
Small block Chevys (and most other GM performance V8 engines) perform best when the total timing (full centrifugal advance plus the initial timing setting with vacuum advance hose disconnected) is all in by 2,500 – 2,800 rpm and is set to about 36 degrees. If you have an adjustable timing light, this is very easy to check. If you don’t, you need to scribe a 36-degree mark on your harmonic balancer. Here’s how:
Measure the circumference of your harmonic balancer using a sewing tape measure (or other flexible tape measure). Get it as accurate as you can. Take this measurement and divide by 10. The number you get is the distance to 36 degrees. Measure this distance CLOCKWISE from your existing harmonic balancer timing mark as viewed from the front of the engine and place a clear mark on the balancer.
Remove your distributor cap and rotor. If you have a points-style distributor with the stock, factory, heavy springs in place, remove one of the springs. Disconnect the vacuum advance. Install the rotor and cap. Loosen the distributor hold-down clamp bolt just enough so that the distributor can by turned, yet leave it snug enough that the distributor will hold its position.
Start the engine. If you’re using an adjustable timing light, set the light to 36 degrees advanced. Now rev the engine while observing the timing marks with the light. You will notice that the stock line on the balancer will move up towards the timing plate as rpm increases. Continue to increase rpm until the line does not move any further (centrifugal advance is “pegged out”). Once the timing is “pegged out,” the line on the balancer should line up with the “0” mark on the timing tab. Rotate the distributor to achieve this.
If you’re using a non-adjustable light, perform the same process, but align your new 36-degree mark with “0” mark on the timing tab.
Shut it down.
Pop the cap and rotor and re-install the spring, if you removed it. Put everything back together, but leave the vacuum disconnected. Start it up. For future reference, make a note of the timing setting at idle. This is your new curb idle timing spec. Now give the engine a few quick rev’s past 3,000 rpm and verify that the full timing (36 degrees) is coming in. If it’s not, you need to change to a softer set of springs until you get full 36-degree advance before 3000 rpm. (NOTE: A stock set of springs will often not allow full centrifugal advance to come in before redline rpm. If you have heavy stock springs installed, don’t rev the engine beyond its limits to try to force full advance in.) I suggest obtaining Mr. Gasket kit part number 927 or 928: Use the gold springs on HEI systems. For points-style systems, use one black spring and one silver spring – these springs will get your total timing all in by 2500-2800 rpm, providing very good throttle response and power. The black & silver spring combo can also be used on MSD distributors if you widen out the spring hook ends.
Hook up the vacuum. Re-set your idle speed and idle mixtures if necessary to lower the idle speed. Now do a road test.
The 36-degree 2500 rpm advance curve is optimum for performance, but may require premium fuel. Lug the car around, and punch the throttle at low rpm while listening for detonation (“engine knock”). If you’re getting any audible knock, you MUST retard the timing. Retard the timing in 2-degree increments until engine knock stops. Engine knock will seriously damage engine components if not corrected. If you get no knock, you may see slightly improved performance at 38 degrees total timing. This is particularly true if you’re running at high altitude.
If you have no engine knock under acceleration, but the car “chugs” or “jerks” at cruising speed (light throttle application), you are getting too much vacuum advance on top of the mechanical advance. You may need to change out the vacuum advance diaphragm with a unit producing no more than 16 degrees of vacuum advance. See my paper on “Vacuum Advance Control Units Facts and Specs” for more info on this.
Your timing is now set for best possible performance. Make note of the new setting, and use this for your future tune-up work.
Lars’ Suggested Timing Specs for GM V8 Performance Applications:
• 36 degrees total timing (vacuum advance hose disconnected), all “in” by 2500 rpm
• 18 degrees initial timing at idle (vacuum advance hose disconnected). Note that it may not be possible to achieve the 18-degree initial spec with the 36-degree total without modifying the distributor advance stop system. It is more important to achieve the 36 total than to hit an exact 18 initial. However, if your initial timing is very low (below 12 degrees) with the 36 total, it is important that you repair or modify your distributor in order to achieve correct engine performance
• 16 degree vacuum advance control unit with a pull-in spec that allows the full range of vacuum advance to be pulled in at the engine’s idle manifold vacuum level. Connect to manifold vacuum for most applications (this will allow the engine to idle with actual timing at idle of 34 degrees).
GsxrMike
1/2 ton status
Thanks for your responce but I understand the cause of the "ping" but I am not sure what I am looking/listening for. Is the sound/feel of it similar to a miss in the engine? From what i'ver heard/read it is very bad for the motor so I want to make sure I set it correctly. Thanks!
EDIT: Alright I just checked my timing using howdiy's post and I have found that I am running 12* initial timing @ idle with the vacuum advance disconnected and I am running 34* timing at about 3500rpm (I can't see the tach). Does this sound good? Should I try to go to 36* (I run 87 octane)? I should get total advance by 3000rpm right? Maybe I will go set a brick on the tall skinny one on the right to see if I am getting total advance by 3000rpm.
Last edited:
travisc454
Registered Member
x2 i've heard alot of sounds come out of a motor but none of them i would describe as a "Ping". i know its hard to write a sound but can someone try. i find it hard to hear anything over the roar of my old motors. plus my ears have seen some explosions.
original balzer
1/2 ton status
I guess you could call the sound a internal backfire. I would say it moves the exhaust sound into the cylender rather than in the exhaust pipes. It kinda has a knocking sound to it. It will usually show up before you get valve train chatter caused by to much RPM(if you have too much timing advance that is). Its otherwise known ad pre-detonation. Why it was labeled as "ping" I do not know.
The easiest way to describe it is the simple change from a smooth running engine to a choppy running engine.
What it does is as the piston moves up the spark plug fires too soon, witch wants to force the piston back down, BUT the piston HAS to finish going up before it can go back down. It causes tons of undue stress.
So your next question would be: In that case wouldnt you want the timing retarded so it fires just as the piston starts going back down.
The answer is no, and the reason is it takes a certain amount of time to burn all the feul. So Ideally you want to start the burn, as it gets to the final compression that way it gets the most effiiciant burn and the explosion forces the piston back down.
But Ill stop there cuz most of you guys understand the fundamentals of a internal combustion engine.
I hope this helps.
The easiest way to describe it is the simple change from a smooth running engine to a choppy running engine.
What it does is as the piston moves up the spark plug fires too soon, witch wants to force the piston back down, BUT the piston HAS to finish going up before it can go back down. It causes tons of undue stress.
So your next question would be: In that case wouldnt you want the timing retarded so it fires just as the piston starts going back down.
The answer is no, and the reason is it takes a certain amount of time to burn all the feul. So Ideally you want to start the burn, as it gets to the final compression that way it gets the most effiiciant burn and the explosion forces the piston back down.
But Ill stop there cuz most of you guys understand the fundamentals of a internal combustion engine.
I hope this helps.
Not throwing rocks, just asking for my knowledge in case I missed something. Shouldn't you retard the timing if it's knocking? Isn't that in essence tuning by ear? If you are getting pinging at 8*, what else should you do besides timing?
GsxrMike
1/2 ton status
I think what they are trying to say is that you don't want to time a motor without a timing gun. I guess you will always have to use your ears to time it.
Blazer79
1/2 ton status
My 2 cents:
"pinging" makes your engine sound more like a diesel engine or like rattling a can with pebbles inside.
I'm another 'by ear' timing guy. I recall a friend of mine taking his older Grand Prix in for a tune up. They timed to it with a light, and by the book. He got out of the parking lot and it bogged and fell on it's face.
I timed it by ear for him, advance until it pings a touch under load, then back it off a hair...and it friggen screamed again. Took it back to the garage and they checked with a timing light (curiousity) and it was at 18 BTDC on their light rather than the 6 or 8 BTDC the book called for. Obviously the timing chain was getting sloppy...
Each engine has it's very own sweet spot, and if you're willing to mess with it for a while you'll find it. The important thing I found is to make sure the dist is working as it should. Mech weights can get sticky, Vac advance can get fouled up too. Both have a big effect on total timing, and when that timing comes in.
The last gas engine I timed was my old 355 in my K5. Maybe 80K miles on it, new chain, cam etc etc. Wouldn't run right, always had a weird miss. Stripped the dist down and cleaned and replaced everything. The mech weights were so gummed up they didn't move. The vac advance diaphram was full of gas
Fixed those two problems, and found some great power, smoother starting too. Still had a weird miss under load though. Turned out the new Accel wires i had were crap right out of the box. Swapped them for some 8,8 mm Taylor's and the difference was amazing.
Bottom line is, tuning by ear isn't voodoo, but like anything you need to make sure the parts are good first.
Rene
I timed it by ear for him, advance until it pings a touch under load, then back it off a hair...and it friggen screamed again. Took it back to the garage and they checked with a timing light (curiousity) and it was at 18 BTDC on their light rather than the 6 or 8 BTDC the book called for. Obviously the timing chain was getting sloppy...
Each engine has it's very own sweet spot, and if you're willing to mess with it for a while you'll find it. The important thing I found is to make sure the dist is working as it should. Mech weights can get sticky, Vac advance can get fouled up too. Both have a big effect on total timing, and when that timing comes in.
The last gas engine I timed was my old 355 in my K5. Maybe 80K miles on it, new chain, cam etc etc. Wouldn't run right, always had a weird miss. Stripped the dist down and cleaned and replaced everything. The mech weights were so gummed up they didn't move. The vac advance diaphram was full of gas
Fixed those two problems, and found some great power, smoother starting too. Still had a weird miss under load though. Turned out the new Accel wires i had were crap right out of the box. Swapped them for some 8,8 mm Taylor's and the difference was amazing.
Bottom line is, tuning by ear isn't voodoo, but like anything you need to make sure the parts are good first.
Rene
bp71k5
3/4 ton status
I think regardless of how you figure out the "amount" of timing advance you need, having a way to know what the timing is set to once that's done is pretty important.
Once you know that, there's all kinds of things you can learn about how the motor is operating and where to look for problems if there are any.
Once you know that, there's all kinds of things you can learn about how the motor is operating and where to look for problems if there are any.
To me pinging sounds like two chunks of metal tapping against each other lightly. When it occurs, it's always (that I've experienced anyway) in rapid succession, it's not just one sound and it goes away...it occurs until the load on the engine decreases, either by letting off the gas or the road flattens out.
I timed my old truck (305) by ear, and got really good mileage out of it, and was happy with performance. Reality is that timing is a curve, and the engine is not best served by running up timing as high as possible before ping. You could be sacrificing a lot of power and driveability in low or mid range by doing it by ear or "max advance", which is EXACTLY the reason they make tuning kits for mechanical advance, why there are adjustable vacuum canisters, why vacuum advance was, is and can be hooked up two different ways, and why you have always been able to to adjust the distributor physically. Otherwise, there would be no adjustability at all.
You can't do all of that by ear obviously. Not saying you can't tune by ear, you just can't get it tuned in all regards as good as you could with a light. But most people don't go to that extreme anyway, will you? If all your time was spent at one RPM, tuning by ear would have absolutely no downside.
I timed my old truck (305) by ear, and got really good mileage out of it, and was happy with performance. Reality is that timing is a curve, and the engine is not best served by running up timing as high as possible before ping. You could be sacrificing a lot of power and driveability in low or mid range by doing it by ear or "max advance", which is EXACTLY the reason they make tuning kits for mechanical advance, why there are adjustable vacuum canisters, why vacuum advance was, is and can be hooked up two different ways, and why you have always been able to to adjust the distributor physically. Otherwise, there would be no adjustability at all.
You can't do all of that by ear obviously. Not saying you can't tune by ear, you just can't get it tuned in all regards as good as you could with a light. But most people don't go to that extreme anyway, will you? If all your time was spent at one RPM, tuning by ear would have absolutely no downside.
GsxrMike
1/2 ton status
What gives
Alright I test drove the ol' girl again tonight and she still stumbles around 3000rpm
and won't accelerate unless I back off the throttle (about 3/4 instead of WOT) and then she will accelerate. Any other ideas?
Alright I test drove the ol' girl again tonight and she still stumbles around 3000rpm
and won't accelerate unless I back off the throttle (about 3/4 instead of WOT) and then she will accelerate. Any other ideas?
Alright I test drove the ol' girl again tonight and she still stumbles around 3000rpm
Sounds like a typical woman to me. "Don't tell me what to do! I'll do it the way I want to."
Have you checked your fuel filter(s) and pump. Clogged line or bad pump may be starving the truck for fuel under full load. Just a thought. I don't think the pump would do this. I've personally only seen an all or nothing on the pump but...
GsxrMike
1/2 ton status
Sounds like a typical woman to me. "Don't tell me what to do! I'll do it the way I want to."
I don't get it... I've tried pretty much everything everyone has said.
It is definatly not a fuel pressure issue. It has to be in the carb or the ignition...I think
Same occurs at 3000RPM in each gear?
GsxrMike
1/2 ton status
Well I am pretty sure but when it shifts under WOT it doesn't dip below 3000rpm so I couldn't say for sure until tonight when I can go try it manually. Are you thinking it could be something in the tranny?
Blazer79
1/2 ton status
Does it happen only if you floor it? Do you have a Quadrajet? Maybe its the infamous quadrabog you're experiencing? It's just a matter of tuning the screw that tightens the secondary butterflies. I had that problem.
