UPDATE: Is My Engine Pinging?

[scottiec]

UPDATE: I used a piston stop as recommended, and my TDC is dead on. I also unplugged and capped the vacuum advance to make sure it wasn't advancing the timing too much. No change in sound, which makes me think that I really just need to change my driving style and not lug the motor. Just because it's a v8 doesn't mean that it makes a ton of torque everywhere. I guess I was just used to my 06 gto I had, where it wanted you to skip to 4th gear at 25 mph and be at 1000rpm. I'll keep the revs above 1900 when cruising now.

Also, I'll be meeting up with a local forum member here who has a lot more experience than I do. We will drive the car and listen for any funny sounds to make sure everything is up to snuff. I like this engine I build and want it to work for a very long time!

Thanks again everyone!


Hi Guys,

Got the new motor in the car and all seems to be well so far. The whole pushrod carburetor v8 thing is new to me. Between the volume of the side pipes, roller rockers, and other valve train noise, I have no idea if my engine is pinging. Can someone help me determine if it is? Here are some details of the engine.

I rebuilt a 302 short block, trick flow track heat 170 heads, brawler 600cfm double pumper, ford b-cam, comp roller rockers. My intial timing is at 12 BTDC and my total is 32 BTDC. My air/fuel ratios are right where they need to be. Nothing leaning out, correct powervalve is in, overall running smooth. Rear end is a 3.31. Oh! and the springs in my dizzy are the heavy ones, so I'm all in at 3000-3500 rpm.

When I am in 4th or 5th gear at 1500-2000 rpm or so, and give it gas, I hear the chugging along noises that I would expect from a v8. In fact, it made the exact same noises with the last motor (same cam but gt40 p heads). From reading online, I have heard wildly differing descriptions of what pinging actually sounds like.

When I downshift, to say 3rd gear, I don't hear the same noises, but I can't tell if that is because the engine is spinning twice as fast. Am I lugging the motor by being under 2000 rpm?

I know this is vague, but I just really want to make sure I am not damaging this engine. The new engine fixed the horrible issues I was having previously and it feels good to be able to move onto bodywork and paint.

Thanks gang!

[Mike N]

Hard to hear pinging with the loud exhaust but most people describe it as sounding like shaking a coffee can with a couple of nuts and bolts in it. Sounds like a sharp knocking sound.

From the description of your set up and timing I see nothing that would indicate that you would be experiencing pinging.

[scottiec]

Hard to hear pinging with the loud exhaust but most people describe it as sounding like shaking a coffee can with a couple of nuts and bolts in it. Sounds like a sharp knocking sound.

From the description of your set up and timing I see nothing that would indicate that you would be experiencing pinging.

Thanks Mike! I agree, my set up should be pretty safe. Just wish I could know for sure

[NAZ]

Agree, hard to hear knocking (or pinging if you're old school) with loud exhaust. If you do hear it it's probably severe.

If you need to be sure there are several knock detection tools on the market. Some are portable and some are designed to be mounted permanently. Some detect a knock; some with qualify it as light, moderate, and heavy; and some will quantify and record events. The prices can be a few hundred dollars to several thousand depending on what you need. Do a internet search and you will find a variety of tools.

[TexasAviator]

what is your quench built to? IE what is your headgasket thickness? What is your deck height in relation to your pistons, what is your piston design? What is your compression? What gas are you using?

[scottiec]

what is your quench built to? IE what is your headgasket thickness? What is your deck height in relation to your pistons, what is your piston design? What is your compression? What gas are you using?

Quench is right around .047. Stock trw forged pistons. 93 octane.

[Ducky2009]

Do you know the compression ratio... with a variety of different components, sometimes it's hard to determine. If you're not sure..... What is your ideal speed? If you're about 1200 RPM, the cam and compression ratio combination wants to deliver upper end power. The higher the compression ratio (and 3.31 gears), the more pinging you'll get when bogging the engine down. My first question was answered.... 93 octane. High compression needs good gas. Try retarding the timing to 4-5 BTDC. It wont run as well but if the pinging reduces/goes away, you'll have to live with your condition. High compression doesn't like low RPM and that high of a gear ratio. When you're finished, set the timing back.

Question.... Is your distributor a vacuum advance type? Did you disconnect the vacuum advance (and plug it, carb end) when setting the timing?

[scottiec]

Do you know the compression ratio... with a variety of different components, sometimes it's hard to determine. If you're not sure..... What is your ideal speed? If you're about 1200 RPM, the cam and compression ratio combination wants to deliver upper end power. The higher the compression ratio (and 3.31 gears), the more pinging you'll get when bogging the engine down. My first question was answered.... 93 octane. High compression needs good gas. Try retarding the timing to 4-5 BTDC. It wont run as well but if the pinging reduces/goes away, you'll have to live with your condition. High compression doesn't like low RPM and that high of a gear ratio. When you're finished, set the timing back.

Question.... Is your distributor a vacuum advance type? Did you disconnect the vacuum advance (and plug it, carb end) when setting the timing?

Hey ducky,
So I was coming up with two different numbers for my compression. In the calculator, I entered all of my my information for the motor and was coming up 10:1. However, what doesn’t make sense is that stock 302s from that year came with 9:1 from the factory. The only changes I made to effect compression was a smaller combustion chamber (58cc instead of factory 64ishcc) and my head gasket (which is actually slightly thicker than stock!!). So if I am calculating my compression from what it should have been from the factory, my motor should be at 9.3:1 right now. Sorry for the long and confusing answer.

Either way, I don’t know If my motor would be considered high compression. I’ll pull back my timing and see what happens!

EDIT: yes I plugged my vacuum advance when setting timing.

[CraigS]

Try driving w/ the vac advance plugged. At one time I had similar sound and found I had something like 25 deg of vac advance. My theory was that the advance didn't go away quickly enough as the gas pedal went down. I adjusted it to max at 10 deg and cured the noise.

[scottiec]

Try driving w/ the vac advance plugged. At one time I had similar sound and found I had something like 25 deg of vac advance. My theory was that the advance didn't go away quickly enough as the gas pedal went down. I adjusted it to max at 10 deg and cured the noise.

Craig great point. I’ll give that a shot first. I just need to plug the carb side correct?

[NAZ]

Your first post indicated that you weren't sure what "pinging" sounded like, therefore, not sure if you are actually experiencing it. You described a condition at low RPM and under load as a "chugging" noise. Pinging is a very distinctive noise and I don't think anyone that has heard an engine pinging would describe it as a chugging noise. I've ridden lots of Harleys with loud exhaust and lugging them along at low RPMs under load make a noise you might describe as "chugging" but that is not pinging. If you've heard an older Cummins diesel in a Dodge truck run it sounds somewhat similar to a gas engine ping.

So my advice is to first get aquatinted with what pinging sounds like or you are chasing a ghost. If you do actually hear your engine pinging then you have a couple of good ideas above to help you address the issue. But if you really don't know what you're listening for making the adjustments recommended above won't really help you. This is one of those tuning things that only experience can guide you since you are relying on the sense of hearing. You might search YouTube for an example of an engine pinging -- seems everything you ever wanted to know can be found on YouTube.

[Gumball]

Another thought on "chugging." I'm not a fan of putting load on performance engines at low rpm for fear of pounding the rod bearings. My suggestion is that it's okay to cruise at 1500 - 2000 rpm, but if there is a need to do more than very slight changes in throttle pressure, it's best to downshift (with a rev match) and then accelerate. After getting to your new speed, you can again upshift to cruise rpm.

For comparison sake, I have a 347 with 10.5:1 compression, one of the Ford letter cams, a pertronix-equipped old-school Ford mechanical advance dual point distributor (similar static and all-in advance numbers), and a blueprinted 650 double pumper. My car has a T5, so I typically don't use 5th gear until I'm doing around 60 mph, which in that gear equates to around 1600 rpm. At lower speeds on the typical two-lane roads around here (40-45 mph), I stay in 4th gear right around 2000 rpm. I try to get the revs up to 2500+ before giving it any more than part throttle - 3000+ for anything approaching full throttle.... and even then, I ease into it smoothly; i.e., nothing abrupt.

[scottiec]

Your first post indicated that you weren't sure what "pinging" sounded like, therefore, not sure if you are actually experiencing it. You described a condition at low RPM and under load as a "chugging" noise. Pinging is a very distinctive noise and I don't think anyone that has heard an engine pinging would describe it as a chugging noise. I've ridden lots of Harleys with loud exhaust and lugging them along at low RPMs under load make a noise you might describe as "chugging" but that is not pinging. If you've heard an older Cummins diesel in a Dodge truck run it sounds somewhat similar to a gas engine ping.

So my advice is to first get aquatinted with what pinging sounds like or you are chasing a ghost. If you do actually hear your engine pinging then you have a couple of good ideas above to help you address the issue. But if you really don't know what you're listening for making the adjustments recommended above won't really help you. This is one of those tuning things that only experience can guide you since you are relying on the sense of hearing. You might search YouTube for an example of an engine pinging -- seems everything you ever wanted to know can be found on YouTube.

Naz,
You are right. I am pretty unfamiliar with a lot of these noises. I think I should someone with experience take a listen before I jump to conclusions.

Another thought on "chugging." I'm not a fan of putting load on performance engines at low rpm for fear of pounding the rod bearings. My suggestion is that it's okay to cruise at 1500 - 2000 rpm, but if there is a need to do more than very slight changes in throttle pressure, it's best to downshift (with a rev match) and then accelerate. After getting to your new speed, you can again upshift to cruise rpm.

For comparison sake, I have a 347 with 10.5:1 compression, one of the Ford letter cams, a pertronix-equipped old-school Ford mechanical advance dual point distributor (similar static and all-in advance numbers), and a blueprinted 650 double pumper. My car has a T5, so I typically don't use 5th gear until I'm doing around 60 mph, which in that gear equates to around 1600 rpm. At lower speeds on the typical two-lane roads around here (40-45 mph), I stay in 4th gear right around 2000 rpm. I try to get the revs up to 2500+ before giving it any more than part throttle - 3000+ for anything approaching full throttle.... and even then, I ease into it smoothly; i.e., nothing abrupt.

Chris,
This is really helpful. I honestly think my motor just isn't a fan of things below 2000 rpm. I am probably expecting too much "low end v8 grunt" from something that I didn't necessarily build to be that way. And when ever I am around 50 mph, I feel like in 4th gear it is yelling at me to shift. But it is still too slow of a speed to be in 5th. I just need to get used to it and see where the motor is happy.

I still plan on disconnecting the vacuum advance and see if that does change something. If sounds change, then I know I am hearing something.

[Boydster]

This is a good video on pinging / detonation / spark knock. Its the chain rattling, sand chewing, small-ballbearings-bouncing-around sound you here as this F150 is accelerating.

https://www.youtube.com/watch?v=6xTWHJADFe8

Maybe this will help you determine what you're hearing. Oh, and pinging will almost always happen at low rpm, high load.

[scottiec]

This is a good video on pinging / detonation / spark knock. Its the chain rattling, sand chewing, small-ballbearings-bouncing-around sound you here as this F150 is accelerating.

https://www.youtube.com/watch?v=6xTWHJADFe8

Maybe this will help you determine what you're hearing. Oh, and pinging will almost always happen at low rpm, high load.

Boyd,
This is extremely helpful. Thanks for sharing this!

[NAZ]

Spark Knock or engine ping

Try this video, it's better sound quality and a very severe case of pinging.

[scottiec]

Spark Knock or engine ping

Try this video, it's better sound quality and a very severe case of pinging.

Thanks naz. After listening to these examples, I want to say I have some mild pinging going on. As soon as this rain stops I’ll take the car out and confirm. It also sounds like I should treat this motor differently than my daily driver in terms of low rpms and engine load.

I’ll report back. Hopefully by Sunday. Thanks again guys! This has been really helpful.

[NAZ]

OK, so you're sure that you are experiencing pinging. I suspect it's your driving style but set that aside for now and let's check the basics. Your base timing, total timing, and all-in by RPM settings are reasonable. But have you verified that your pointer is zero at actual TDC? Don't just assume it's correct -- I've seen them out enough to cause issues. In fact you could be significantly more advanced than your timing light shows and not know it if you haven't verified TDC. Use a TDC tool to verify your pointer is aligned to TDC before you make any other changes. I make mine from old spark plugs but they are cheap enough to buy them from outlets like Summit Racing or Jegs. It simply screws into the #1 spark plug hole and stops the piston just before TDC. Pull all the plugs and turn the engine by hand until the piston contacts the TDC tool. Make a precise mark on the VD aligned with the pointer. Rotate the engine the other direction until the piston contacts the TDC tool and precisely place another mark aligned with the pointer. Carefully measure the half-way point between the two marks and that is exactly TDC. Verify that your pointer is aligned with that center point mark and make corrections as necessary.

If the pointer was zero at TDC then you can start addressing the pinging issue. Start by pulling base timing out a couple degrees at a time until the pinging is mostly gone (I really don't worry much about a slight ping for a second or two) but be careful not to pull too much timing out. Retarding the timing will eventually do two undesirable things: 1) reduce power, and 2) create lots of heat in the exhaust manifold -- enough to cause some serious problems.

If you can't prevent the pinging after ~4-degrres retarding the base timing then you probably should accept that your driving style needs to change. Think about it. If you had an auto trans vehicle cruising along in OD at 1500 RPM and floored the throttle you'd expect an instant kick-down into at least the next lower gear. And an auto trans with it's torque convertor slip and torque multiplication (as much as doubling the engine torque) is way more forgiving than a stick that is direct coupled to the engine. You're asking a lot from an engine that does not have knock sensors and computer control of the timing and AFR. So if you have verified that the timing is what you think it is and you can't eliminate the pinging when flooring the throttle in 4th or 5th gear at 1500 RPM with your tall rear end ratio then the only reasonable explanation is you are asking more from your engine than it is capable of.

[scottiec]

OK, so you're sure that you are experiencing pinging. I suspect it's your driving style but set that aside for now and let's check the basics. Your base timing, total timing, and all-in by RPM settings are reasonable. But have you verified that your pointer is zero at actual TDC? Don't just assume it's correct -- I've seen them out enough to cause issues. In fact you could be significantly more advanced than your timing light shows and not know it if you haven't verified TDC. Use a TDC tool to verify your pointer is aligned to TDC before you make any other changes. I make mine from old spark plugs but they are cheap enough to buy them from outlets like Summit Racing or Jegs. It simply screws into the #1 spark plug hole and stops the piston just before TDC. Pull all the plugs and turn the engine by hand until the piston contacts the TDC tool. Make a precise mark on the VD aligned with the pointer. Rotate the engine the other direction until the piston contacts the TDC tool and precisely place another mark aligned with the pointer. Carefully measure the half-way point between the two marks and that is exactly TDC. Verify that your pointer is aligned with that center point mark and make corrections as necessary.

If the pointer was zero at TDC then you can start addressing the pinging issue. Start by pulling base timing out a couple degrees at a time until the pinging is mostly gone (I really don't worry much about a slight ping for a second or two) but be careful not to pull too much timing out. Retarding the timing will eventually do two undesirable things: 1) reduce power, and 2) create lots of heat in the exhaust manifold -- enough to cause some serious problems.

If you can't prevent the pinging after ~4-degrres retarding the base timing then you probably should accept that your driving style needs to change. Think about it. If you had an auto trans vehicle cruising along in OD at 1500 RPM and floored the throttle you'd expect an instant kick-down into at least the next lower gear. And an auto trans with it's torque convertor slip and torque multiplication (as much as doubling the engine torque) is way more forgiving than a stick that is direct coupled to the engine. You're asking a lot from an engine that does not have knock sensors and computer control of the timing and AFR. So if you have verified that the timing is what you think it is and you can't eliminate the pinging when flooring the throttle in 4th or 5th gear at 1500 RPM with your tall rear end ratio then the only reasonable explanation is you are asking more from your engine than it is capable of.

Naz,
This is why I love this forum. Thank you so much for this detailed write up and putting things into perspective. I will verify my TDC mark for sure. Question though. How do you accurately measure the midpoint from the two marks I make when using the TDC tool?

[NAZ]

I use a thin machinist scale

[Railroad]

Other than trying to accelerate in too high of a gear, I think something else might be going on.
His timing is very conservative, base, total and rpm.
When stated, fuel ratios are right where they need to be, it made me feel like an O2 sensor was used to attain a target fuel ratio. Most tech articles will show 14.7 being ideal and many novice tuners shoot for this number. I would like to hear the fuel ratio or what mods were done to get there.
Just chasing the rabbit, not shooting at anyone.

[scottiec]

Other than trying to accelerate in too high of a gear, I think something else might be going on.
His timing is very conservative, base, total and rpm.
When stated, fuel ratios are right where they need to be, it made me feel like an O2 sensor was used to attain a target fuel ratio. Most tech articles will show 14.7 being ideal and many novice tuners shoot for this number. I would like to hear the fuel ratio or what mods were done to get there.
Just chasing the rabbit, not shooting at anyone.

Hey railroad. Yes I used an innovate lm2 with an 02 sensor in my side pipe. My afr is 13.7- 14.2.

[Railroad]

IMO you are a whole number too lean. What jets came in the carb and what are you running? Any power valve changes?

I think you are leaving a lot of power on the table with the very conservative ign timing you are running now.

I would richen up, pending no ping, base timing OK, total advance 32 to 36* depending upon what your heads like, all in by 2600 rpm. You can fudge these numbers up and down as your car responds.

good luck,

[NAZ]

You don't indicate at what RPM and load those AFR numbers are from and it does make a difference. 13.7 - 14.2 would be on the lean side at WOT under load and I would expect that to affect power output. Best power will usually be found closer to 12.5. However, if you can run between 13.0 & 15.0 on the idle circuit and still have instant throttle response you'd probably be happy with that and I'd like to see the leaner side of that range if performance allows. The idle circuit is active at much higher RPM than most folks realize. But be advised that some combinations may not like to idle at anything leaner than mid 12's and still have good response so don't get too wrapped around the axle on AFR numbers on the idle and mid range -- find what your combination likes. As for WOT under load you'll want to be fatter than 13.7 to start with and I usually target 12.5 and tune from there for best power.

[scottiec]

Ahhhh sorry was typing on my phone. Meant to say that the 13.7-14.2 is my idle. At WOT I am around 12.7. Sorry!!

[NAZ]

Great, sounds like you're on top of your tune. It'll be interesting to see what's causing that ping. Let us know what you find.

[scottiec]

Great, sounds like you're on top of your tune. It'll be interesting to see what's causing that ping. Let us know what you find.

Will do. Thanks again guys

[scottiec]

update:

Drove the car tonight. Tried it with the vacuum advance plugged in and with out. No difference. The only difference was the car felt a little lazier on tip in and light accel without the vacuum advance, which is to be expected. Next I will be checking for true TDC to make sure that’s not causing and problems. This could just be one of those things where my motor doesn’t like living under 2000 rpms.

[scottiec]

update:

Drove the car tonight. Tried it with the vacuum advance plugged in and with out. No difference. The only difference was the car felt a little lazier on tip in and light accel without the vacuum advance, which is to be expected. Next I will be checking for true TDC to make sure that’s not causing and problems. This could just be one of those things where my motor doesn’t like living under 2000 rpms.

[scottiec]

Update above