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What does pinging sound like? --- SOLVED!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Blazer_Boy, Apr 14, 2002.

  1. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Hey y'all, still tunning my motor and haven't a clue what pinging sounds like (yeah I know this is like the billionith post on this, but nobody replies /forums/images/icons/frown.gif. The motor is a 355 using stock flat tops and 64cc vortec heads, about 9.5:1 compression. It has an aluminium intake and three core radiator. The distributor has the Mr. Gasket mechanical advance kit and I am using one light spring, and one medium springs, its kind of their generic reccomendation to use those. The advance can is 15 degrees and is hooked up to full manifold vacuum.

    The deal is that if I bring up to a mammoth hill and am moving pretty good, I'll have the SM465 in 1st or 2nd. I have the window down and while it's pullin the hill it kinda sounds like diesel when its cold, kinda of a steady knock. Its not a violent feeling or noise, just a noise blended in with the over top exhaust that I have. It doesn't do when I'm on the flat ground or flyin' up a medium hill. I have the initial timing at 8 degrees BTDC.

    Is that just normal lugging noise or what. Should I go over to ported vacuum? The springs all right? Should I use less vacuum advance?

    Thanks a bunch if you can help me. I was out tunning it and the gas gauge that said 1/4 tank was actually empty and I had to walk. What a day!

    -----------------------------------------

    Where I last left off was I went out with my friend to take a fast moven ride in the new truck and turned out to be a medicore ebarassment. The poor little truck was running 210 with the heater and 235 without and made for one warm ride in 80 degree weather. I also left a giant size oil slick in front of his house when I got him. I floor borded it and bogged, hmm, wierd. Took it down to an old parking lot and was pulling cookies in the gravel and it died. I blamed it on timing and yanked off the #1 wire to hook the timing gun up. The crimp pulled off the wire, d'oh. It wouldn't start no matter what I did. We had to walk alllll the way back to his house to go get gas. Then I had to go back home to get a plug wire. I then limped home in it and began to here that noise.

    I tried to make a limiting plate for my vac advance and it ran worse with it, hmm. I then was lucky enough to find a BRAND NEW adjustable vacuum advance laying in a bucket of rusty parts outside my uncle's garage. It was someone's junk from years ago and that new advance was in it! I timed it up to 8 BTDC and put the advance at about half limit. It ran even worse?! Tons of dead spots and lugging at low RPMs. I backed it off some, and then a little more, a little better performance. I've got it back off quite a bit now and it runs a hell of alot better. It needed more advance because I was running 8 before to keep kicking at bay when starting. Everything is almost perfect. I'll take it in to have the quadra - jet professionally tuned and have everything check to make sure its kosher.

    While I was pouting about not having it running right, a pin hole leak in my rad tank started up again and began to spray everything. I was so ticked I took the rad down to be done and they did a marvelous job. They straighten the fittings, flushed it with some fancy chemicals and fixed that little hole. I also changed the fan clutch and it now runs around 190. The pan was leaking because somebody used the wrong seal under the timing cover when they put it on (I was off painting my damper). That one wasn't my fault and I happen to keep my left over gaskets and now that problem is solved because I installed the larger sized gasket. Thanks for the advice and especially about the temp having a large effect. I have no kicking at start and my lugging noise was due to a lack off advance. Once I get it reved the mechanical advance kicked it in and that why I had dead spots in a narrow low RPM range. I had it going with the timing light on and gave the throttle a tug and the timing jumped, so the mechanical advance is working A-OK. Now its gonna be terror on 4 wheels, hahaha.
     
  2. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Re: What does pinging sound like?

    I guess what you describe sounds like pinging. It generally occurs at mid-throttle, like when you press the pedal a little bit harder going up a hill. One of the causes can be too much timing.

    If you back off the throttle going up the hill, does the pinging go away?
     
  3. BorregoK5

    BorregoK5 1/2 ton status

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    Re: What does pinging sound like?

    Pinging has a deisel type sound, like tools vibrating in a metal can or like your valves are spontaniously and erraticly tapping. You usually set the mechanical advance springs with the vacuum advance bypassed trying to acheive maximum advance with no ping and your static advance at spec. With too much mechanical advance, you'll tend to get ping near full throttle. Then you can set your vacuum advance (if you have a limiting plate and adjustable diaphram) to get maximum vacuum advance without part throttle ping. I'd use ported vacuum so your idle stays low as opposed to manifold vacuum which will advance your timing at idle and make it idle high (if you adjust the idle down in this scenario you may get a lul off part throttle).
     
  4. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Re: What does pinging sound like?

    I don't know, I'm to afraid to try it again, haha. As I remember, is the motor is wound up, like in a lower gear, than its no problem. If you've driven a manual and you shift a tad to early, its sounds a little luggy and I can hear it during that. I thinking about buying and adjustable vacuum setup, replace the stock weights, and use the springs they give in the vacuum kit. I'm sure it has to be too much vacuum advance, at lower RPMs the engine pulls more vacuum and that may explain why I'm hearing this a low speeds while lugging. As long as I'm flying, I can't hear it.
     
  5. mike reeh

    mike reeh 1/2 ton status

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    Re: What does pinging sound like?

    it sounds like marbles bouncing around inside the engine... the sound a manual tranny makes under a load could be mistaken for the same thing.. you know when you are in a gear and you press forward on the shifter, it amplifies the sound? both that sound and pinging could be referred to as a "cold diesel"......

    the pinging almost always comes on right at full throttle when the secondaries open.. when you have your foot ALL the way to the floor is when it will be the worst. Ive found its easier to hear with the windows closed... even with loud exhaust, its pretty hard to miss it

    mike
     
  6. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Re: What does pinging sound like?

    With a standard I guess the pinging would be worse at full throttle, but with an auto you can put the pedal to the floor and downshift which generally gets rid of the pinging.....
     
  7. OU812

    OU812 Registered Member

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    Re: What does pinging sound like?

    Back off on the timing a little and drive it under the same conditon, walla what you heard before that is now gone was the sound of your motor "pinging".
    By the way what altitude are you at? What grade fuel are you running? Who decided what your compresssion ratio is?
     
  8. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Re: What does pinging sound like?

    Here is what you are trying to achieve. The best amount of advance is somewhere between 32 and 36 degrees total. Most chevy's like about 8 degrees initial timing at the crank. Now you need to determine how much advance your vacuum advance can is giving you. Once you have that figured out then you add the vacuum advance and the initial together and then adjust with the proper springs so that the mechanical advance only gives you the amount of the difference. You will need a vacuum pump and a dial adust timing light to do this. Also you want your vacuum advance hooked up to ported vacuum not manifold vacuum.

    For instance.
    8 degrees initial advance + 12 degrees in the vacuum can = 20 degrees, so you need somewhere between 12-16 degrees in the mechanical weights to give you the recommended 32-36 degrees total.
     
  9. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Re: What does pinging sound like?

    Cool, keep the posts comming, even if it is just a tid bit comment. So basically if I don't know whether I'm hearing it or not, I should be drooling cause I'm already brain dead /forums/images/icons/laugh.gif. The sounds that are being described are a little lighter in tone than what I'm hearing. I'm begining to think that maybe it is standard tranny noise. There's no jerking or anything while this is going on, If I mash it, then it just throws you back in the seat and keeps moving. I am leaning towards ported vac now because what is the point of having all that advance at little throttle and lower RPMs. More throttle and turning the motor faster would seem more logical to have the curve kick in.

    I had the vac can unplugged for a time to test it when I got it running and it never missed a beat, no vibratation, just LOUD exhaust. Hell, I had it way advanced because I was using the old stlye damper with the newer timing cover (corrected timing tab is now in place) when I was first hot rodding it. I couldn't make the damn thing idle unless I mashed it because the manifold vacuum with the original 20 degree can was creating a huge advance at idle. I still didn't hear any tools in a can noise on the test runs. I guess that 91 octane is good stuff.

    Third gear kinda sucked for full throttle, didn't throw me back in the seat but still ran good during the mechanical only test. The noise is no where near erratic when, it goes along with the motor turning. I have to have the windows down and my head hanging out to definetly hear it. This is one steep hill and I was pulling up. So basically I will defintely know when this happens, instead of my little mind games that make say, I thought I heard something.
     
  10. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: What does pinging sound like?

    Ported vacuum causes detonation...I'd never recommend that. As you add throttle (thus increasing load) it increases the timing. That's dumb, and detonation prone.

    A properly curved setup with full vacuum is best because it will allow it to crank with little resistance, idle good, and will help the engine run cooler, and allow you to add timing in the mechanical without worrying about the vacuum (because under heavy throttle, vacuum advance will be completely out of the equation).

    I have been told you've got to find a way to limit mechanical timing or it'll run amuck. There are ways to make stops so it only advances so far. Go to Chevytalk.com, go to the performance forum, and read up on posts by, "Ignitionman". That guy knows his stuff.

    In order to set up the mechanical advance correctly, you'll need to disconnect the vacuum entirely. Just use the vacuum advance to improve idle quality and give you more timing at a light throttle cruise...that will improve fuel economly drastically.
     
  11. BorregoK5

    BorregoK5 1/2 ton status

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    Re: What does pinging sound like?

    Hmm, my ported vacuum on my Q-Jet follows the exact same characteristics as the manifold vacuum. The only difference in them is that at idle the ported vacuum does not advance, but as soon as throttle is slightly applied, it completely opens to manifold vacuum. If you manage load with vacuum then it makes sense to have your highest vacuum set to total advance and retard the advance to cetrifugal timing at no vacuum( which is wide open throttle). If your cetrifugal timing weights and spring tensions are matched to provide as much advance through the rpm band as your setup can take advantage of then at any rpm you can increase load and effectively match the retard to compensate. A limiting plate within the distributer is used to set the maximum amount of advance it should deliver while the adjustable diaphram is used to curve its sensativity to vacuum changes. By increasing the amount of vacuum it takes to hold the advance at it its maximum setting you create a response curve you can match to your engines capabilites and create a very efficient power plant.
     
  12. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: What does pinging sound like?

    I didn't say it wouldn't work, just voicing my opinion.

    Can you email me that chart? My box is clear now.
     
  13. BorregoK5

    BorregoK5 1/2 ton status

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    Re: What does pinging sound like?

    You just had the operation of the vacuum advance backward, an increase in load would decrease the advance as vacuum fell. Everything else you said was right on the money and good advice. but... you did say it was "dumb"/forums/images/icons/crazy.gif.

    I'll send up those specs tomorrow, they are on my work computer. Did you get out muddin this weekend?
     
  14. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: What does pinging sound like?

    Hell no. My truck hasn't moved since December 21, 2001. Some nutcase woman took out the whole left side of it and hit the front of the left rear tire, braking the leaf spring. It has a bent frame, too. I need to get it back together, hopefully this summer. Unfortuately, I just don't have the money to work on it right now.

    That said, I'm having 4 wheeling withdrawl. I really, really miss my K10. By the time I drive it again, I'll not only have to re-learn how to drive it, it'll be a 4 speed! It's going to be weird but exiting too.
     
  15. BorregoK5

    BorregoK5 1/2 ton status

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    Re: What does pinging sound like?

    Ouch! Were you in it when it happened??? How did it hold up inside? Sorry to hear that!
     
  16. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    Re: What does pinging sound like?

    If you're still not positive that it is detonation...
    Go buy an octane booster or two and dump em in the gas tank... and go do your test again... take it to the same place and do the same thing.
    If it doesn't "ping" anymore you know you need to run a higher octane fuel...
    Pay attention to the temperature when this is happening! 190 vs. 210 will make a HUGE difference in detonation.

    Or try retarding the timing back a couple of degrees.
    I had to back off the timing a few degrees to get my BBC to quit pinging. Just as a quick fix i bumped the inital from like 13 to 11 and that brought the total from about 34 to 32.
    Now i need to play with the springs and set the total advance so i can bump the inital timing back up to 13 so it'll idle better.
     
  17. BorregoK5

    BorregoK5 1/2 ton status

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    Re: What does pinging sound like?

    Ryan is right on! You can also run a cooler plug which shrouds the spark a little and slows the burn process just enough to cure infrequent pinging.
     

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