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Old 11-12-2003, 08:20 PM
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Detonation?

My engine is making a pinging type noise only when it is under load. I can't get it to make this sound when I stand on the brakes and put it under load that way. It only does it from 1,500 RPMs to about 3,500 RPMs as I am driving. I took it to a local machine shop and had the head machinist go for a drive and listen to it, and he says it doesn't sound like detonation or bottom end noise. It acts like detonation in the powerband that you can hear it in, but what is throwing me off is that as the engine warms up more it gets quieter. Usually pinging gets worse as the car warms up.

I have my timing at 34o total and I have tried retarding the heck out of it. I went down 8o on the initial and there is absolutely no change in the sound. My compression is at 11:1 but I have done a lot to keep it out of detonation, and untill now it hasn't pinged at all. This sound started after I changed my keepers and retainers on my valvesprings. They used to making a clacking noise that I did get rid of, but this new pinging type noise is driving me nuts.

I know at 11:1 I am pushing the limits on California's 91 octane winter additive gas. Worse case scenario would be running a cam with a little higher duration, but I would like to try to keep the cam that is in there now. Anyone have any ideas?

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Old 11-12-2003, 08:33 PM
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Are your new retainers hitting on the valve guides or bottoming out the inner spring or damper? Retainers come in many installed heights and inner I.D.s
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Old 11-12-2003, 09:19 PM
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No, they are clear. Also, if they were hitting I would be able to hear the clacking noise with the car in park. I can only hear it while driving and in gear.

Does pinging ever get quieter as the engine warms up?

Last edited by lluciano77; 11-12-2003 at 09:27 PM.
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Old 11-12-2003, 10:04 PM
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Try this, get a spray bottle, fill it with water, get the car to operating temp, remove the air cleaner, and give the car some throttle and hold it at a steady RPM, set the bottle to stream, and spray a good dose of water to it, occasionally nail the throttle and take a look behind you to see if any black soot comes out, it could be that the carbon has built up enough on the piston tops and with the higher compression ratio is creating enough cylinder tempature for it to detonate regardless of where you set the timing. the later timing can cause it to detonate worse in some cases since it creates higher cylinder tempatures. this is just something to try to see if the problem goes away. if it does, you can add a water injection system, or just add a good octane booster per fill up.
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