Engine pinging

J

j5ball

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Over the last couple weeks there is a bad pinging that has gotten worse. The ping is coming from the carb. I did notice it got really bad after I put in a new tank of regular gas. So I added some octane boaster but the Ping is still there. I have read the octane boosters do not really help. I think I am going to siphon out my tank and fill with high octane gas. See what happens here. Also. There are lots of new additions to my engine. New 4 bbl intake (was a 2) and 4bbl carb (was a 2). New water pump. New chain and sprockets. Went to HEI system Engine is the original 350. The original set timing is 10 dtdc. With all the new stuff, would the timing needed to changed?
 
Pinging doesnt coming from a carburetor it comes from the engne block, are you sure it is pinging? You should be able to hear it while driving and accelerating or going up a hill. What year engine do you have, if anything newer than 1970 it will run on regular unless something has been change to your timing curve. What HEI distributor did you install, GM, aftermarket, stock, modified, etc? Do you own a dial back timing light?
 
Engine is 1968. HEI is some after market I picked up at one of the car shows
 
Here is the sound coming out of my car . . the noise appears to come from the carb . .appears is the key word . . WTF is this ?

http://youtu.be/LKCOJA9anU0
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All I hear is that loud ticking sound and that doesn't sound like detonation (pinging). Towards the end of the video it looks like its your fuel linkage making that noise. Pinging sound more like a bunch of loose pebbles bouncing around. And if your engine is stock you probably have #17 heads on it. So your compression is probably in the mid to low 8's which shouldn't give you any pinging issues. Unless you changed the heads or pistons.
 
That ticking sound is the pinging sound - poor phone audio system. Yes, like some pebbles bouncing around. Stock heads and pistons. I moved the HEI around from 6 degrees to 14 degrees . . no change. Still pinging. I did pulL the driver side set of plugs. The plugs are black. And I would say I have less than 300 miles on these plugs. Something is going on. Just not sure what.
 
OK I'm not a real expert but I believe its caused by -

too much compression, which you shouldn't have

overheating - check your coolant, water pump

too much timing - you said you set it from 6-14 degrees. Check your vacuum advance. Maybe its giving you too much. Also check you mechanical advance springs.

and I think bad gas can do it too. If so, you'll have to drain out the bad gas.

These are things I've read about. I don't have much 1st hand experience with this. Maybe Melsg5 can be more help.
 
It sounded to me like it was a slight backfire through the carburetor. When you set the timing you are doing it with the vacuum advance to the distributor disconnected? Is the timing mark bouncing around alot when you set the timing? Have you done a compression test? If you hold you hand over the carburetor do you feel pulses of air/gas when the noise occurs?
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yes. There is a slight backfire when I hit the throttle. Vaccum advance is disconnected and plugged. timing does not bouce around - very steady. Have not done a compression check yet. Yes - there are pockets of air and gas coming from the carb.

I just came back from an old school mechanic. He thinks its either a bad rod or the rocker arms are too tight or too loose. He is thinking one of the rocker arms became too loose. How to focus in on the issue? He said I can take each of the spark plugs wires off each spark plug one at a time. When the sounds disappears I know which piston the issue occuring at. I can then pull the gasket and look at the rocker arms for that piston and do some tests for too loose or too tight.

Thoughts or additional suggestions???? Thanks . . .JIMB
 
Stock Pontiacs do not have an adjustable valve train, unlike Chevrolet. You torque the rocker arm nut to I believe 30 ft/lb and that's it. If there was any kind of wear in the valve train I would expect to hear a clattering noise from one of the valve covers. You can pull the covers and make sure all the nuts are tight and you can try the pull the plug method to check for a cylinder that is not firing. In the end I think you need to perform a compression test and at the same time you will be pulling the plugs so you can verify they are gapped correctly, with an HEI you can use .045, and see if any of them are fouled.
 
Update. I had another problem when I was attempting to test the pistons for where the ping in my engine was originating from. The test was: Take a plug wire off a plug, thus disabling any firing from the piston, and when the pinging stops you know which piston is creating the pinging. I got through testing 2 pistons then the car just stopped running. There is an issue with this method. I have a HEI system. You should not remove a plug wire from the plug and run the engine when you have a HEI system. The spark will go back into the distributor and fry the ICM (ignition control module.) Oh well. several hours and days later I found the problem. Bought a new ICM, installed, and car now starts again. Yes, pinging still there. I did a compression test on the engine. 110 / 108 / 109 / 110 / 115 / 120 / 105 / 121. Compression looks good. I guess I will have to remove the valve covers and watch the rockers. Any other suggestions for diagnosing the pinging issue ?
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Listening again to the video, it almosts sounds like something is hitting a rocker arm cover, it's a " tinny" sort of sound. Sorry about the icm. In hindsight with the engine off disconnect one plug wire at the plug and
grounding that terminal to the block would be the way to go but I dont think that would help in this case. That way you wont fry the icm. Can you take a piece of rubber hose hold one end against your ear and hold the other end against each rocker cover to see which one is producing the noise.
 
Took off valve covers. I have one rocker that I can easily push on the top of the rocker (at the push rod) and it goes down about 1/2 inch. I DON'T think this is suppose to happen. I think something is broken here. All (except for one) rockers have oil sitting in the bottom lip of the rocker. Except for one. Thats right. The rocker that has NO oil in the lip of the rocker is the one I can easily push down at the push rod end. Thoughts ??? before I pull the head.
 
It sounds like the lifter has failed. You dont pull the head at this point, you remove the intake manifold and valley pan to determine what happened.
 
Can I replace the lifter without taking off the head
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Pulled intake and valley pan. Pulled the lifter I thought was bad. And yes. Bad. And there is another lifter that is about to go. So, I am pulling all the rods and lifters and replacing them all. Rods are not bent or bowed. Seem to be fine but I am going to replace them anyways. Now the Question -While I am here, what else should I be doing since I have almost everything on the top apart. What can I clean everything with? Sea foam? What else should I be checking/replacing since the intake and valley pan are off? The rockers seem to be fine. But, should I go ahead and replace them also .. While I am here. Thanks . . JIMB
 
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