Pinging Noise on 76 K10 350 Engine

[ArmySgt97]

First off, I have a 76 K10 with a 350, Edelbrock Performer intake, Edelbrock Performer 600 cfm Carb and headers. This weekend I

adjusted the Valve lash in accordance with my chilton manual because I had a bit of ticking and a friend said that I needed to adjust

that before I adjusted my carb. Anyway, get the lash and I still had a tick, only now it started to get a little louder.Then I started to

adjust the Carb. I read a post that said to adjust the Idle/Mixture screws all the way in and then come out 2 1/2 turns, then start it and

adjust it until I got the highest possible RPM's and then lean it out for a 20 rpm drop. I did that I still had the tick only now it was a little

more like a ping. So I figured I needed to adjust the timing. I dont have a light nor could I find a cheap old style one so I decided to time

it by ear and by vaccuum. I advanced the timing to about 18 on the vaccuum gauge, shut it off and then tried to start it. It was really

hard to start, kinda like a dead battery but then it would fire and idle smooth. So I retarded the timing from 18 to about 16 on the

vacuum gauge and it idles nice, starts good but this dang pinging is getting worse. I messed with the carb a bit and that didnt help.

Tonight I get in the truck to go to the store, start it up and Im getting this kinda wierd knock from the bottom end. So I get under their

and it seems like its coming from the flywheel ( Im missing the bottom half of my bell housing so I can see the Torque converter and

Flywheel). As the engine warms up though it goes away. So I get in, put it in reverse and Im getting this annoying ping, but not real loud

and it only does it in reverse. As im driving Im hearing that pinging now and as I rev the engine it sounds like marbles or shaking a spray

and then the ping in Idle. I put some octane booster in the tank thinking it may be the gas and no luck. So I decide to pull into a parking

lot and try to adjust the timing. As Im advancing and retarding the ping gets a little worse. I cant get it to go away by retarding the

timing at all. And it is more pronounced at certain RPM's. I dont hear it as much when I get on the throttle but I can really here it when

I give it just a little throttle. When I am coming to a stop I dont hear it until I come to a full stop and then I here it again. The thing

that is killing me is the truck is running just fine. The idle is good, it picks up real good when I get on it and there is no stumbling or

anything in any RPM range. Its starts just fine and runs real good, I just have this bad pinging. I have recently replaced the plugs, wires,

fuel filter, air filter, changed the oil and fixed a leak in the oil pan gasket and front seal. BTW the guy I bought the truck from said that it

has an after market cam which I can belive because it idles like it has a mild to mid cam lope. I couldnt tell you lift or druation of the

cam though if it really has one. Please someone give me some advice and help me out. Sorry this is long but I wanted to be descriptive

as I could about every thing that I have done. I read that a lean fuel mixture could cause a detonation ( or Ping, same thing as far as I

understand). Do I maybe have the fuel mixture too lean? Do I need to maybe make it more rich and then try to do the timing again? Do I

need to try to adjust the Valve lash again? BTW I tried to adjust the lash while it was running by backing the rocker nut off until I heard

a decent tick and then tightening it till it stops and then going an additional 1/4 to 3/4 of a turn as per a GM mechanics advice but I

really didnt feel comfortable with it so I followed the instructions of the Chilton manual. Ok Im done now, sorry so long but this is really aggrevating

me. Any and all help is greatly appreciated. Thanks

Brian

[Irish_Alley]

could it be a push rod? maybe distributor cap might not be on right i would check to see were the sound is coming from with a screw driver or stethoscope then go from there

[Marc]

I can't see it pinging at idle.  I would check to make sure the torque converter is bolted tightly to the flex plate.  I'd also check to make sure that the plug wires are routed correctly and triple check that the wires go to the right plugs.  We have a Power Wagon with a 400 that had a noise and stutter in it when we got it.  Checked the wires twice and they looked fine, checked a third time and two wires side by side on the cap were reversed. 

[Lt.Del]

collapsed lifter

[ccz145a]

Check that your spark plugs are tight.

[ArmySgt97]

Well I had a friend from work listen to the noise for me to see if he could figure out the pinging. Come to find out, the noise is not

pinging from the valve train or any kind of spark knock or detonation. The noise is coming from the bottom of the engine. So at first we

were thinking a knocking rod or wrist pin. Come to find out, the bolts that connect the torque converter to the flywheel are loose.

whew!! I thought that I was looking at a engine rebuild for sure. So I tightened them up and the noise went away for a little while. I

gradually came back but is not nearly as bad this time. I crawled under the vehicle to verify the noise and it is definatley coming from

the flywheel/torque converter area. So I suppose that the bolt or nuts are backing off. Do those bolts and nuts just finally wear out and

not hold anymore? Another thing I noticed is that the nuts are not self locking and there is no lock washer or anything on there. Just

regular 9/16th nuts. I would imagine that with all that rotation that their should be a self locking nut or a lock washer on there. So I

guess what Im getting at is  a: Is this a common problem? and b: replacing the nuts and bolts should fix the problem right? and c: Is

their supposed to be a self locking nut or a lock washer down there? I will definatley be putting locktight on the new hardware when I do

get it replaced.  Thanks in advance for any help and thank you marc, SgtDel, ccz145a and Irish_Alley for your suggestions.

[Irish_Alley]

when i changed my girlfriends at the time now wife's trany i forgot to put anything on there and sure enough they backed off, her mom put bad gas in it and the truck kept on stalling unless you gave it gas so she had the bright ideal "she was there only with my wife" to rev the engine to about 4-5k and think it would clear it out, well shortly after that the noise started it was the bolts i thought she blew it up. her dad climbed under the truck took the bolts out and put clear finger nail polish on them and it acted like lock tight now 6 years later no noise. another home remedy to use clear finger nail polish on chiggers, jiggers, and lock tight.

[ArmySgt97]

Well I put the new hardware but it turns out that the flywheel is cracked and its causing it to wobble back and forth enough to make all that racket. I bought the new flywheel yesterday and was going to put it on today but it is raining like crazy and I have no room in my garage to do it due to an 86 K10 in peices in there. Guess Ill have to do it this week some time at the Auto Skills Center on Post!!!