Chattering noise.. search narrowed down.

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demong

demong

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I've recently experienced a chattering, almost pinking noise coming from the passenger side rocker cover. This happens only when the car is under load accelerating or kickdown etc.

Not being all that technical the car (340 Demon) was taken off to a rolling road where pinking/detonation was diagnosed not before trying to jump off the rollers and spit them out several times. The timing was backed of 5 degrees in total. Guess what, drove off and nothing had changed.

The thing is this noise is as bad when the car is cold as when it is hot and it is not affected by the weather etc when pinking usually is.

I did a few runs today on a quite road pulling each plug wire in turn until the noise actually went when I pulled the second wire back from the front of the car passenger side. It also made no noise when this was re-connected and the third wire back was pulled??

It seems when the load was taken off either of these two cylinders the noise stopped. I've now sort of isolated the noise and just need to know your thoughts on what it could be. Suggestions please Gentleman..

Oh and yes the timing will have it's 5 degrees put back on once sorted..
 
Sounds familiar. I had a pecking noise in my 340 and during tearbown for rebuild, a piston skirt was located in the oil pan.
 
I would think that it would be a lifter especially since when it is cold it would be louder. When the motor gets hotter the metal parts expand. If you have hyd. lifters and it makes noises either hot or cold you can get one of those stethoscopes and find out which cylinder its coming from.
 
Has the car been sitting for a while? Reason that i ask is that when i started driving my car before the resto, after it had been sitting for 15+ years, it started to develop a ticking noise at the front of the engine. It was a little diferent though, it would go away under a load (or maybe i couldn't hear it because it so darn loud @ wot) but it was definatly noticable under light throtle acceleration up to about 3500-3800 RPM. When my dad and i pulled the mill a couple weeks ago and started taking it apart, we found that the rod bearings on cylinders 1 and 2 were flaking apart. The only thing we can think of is that the acidity in the oil broke down the bearing surface while it sat. Then when we started driving it again, it slowly started to kill the bearings at start up. This created enough play that the #1 & #2 pistons were coming up and hitting the head. This is my 2 cents
 
They are Moroso plug wires. Surprised they may cause this sort of problem though only under load although they do virtually touch sometimes.

The car rarely sits longer than a week. One minute the noise wasnt there then it was.. I have heard that tuned small blocks (370bhp) suffer head gasket failure due to the reduced number of head bolts used compared with a big block?

This engine was built about 2 yrs ago using all new quality parts assembled by the top Chrysler guy in the UK who looks after the Montiverdi collection. ARP head bolts, Fel Pro Head gaskets etc, new heads.

Most recently had the alloy edelbrock heads skimmed and compression up to 10:1 so unsure really. Car ran fine and this has just started.

Cheers guys..
 
:scratch: I wonder if it might be an exhaust leak at the manifold around the #4 and #6 cylinders?? Sometimes that will sound like a lifter ticking, and it's usually louder under load. Just something else to check.
 
Exhaust leak would be my guess too. They can sound like a tick. Fire up the engine (dead cold) and stick you hand around the area, you can usually feel it leaking. But you have to be quick as the exhaust heats up quickly
 
I've checked the plugs and wires and they are all ok. Swapped them all around and the noise is still there. I will change the exhaust manifold gasket next although it is a new Felpro one with less than 200 miles on it. I've checked it visually and can see nothing wrong. This chattering noise under load is loud enough to be heard outside the car.

The noise just sound sounds too chattery for a manifold leak but I would like to be proved wrong. I had a 70 Cuda with a leaking manifold and although that ticked away you could hear it all the time.

I'll be away for a while on business so look forward to any replies.

Cheers guys.
 
Are you sure it's coming from under the valve cover?
Torque converter bolts make a funny noise when the back out a little and start hitting the inspection cover. Easy and quick just to pull the inspection cover off and make sure they are'nt coming loose.
The cover will also have neat gouges in it.
 
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