Mopar Muscle Association UK

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 timming will have it's 5 degrees put back on once sorted..

Manifold blow...loose plugs, start there

I'm going to suggest that the head gasket has gone between those two cylinders,so it's now cross-firing. All your symptons sound like the common prob on old L/Rover 21/4 engines,which seem to go on pots 3 and 4. Either the gasket had gradually burnt away or there is some distortion on the head-poss localised overheating or wrongly torqued head bolts. Head may then need a skim

Manifolds have been skimmed but I'll check the plugs. Could help expalin why two plugs side by side eliminate the noise when pulled in turn.

I hope it's something simple (cheap) for a change..

Heads have just been recently skimmed and new Fel Pro gaskets installed just recently. No overheating or excessive use to warrant a leak..

No loose plugs and the manifold is tight and was skimmed as I said.

Could it be a sticking/cracked lifter? Mine has rhodes lifters I believe..

Only other expensive thing I can think of is broken top piston ring come up past the top land ,embedded in piston and tapping the head,have had it happen once on a ford 1600e . Obviously the noise its proportionate to engine revs. Piston looks like it's been centre punched all over,bores usually deeply scored. Sorry,I'll go and hide

Cheaper suggestions most welcome!!!

I now know with your luck why you say Mopar Money Pit..

Cheers anyway, lets hope not, doesnt sound that bad and doesnt do it all the time..

Broken valve spring?

Sounds like a job for the endoscope!

Where's Blue when you need him?

Gavin (and anyone else!) .This link is interesting. It wont cure the problem but might help with diagnosis

http://remanufactured-engines.com/page4 ... osis%20101

Before panic, do the basics, pull the plugs and check them carefully, comp test wet & dry, check everything around the head is tight, look for signs of an exhaust blow, pull the cover and check valve heights, look for broken springs or dampers, moved collets, check the lifters etc

I think you may be have it. I have looked at the head under the car and there is a small trace of oil/water where the haed flares slightly in the middle. Not sure though yet..

Valve train seems all OK as far as I can tell..

Damn!! Just had them skimmed two months ago. Head gaskets is not one of the jobs I can do though I'm afraid. I'm just good at driving them and then breaking them. Compression is 10:1 with alloy heads which should be no problem.

I've heard that tuned small blocks are prone to blow gaskets due to reduced head bolts compared with the big blocks..

Make sure that you are using the correct gasket for alli heads

The Edelbrock heads also require the use of the Fel-Pro Racing head gasket with the pre-flattened, steel o-ring

NOT std gaskets