318 Rocker Clatter

[MOPARJ]

I Have A 73 Duster With A 318 And 80,000 Miles. Its Runs Extremely Well With Good Oil Pressure(65 Psi Cold, 17psi Hot In Drive{750 Rpm} And About 21psi In Neutral When Hot{950 Rpm}, Rises To 40 Psi At Warm 2000 Rpm). It Has A Edelbrock Performer Intake And 600 Carb. I Just Had A Comp 260 Cam And Lifters Put In. Runs Great With Great Low End Torque. My Question Involves The Rocker Clatter That I Have. Two Rockers On The Right Cylinder Bank Have The Slightest Amount Of Play In Them(from Just Wear I Would Imagine), Which I Think Is Making The Clatter When The Motor Warms Up(almost Sounds Like A Exhaust Mainfold Leak, But Isnt). I Know Mopar Rockershafts And Assemblies Are Near Indestructable, Even Stock. The Noise Isnt Bothering Me And Eventually When I Get More Money(lol), I Will Replace All Of Them. I Dont Think Its Doing Anything, Harm Wise, But Does Anyone Think This Poses A Serious Problem?? I Run Shell Rotella 15w-40 Oil, Which Has Excellent Zinc Levels. Comments Are Greatly Appreciated. Keep Those Mopars Rollin'!

 

[C130 Chief]

I have had a bit of grief with Comp lifters myself recently (on a Buick 350). I am living with it until I get real bored and pull the intake. Basically 2 of my lifters bleed off at real low RPM. I am guessing you may be suffering the same fate. But here are some other things to check if you want to make a semi-scientific diagnosis.

Bent pushrods: It happens, and if your 318 ever suffered a cam gear failure, bent pushrods are almost guaranteed.

Worn rockers/shaft: If the shaft had grooves worn into it and you took it off the engine, forget ever making it totally quiet again, even if you get all the rockers in their original location. I wouldnt think wear on an 80,000 mile engine wouldn't be too severe as long as the oil was changed somewhat regularly. If you put your finger on the rockers at idle and push sideways a bit does the noise stop? You can carefully make a rocker a little "wider", but dont get carried away. If only two have more wear or play than the rest, I would start asking myself why.

Collapsed lifter: As I said above, I have had problems with Comp lifters right out of the box. Try to isolate which lifters are ticking, and have a hepler crank the engine with the valve cover off. Stop the noisy valve at full lift and watch. Does the lifter bleed down in less than 30 seconds? If so, your lifter is junk.

Wiped cam lobe: Yeah, this is the ugly one nobody wants to think about, but it happens. Pull the valve covers and make sure you are getting the same lift on all valves (intakes may be differnt from exhaust, but all 8 of each should be the same). You will find the above mentioned collapsed lifter real quick doing this. No need to bust out a dial indicator, a steel ruler with a couple sharpie marks will give you a basic "big picture" type diagnosis.

Exhaust leak: As you said, it sounds like an exhaust leak. Are you absolutely sure it isnt? If pulling spark plug wires makes it change notably, suspect exhaust.

 

[MOPARJ]

I Also Forgot To Mention That It Has Comp Springs Too. Even Before The Cam Swap, It Made The -rocker- Noise, Just Quieter Than With The Cam. I Dont Think It Is The Lifter.when It Is Warm, It Makes Very Slight Lifter Noise, But Nothing To Worry About. I Reiterate That It Runs Great, With No Previous Gear Or Timing Chain Failures. Thanks For Any Other Input.