# Engine Tapping or ticking at certain rpm



## wlbuckles (Apr 3, 2010)

Going thru the gears at a particular rpm I have a clattering noise in my 389. at a lower or higher rpm the sound vanishes. Have a couple of ideas. Any Help ????? Thanks.:confused


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## jetstang (Nov 5, 2008)

Is it valve clatter or pinging. Pinging happens under hard exceleration or load. It won't ping under light throttle. Valve tap usually happens at low oil pressure-- idle. But goes away with RPM.


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## nedorama (Sep 13, 2010)

It could be valve tappet gone bad, or it could be a sign that the engine has higher compression and isn't liking the lower octane gas. 

I had a similar sound, and when they got into the engine, all the bearings were shot. Engine was rebuilt with compression based on today's octane gas.


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## wlbuckles (Apr 3, 2010)

It clatters at idle but goes away like you said with a little more rpm. But the real noise problem is when I lightly go thru the gears and at a certain rpm, say 1500 it has a distinc high pitch rattle, not a ping. The engine is stock and I run 92 octane and a good addative for more octane. Any further advice.


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## geeteeohguy (Feb 2, 2008)

Does it do it in neutral if you go thru the rpm range in the driveway? If so, use a stethescope or listening rod (screwdriver) to pinpoint the noise. Possiible worn rocker arm/pivot, valve noise, rod bearing, lifter, etc. etc.


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## wlbuckles (Apr 3, 2010)

geeteeohguy said:


> Does it do it in neutral if you go thru the rpm range in the driveway? If so, use a stethescope or listening rod (screwdriver) to pinpoint the noise. Possiible worn rocker arm/pivot, valve noise, rod bearing, lifter, etc. etc.


 Yea it does do it somewhat in neutral, but seems to be moreso with a load on. I'm going to take your advise with my scope and check it out. Thanks Gee.


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## Lemans-67 (Sep 7, 2010)

Does it have the rockers on a shaft? I'd guess it's a worn out cam that is giving you problems. I had that happen to my Buick. Extreme low pressure will also cause this but it almost has to be nil. Check valve travel once you figure out which valve is making the noise. It is very noticeable if the cam lobe is rounded. G//L. Jr


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## Rukee (Feb 8, 2007)

Sounds like the rockers need adjusting, to me anyway.


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## wlbuckles (Apr 3, 2010)

I let it warm up, shut it off, pulled the valve covers, put on the oil splatter retainers,started it back up, and adjusted the valves to 25 torque. I have been told to look at the push rods while idling and if they are not rotating then I may have a bad cam. Any proof to this ??? Thanks.


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## jetstang (Nov 5, 2008)

wlbuckles said:


> I let it warm up, shut it off, pulled the valve covers, put on the oil splatter retainers,started it back up, and adjusted the valves to 25 torque. I have been told to look at the push rods while idling and if they are not rotating then I may have a bad cam. Any proof to this ??? Thanks.


You hit it on the head. My 400 did the same thing, pulled the valley pan and had 2 flattened cam lobes and engine ticked, and was adjustable valve train. Ended up swapping motors as I had the spare motor-original, and engine in car was greasy and rusty.


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## wlbuckles (Apr 3, 2010)

Thanks for the info jetstang. No sense going thru all the hassle of putting in new lifters when at the same time I can put in a new strong cam. For no more than they cost, I'm gonna go all out and replace the push rods and rockers !!:agree


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## geeteeohguy (Feb 2, 2008)

Buckles....be sure to use a ZDDP additive to your engine oil. Lack of ZDDP is probably what waxed your cam.


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