Dist drive noise

A

acenewman

Member
Have an engine noise I am trying to track down. Light tapping noise at idle which seems the loudest in the chain case when I listen with a stethoscope. Thought it was valve noise so I relashed with no change. Last night I figured out I had 0.012 inch of end play in the dist. Pulled it and added a fiber washer and got it back to zero lash. Reinstalled and still no change. I have tried adjusting the dist hold down and even running the engine with it loose with no change. So my question is has anyone run into noise caused by the dist drive or the oil pump? Really seem like it originates in the center of the motor around the dist. Primarily heard at idle. Doesn't seem to get any louder with increased engine speed. Eng is freshly rebuilt and has about 30 miles on it. Other than the noise it runs nice and strong. Appreciate any insight, Chris
 
Have you checked the cam plunger in the timing gear cover, the cam may
be moving back and forth.

Bob
 
How much clearance is there between the cam and the cam bearing bore?? ---when measuring blocks I have found that it wears more than the other cam bearings ---it is also the only bearing with pressure (and it gets first chance at any dirt the pump picks up) --it can make a knock as the cam lobes near it go from loaded to unloaded, also lifters loose in their bores can make noises
 
Don't know the exact numbers. I asked Hart Machine to check the clearance and bush the cam bearings if needed. There feedback was that it was in spec. They did the block prep and reground the cam. I checked virtually every other bit of there machine work and it was all spot on. But I guess you never know. Probably no way to check now that the engine is together?
 
Actually I only hear it when I am standing next to the engine with the hood open. Dont really notice so much when driving the car.
 
I suggest you run it for a couple hundred miles and monitor the sound. If the oil pump drive gear is new and you have a freshly rebuilt oil pump, there may be excessive pressure on the camshaft plunger and spring. This pressure may be causing the camshaft to "walk". When the camshaft walks and then returns to proper position there is a slight knock. If this the case, a few hundred miles of wear-in may solve the problem. If the center journal of the camshaft has excessive clearance to the block bore, it most likely, will get louder with time. Either condition will not hurt the engine to run it for a while. Good Luck!
 
Check the fit of the shaft to the driver unit, and to the short shaft. You want snug, but not stiff. Grease at each joint also. Bob
 
acenewman said:
Have an engine noise I am trying to track down. Light tapping noise at idle which seems the loudest in the chain case when I listen with a stethoscope. . . Appreciate any insight, Chris
Click to expand...

I suggest you take the cover off that "chain case". You may be suprised by what you find. :rolleyes: While you're in there, replace the thrust plunger and spring.
 
the dist, cam drive, and oil pump were all rebuilt. As I recall they all fit together pretty nice. Not overly stiff. The spring and plunger on the timing cover are both new as well. For clarity when I said "chain case" what I meant was the valve camber. Not sure why I was thinking "chain case"? Think I will take "Dave in MN" sugestion and drive and monitor for a spell.
 
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