Sorry to post this over here, but not much traffic on the V* Buick board. Any thoughts fellas?
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My 70 Skylark sits quite a bit, and I'm not sure when this problem first developed...but it's been some time ago.
Rebuilt 350, 11:1 comp, with headers.
I've got a tapping sound in the engine that is there at start up, and persists even if you have driven for an hour. The sound, of course, fluctuates with the RPMs.
I've had exhaust leaks before, on other cars, that sounded like a lifter tap. So the first thing I did was drop the passenfger side header and checked the gaskey. From the looks of the gasket it was likely leaking a bit on the back port. Changed the gasket and re torqued. The sound was still there, no change. i started the car at night and tried to look down around the flange for any sign of fire. Nothin'.
Sooooo, I figured it was probably a collapsed lifter, from the car sitting so much. I pulled the valve covers and applied pressure to the rocker arms with a hammer handle to see if I could affect the sound. Unfortunately, scorching hot oil shooting all over my arms cut that idea short.
I decided to go ahead and change out the lifters anyway, and while I had the intake off, I tried to get a good look at the cam lobes. Can't say that anything looked terribly worn. The lifters themselves had a small amount of contour to the bottoms, but they were consistent.
I did a good 25 minute breakin on the motor like I would with a fresh cam setup, and kept the RPMs up......and when al was said and done, I had the same damn tapping I've had all along.
What the heck is going on here?
First things first, is there a good, tried-and-true method of determining the source of the noise? I've listened to the motor with a stethescope, and can't really pinpoint the source that way either. But the more I listen to it, it does sound like a mechanical tapping.
Any help fellas? I'm getting frustrated.
...............................
My 70 Skylark sits quite a bit, and I'm not sure when this problem first developed...but it's been some time ago.
Rebuilt 350, 11:1 comp, with headers.
I've got a tapping sound in the engine that is there at start up, and persists even if you have driven for an hour. The sound, of course, fluctuates with the RPMs.
I've had exhaust leaks before, on other cars, that sounded like a lifter tap. So the first thing I did was drop the passenfger side header and checked the gaskey. From the looks of the gasket it was likely leaking a bit on the back port. Changed the gasket and re torqued. The sound was still there, no change. i started the car at night and tried to look down around the flange for any sign of fire. Nothin'.
Sooooo, I figured it was probably a collapsed lifter, from the car sitting so much. I pulled the valve covers and applied pressure to the rocker arms with a hammer handle to see if I could affect the sound. Unfortunately, scorching hot oil shooting all over my arms cut that idea short.
I decided to go ahead and change out the lifters anyway, and while I had the intake off, I tried to get a good look at the cam lobes. Can't say that anything looked terribly worn. The lifters themselves had a small amount of contour to the bottoms, but they were consistent.
I did a good 25 minute breakin on the motor like I would with a fresh cam setup, and kept the RPMs up......and when al was said and done, I had the same damn tapping I've had all along.
What the heck is going on here?
First things first, is there a good, tried-and-true method of determining the source of the noise? I've listened to the motor with a stethescope, and can't really pinpoint the source that way either. But the more I listen to it, it does sound like a mechanical tapping.
Any help fellas? I'm getting frustrated.
