427basketcase

Hi, I have been helping out my friend who recently purchased a 1971 coupe, it's a number matching LS5 4 speed that has been sitting about 22 years. He was told ny the seller that the engine had been rebuilt sometime in the 80's and everything looks to be so, but we can't seem to get rid of what we think is lifter noise (have adjusted 3 different times with 3 different methods). It's not a bad or obvious noise like ticking or clacking, but almost like a sewing machine noise. Not so much at idle either, just when reving.
I remember hearing about BB fuel pumps making this noise and mimicking lifters.
Anybody have any experience with this? Should we replace the pump and see if the noise goes away?

GDaina

no, mechanical pumps don't make noise...check for an exhaust leak...

morganjd

Take the fuel pump off and make sure the fuel pump rod is not sticking. If it falls right out, then it is not the shaft. It could still be that the pump arm is weak and not keeping the lash out of the pump and cam. I have first hand experience in this situation

gve

I had the same problem with a new pump on a big block I returned the pump and got a new pump and rod which was slightly longer then the one that was in it. It solved the ticking noise.