1968 Camaro with small block 350 just rebuilt. I had the engine rebuilder installed a Holley Mechanical fuel pump. Drove the car home and I hear knocking at higher rpms. Rebuilder says it's the fuel pump so I go out and buy another one and replace it myself. Still a knock. Are these fuel pumps inherintly noisy or could it be something else? Anything to do with putting in a hotter cam? Perhaps the pump rod is too long now?

Are you sure that the fuel pump pushrod material and the camshaft material are compatible (since the engine was freshly rebuilt)?? If it really is the pushrod (you may want to use a technician's stethescope to help you) it may be that the fuel pump ecentric on the cam is getting wiped out. Did you inspect the pushrod when you re-did the pump?? Does it have hardened ends on it??

The rod looked fine. What do you mean by hardened ends? Why wouldn't the materials be compatible?

One style of pushrod is for hydraulic and mechanical "cast" type camshafts. Both ends of this pushrod are hardened steel tipped for best wear characteristics in quality for stock engine rebuilds.

Another style is specifically for use with 8620 and 9310 steel billet roller and slot hardfaced camshafts. One end of the pushrod has a bronze tip to compatibly bear against the fuel pump eccentric on the camshaft, eliminating the wear problems that can occur when using a standard fuel pump pushrod (especially in endurance or street type applications).

I just went thru something like this few weeks back but it may not be your issue. I was running a 110 gph stock style Carter 6900 pump,, still has the stock 5-7 psi . I noticed my brass tip push CC push rod was worn,,, It was noticable when comparing against the stock steel ... Stock is 5.750. You should not need a special rod unless your are running the roller cams or hi pressure 6-9 psi pumps, as I have been told. So I pulled the Carter and went to the Holley 327-11 and am monitoring.



If you are hearing a click at hi speed and suspect the push rod. Pull it to check and check to see if the pump lever is worn or damaged. Someone on this site ran into this,, might do a search on the subject. Take a piece of garden hose about 3 or 4 ft long and put your ear to one end and the other to the suspected part or area,, you should be able to hear it,, just like a stethsope.

Another possibility and in my case ,,, you COULD SUSPECT fuel pump cam lobe wear but I serioulsly doubt it on a cast flat or hyd shaft. I have never heard of it. But never know, you could be the first person in the world to have it.

Good advice...