Hi Guys, I have just installed my 1968 430, which is bored .30 over and running a very mild cam. I have broke two fuel pump arms in less than 200 miles. Any suggestions? Thanks!
Do the fuel pump arms have that little plate riveted to them where it meets the eccentric? If so, I'd review what cam you put in there & see if the eccentric is at original specs.
I bought a fuel pump from Auto Zone, and it was Chinese junk, no plate, that one broke first, then I found an old school AC/Delco with the plate, a lot better built, and that one broke also. I will try to get some pics posted this afternoon, I have not pulled the AC pump out yet. I really appreciate you guys helping me out, thanks! Like I said before, the cam is not really super aggressive, so I a little shocked that it is having that much effect? I thought maybe I was installing the pump incorrectly somehow? It can really only go in there one way, right? I guess I could run an electric, but I really don't want to if I can get the mechanical figured out?
If you want the easiest way to install the pump, rotate the engine to TDC #1 firing. The pump will slip right in and the pump flange will be flush, just put the bolts in. If you put the pump in when the eccentric is in the wrong position, you end up fighting the pump spring while trying to bolt it up. That can lead to stripped threads in the timing cover. I don't think it is possible to put the arm on the wrong side of the eccentric, I don't think the pump would go on. That's the only way I could think the arm would bend or break. So there is a correct way to install it.
If the pump & cam are stock, was the timing cover ever changed out? If so, beware...especially if it was one of those Pro-Form Chinese knock-off copy covers. Those have been known to be made from inferior materials and have incorrect dimensions & tolerances, which could cause issues in the position/placement of components housed within or on the cover...like the fuel pump.
Hey Guys. First I wold like to thank you guys for all your great advice. This is my first Buick, so I am learning a lot, I really LOVE the car! As it turns out, after pulling the timing cover, I discovered that the heads of the timing gear bolts were scared up? I did a little research and discovered that my engine builder did not install original Buick 430 timing gear bolts. They have a very flat and thinner head on them, wich gives the clearance for the fuel pump arm. So moral of the story, when replacing your Buick timing gear, always use the original style Buick thin head timing gear bolts!!
Pardon me for asking: but how did you not hear those bolt heads hitting the fuel pump arm? Seems like that would make one hell of a racket. If the builder gave your engine back with that kind of a clearance issue, I'd be very wary of what else may go wrong.
Well that's what made the issue so difficult and tricky to diagnose, under cold start and idle conditions, the bolt heads where either clearing, or touching so lightly that they made absolutely no noise, it was only under heated and high "R" conditions that things would expand enough for the bolt heads to actually catch and break the fuel pump arm. I have full confidence in my motor and builder otherwise. The thing runs like a scalded dog, and sounds as solid as a brick. He has done a lot of work for me in the past, I always get a very dependable, great running motor back. This was his first 430, so I am going to let it slide (just this once). P.S. He offered to come and figure things out, and fix it for free, I just didn't feel like waiting 3 weeks.
