Ok, so my O/T daily driver got totaled, so the money went into making my next closest ride ridable. Here is what I have got. 1953 ford f100. 351w fmx out of a 71 torino. The motor was built my the machine shop, my mechanic friend and myself about 5K miles ago. My friend was in charge of specs, to which he bought a 268/512 lift cam and a few other little things about the truck made it too dangerous to drive, so I parked it for a few years. So here is the thing. I bought an edelbrock performer cam to match the intake and carb. I installed it about a hundred miles ago, however when the heads were at the machine shop, the guy instead of changing the seats in the heads, he put oversized valves in it. 2.02 what I was told, and heavier springs. Now when I put the new cam in, I put new lifters and new timing set. I started it up and it ran real smooth for a short time, and pulled 17hg on the vacuum gauge. After a while it started to get alittle less smooth and act kind of fluttery under a load. I also notice a ticking sound like the lifters are collapsing. Im running 15w-40 and I also notice that when its colder and I first start it, it seems to be better than when it gets warmed up and have been driven a few miles. It gets worse as it gets warmer. So here is the question. I have new springs (NOW) that are supposed to be matched to the cam and new pushrods. I have a feeling that I am going to have to replace the lifters too because of the ticking, but I am wondering if all of this is because I didnt change the springs, or if I change the springs will it straighten out, or were they just bad lifters to start with? Anyway, I plan on changing the springs and pushrods and see what happens, but deep down I think I will have to swap out lifters too because of the ticking and fluttering, but I am hoping that changing the springs will settle the rest. Anyone out there that works on engines for a living have any experienced input on the subject please chime in with words of advice and explanation to go with guidance. thanks.