New heads, lifter/rocker question

I'm installing my reworked GT40P heads on my 351 and want to make sure my valvetrain geometry is set correctly. I've read how to measure the preload (pushrod scribe method) and it all seems very straight forward.

I started with cylinder #1, installed the lifters (coated in oil but un-primed) and pushrods in the exact same way I took them out. I tightened down the rocker pedestals, but I noticed when I did that I could see my exhaust valve spring start to compress before the rocker was fully seated. I verified I was on the base circle and checked again, same thing, the valve started to open. I continued checking the preload and measured .050" on the intake and .090" on the exhaust. The exhaust lifter could be pushed down by hand and felt "spongy", whereas the intake lifter felt solid.

I'm going to soak all my lifters in oil overnight and recheck to see if they prime themselves.

- If some lifters are still able to depress by pushing with my thumb, are they bad? Am I ok to replace individual new lifters with my old cam?
- I'll need shims to raise the rocker and stop the valve from opening, correct?

Bri892001 wrote: I don't know a whole lot about this stuff, but your issue with the exhaust valve opening when you crank down on the rockers: I believe it has something to do with head potentially losing some height (thickness whatever you want to call it) when it is machined/planed. This effectively brings the rocker down closer to the block, and effectively makes the pushrod as if it is longer. I'm sure someone will weigh in and explain what your solutions are for this.

That's what I was thinking too, especially with reworked heads I knew I'd have top recheck the geometry. I just want to make sure sure I have the procedure correct.

TRBenj wrote: You're doing good so far. You should be aiming for .020-.060 preload. It's normal to need a shim kit (.030 and .060 shims) on a set of refurb'd heads. I wouldn't want to use more than .090" of shims to get preload in spec- any more and if get new pushrods. But it looks like you'll get there. The shim kit is $10.

Great thanks! kit is on its way