It's always funny to me how life plays little tricks on us. Checking to see if we are paying attention or just trying to "phone it in". Case in point, these pushrods. I remember popping the valve cover off and looking at the rocker arms. I noticed the adjustment screws were all the way out. So, I remember trying to see if there was any valve lash, and, on number one rocker, there was. On the firewall, someone had written in sharpie, .020 INT and .020 EX. I thought this was kinda cool but also took it to mean, someone had checked the clearance.
Since #1 did have some play, I just went on looking at other stuff, put the valve cover back on and got her to fire up and run "screaming demon". Just kind of back-burnnered the valve lash as I had much bigger problems like a leaking fuel cell and an upcoming race.
SO fast forward to now, after tearing into this motor to fix some of the issues that crept up on me. I button her back up and now mind you my method for removing and replacing the rocker shaft is to evenly loosen the four nuts that hold it down. Been doing it this way for thirty years and have never bent a rocker shaft. The idea is if you do not disturb the adjustment screws, when you torque it back down, it she have the same clearance. SHOULD
When I took the rocker shaft off and the pushrods out, I checked the lifters and noticed four of them where a bit "scuffed" so I replaced them. after assembling all the bits and pieces of the motor back together, I fitted a new Payden head gasket and torqued it down to 50ft/lbs. Next I put the pushrods back in and torqued down the rocker shaft. Filled her with oil, water in the radiator, fuel in the cell and tried to start her up.
She coughed snorted and blew fire out the carbs, Good thing Brenda wasn't out there for that. It was kinda cool looking but also a bit scary to see fire burning in a carb throat in the garage. So, I fought it for about the next three hours and played with the timing and idle adjustment, fuel pressure and did get her to sort of run but really really rough.
Enough for one weekend and it would be a week before I could get back to her. During the week I thought about it more and started to think more about those pushrods. I remember thinking they looked like stock rods. And I remembered how the adjustment screws were all the way out. I had a set of shortened pushrods, well I had seven because one got bent because a lifter stuck in the bore on a new rebuild I did years ago. That's another story. Anyway, I figured the number one valve had clearance, at least some, so I'd leave it in and replace the others with this set of seven.
Dropped them in, adjusted lash, which now I was able to do. and...
SHE FIRED RIGHT UP!!! Idles great, revs up nice and she is roaring again.
but what I don't understand is, the old pushrods didn't grow. How is it that this motor ever ran to begin with? Yes, I did replace the head gasket but it is a stock item. Best I can tell so was the one I took off. It can't be .050" thicker. There were no shims under the rocker pedestals. I never changed the rocker adjustment screws, Hell, I couldn't have even if I had wanted to because they were backed all the way out to begin with.
So I bought an adjustable pushrod and need to check the rocker geometry. Then, I will order a set os shorter pushrods.