I just finished reassembly of my LT1 with redone heads. I checked the push rod length with the Comp Cams cheepo plastic thingy and it showed that my pushrods were about .030" short. I went ahead and finished the assembly with zero lash plus 1/4 turn and fired the motor to look at the contact pattern on the valve tip and sure enough the patern was slightly "centered" toward the header side of the head. I then re adjusted the valves down to zero lash + 3/4 turn and the pattern moved back closer to the center of the valve tip.

What's a reasonable allowable error in pushrod length. My gut feel was that .030" wasn't going to be a problem.

Steve

 

My personal feeling is that you'll be OK. On a hydraulic I like to leave them a smidge long because when you lash them and the hydraulic lifter pluger gets pushed down a little it effectively makes them even shorter.

If you're a little squeemish about this maybe go .050" longer which will leave you .020" too long, and then when you lash you'll be right around perfect.

I also use that same cheap plastic push-on tool to get me within the range of "sanity" and then fine tune by looking at the sweep across the valve tip.