push rod length

[pagilman]

Hi, need help. I was just putting my rockers on and bought a set of hollow moly rods on ebay. When I started to put it together I measured the hollow rods next to the stock ones and they are about, guessing .020 shorter than the stock ones. I called the local machine shop and they said it would be ok to use them. ( new rockers and hydraulic lifters). I got one side done and thought you guys with assembly experience could tell me what you think!!!!!!!!!before I go any further. Thanks for any input, Walt:read2:

 

[rumblefish360]

This is wide open to a slew of questions.

Was the block or heads milled and if so, how much?

What head gasket are you useing?

OE Hyd. Rockers or Mecanical ones?

On the cams base circle, the pushrod must depress the lifter a min. of .020 with the rocker gear on, set up if mechanical and of course, valves seated closed.

I am not to happy with .020 as a min. and would rather set it up to depress the lifter approx. .050 downward. That would put the set up right about where the factory set it up for.

The lifter has about .100 movement with the last .010 not really useable. That amount isn't what you can push it downwards with your hand, just the way it is supposed to operate.

 

[camd64]

I too like rumblefish usually put about .040 or .050 preload. get yourself a pushrod length checker as they are inexpensive and good insurance. depending on the above stated issues you could end up with not enough preload and have valvetrain noise. most cam companies like to you to be anywhere between .020 to .060 preload. also very important to check for geometry and make sure the tip of the rocker is centered on the tip of the valve stem correctly.