Push Rod Length

[The Real McCoy]

I'm putting a 428 together with a Comp 280H cam and new Comp lifters.  I was hoping to reuse the original 9.59" push rods  and non-adjustable rocker arms.  During the engine assembly I checked the length of the push rod with an adjustable push rod.   The push rod was extended to 0 lash which  measured up at 9.497, adding .030 (+ or - .010) per the recommendations that come with the cam the push rod should be 9.527.  This would put my original push rods about .060 over Comp Cams recommendation.

The lifter's piston travel seems to be close to .200 so I am wondering if I really need to change push rods. It would seem that the 9.59 push rod would come close to centering the lifter piston.  So, looking for some feed back on this subject so I do the right thing and avoid spending more $$ unless I really need to do it.

[Hemi Joel]

One of the tricks that pure Stock drag racers who have to run a hydraulic cam use is to almost bottom out the lifter, so it acts like a solid. They don't seem to have any problem with it, so I think you will be fine using the push rods that you have. Good luck!

[chris_r]

You are good run the 9.59 push rods

[The Real McCoy]

Thanks for the reply Hemi Joel and Chris.  Looks like I will probably stick with my original push rods.

So what is the background on the .030 preload recommendation from Comp Cam?  It would seem to place the lifter piston all the way to the top which probably would limit travel if they pumped up to far.  That might not be a bad thing if this happened to keep the valves from hitting the pistons.  I did compare the Comp Cam lifters to the original Cobra Jet lifters and they seem really close dimensionally and piston travel is also very similar so it  would seem the original lifters would have the piston at about the mid point and way more than .030 preload.  Just curios and trying understand there recommendations, and trying not to make a mistake that can come back to haunt me.