Hydraulic lifter play

[cr_bobcat]

So let me start with explaining what's going through my brain. I think I'm going to end up having my new rocker arms before my machined head is ready to go. So I was contemplating swapping the rockers out of my existing head and run that way until I finish the new guy. This will also give me a chance to kind of "feel" the difference of a couple of the different upgrades.

My questions are:
1) Is this a worthwhile exercise?
2) How much play can hydraulic lifters live with wrt pushrod length?

I'm going with the assumption that my existing head is bone stock and that I have a 0.050" gasket. This would mean that I'm running 0.025" longer than a stock configuration. The new head is supposed to be milled 0.070" for compression.

3) Can I get away with stock length pushrods for both heads?

If I have to buy shorter rods for the new head, then I won't be installing the new rockers on the old head.

They haven't shipped yet but I've at least placed the order for the new 1.65 RAU rockers. I'm still waiting on confirmation from them that the parts are assembled and ready to ship, but that was supposed to happen this week.

Thoughts?

Cheers!

 

[CZLN6]

Howdy Bob:

Stock FoMoCo lifters have a range of about .250" or 1/4" of an inch. That means with stock rocker arms, both non and adjustable you will have a range of .125" + or -. So in either of your cases you should be within the adjustment limits. When installing be sure to run the engine through all rocker arms motion and watch the contact of the arm to the top of each valve for correct contact.

Yes, It would be worth the effort to try the new rockers on the old engine just because you can. Older lifters will have slightly more clearance due to parts wear. I have no first hand experience with 1.65:1 rockers but they should be like the stockers. Angles and wear patterns will be slightly different. Keep us posted on your progress.

Adios, David