rocker shaft clearances

[GoMangoBoys]

We assembled the rocker shafts dry (without assembly lube) and checked clearances.  As I understand, I want 10-15 thousandths clearance between each pair of rockers and the hold-down blocks.  We have way less than that.  We tried loosening the bolts and sliding the end hold-down blocks outward to open up the clearances, but they do not move enough to give is proper clearance.  What is the correct solution for this situation?  Do I open up the holes in the hold-down blocks so that they slide apart more?  Do we machine the hold-down blocks to make them shorter?  These are from Mancini Racing.  This is my first Mopar build, so the rocker shafts are new to me.  The engines that I have previously built did not use them.
Thanks

[usraptor]

Did you use any shims?  Try this watching this video.  https://www.youtube.com/watch?v=F7H5589tsLw  If you still are experiencing tighter than 10 thousands clearances I'd contact Mancini tech support.

[Scooter]

 

[GoMangoBoys]

I used what was in the package from Mancini.  Thick spacer between rockers, and thin spacers between each rocker and the adjacent clamp block.

[usraptor]

Try replacing the thick spacer with one of the thin ones or two thin ones together.  The most important thing is that the roller tips rides directly on top of the valve and not off to the side as shown in the video.  Every application is different and they provide you with a variety of shims of different thicknesses even though you won't use most of them.

[MoparLeo]

If you are using a Mancini part, what do they say ?? They have a dog in the fight, nobody here does.

[Chryco Psycho]

I agree start swapping shims , make sure the tip of the rocker is centered over the valve & gain clearance with more thinner shims used .

[GoMangoBoys]

There are 2 sizes of spacers with the kit, the wide ones that go between the rockers in each pair, and the thin ones that go next to each clamp block.  Those ALL measure about 47.5 thousandths.  I spoke to Manicini Racing and they suggested that I needed to replace the 47.5 spacers with thinner shims, so I bought a bunch of 0.15" shims.

[GoMangoBoys]

So I swapped out some of the 0.0475 spacers.  In each location where I removed a 0.0475 spacer, I added 2 0.015 spacers.  This effectively swapped a 47.5 thou for a 30 thou spacer.  I did this once for each rocker pair.  This gained me 17.5 thou for each rocker pair.  I now have approx 20 thousandths clearance for each rocker pair.  I saw a video youtube video that said 10-15 thou clearance, but Mancini told me 20 thousandths.  Does this seem reasonable?  See the attached pic.  This measurement is dry with no assembly lube yet.