The problem explained on another mopar site is not necessarily to do with the hyd. roller lifters, its the stock blocks themselves. This is a just 1 post by challenger340.... PRH took part in this thread, most of you know all this anyway but it may be useful info for others>


The problem many face when using Hydraulic Rollers in BB Mopars, an Engine never designed or envisioned to use them, is the very short distance between where the very large Oil Gallery intersects the lifter Bore, and the bottom of the Bore itself, which is also the exact spot where maximum Lifter Bore wear occurs in old Blocks, allowing excessive lifeblood Oil Pressure leakage out, rather than into the Lifter maintaining preload.

Add to the above,
that Hydraulic Roller Cams require higher V/Spring Pressures to keep up with the increased ramp Roller Lobes, and you have a situation where lifeblood Oil Pressure to maintain Lifter preload and valvetrain stability is fighting against the worn Bores and higher Spring pressure trying to keep it out ..... clackity.... clackity... clackity.... or very poor rpm capability.

Interesting to note here:
is that when CRANE was initially doing the R & D for Hydraulic Rollers with FORD back in the early 80's.... one of the first identified Block design changes was to Lengthen the Lifter Bore castings themselves to assist in Lifter sealing.... hence the Mid-80's Ford "HR" smallblocks with the taller(longer) lifter Bores.
The same was done over at GM etc., as they were updating castings to run HR's... they all lengthened the Lifter Bores in the HR Blocks for this reason.

The best answer for trying to run HR Lifters in these old BB Mopar Blocks with the Short & usually normally Lifter Bore bottoms.... seems to be one of 2 things:
1.) Bush the Lifter Bores to control leakage, an extremely expensive proposition
or,
2.) Run the HR Lifter basically bottomed out for adjustment, with only about .010" or so plunger preload remaining.... so basically running as a Solid.

#2 is now the prescribed "FIX" at pretty much all Cam Manu's for BB Mopar's when you phone to complain as many do.... of "noisey valvetrain"
and,
begging the question, if so many are having to run the HR Lifter Plungers in BB Mopars down .080", .090", even .105" to shut them up, basically "Bottomed" with 3 & 4 Adjuster Threads hanging out the bottom of the Rockers, why not just run a tight lash Solid "Street" Roller Cam instead ? with even more power/Trq than the HR ?

Anybody with a dis-assembled Block ?
Take a flashlight and go LOOK at the bottom of the Lifter Bores and the distance between where the Oil gallery intersects it to out the bottom.... see what I am referring to here, even better put a Bore gauge in their for yourself if you have access to one.

Link to full thread
www.dodgecharger.com/forum/index.php?topic=128846.0;all