Can a Comp Cams '67 & down / '66-'71 Hemi lifter be used in a '68 & up big block? I know the lifter is a slightly different length & the pushrods should match. Visually the difference appears to be the oil ring on the outside of the lifter. What are the advantages/drawbacks of the wider gap of the earlier lifter vs the newer, narrower oil ring gap.

I have the early style & I am putting together a '68 block. I assume the oil galley holes are the same.

The listing in Comp is incorrect with regards to the hemi....... At least gen 2 hemis.

The functional difference in the early/late lifters is the diameter and depth of the pushrod seat.

The early pushrods have the end that "plugs into" the pushrod seat necked down to 1/4".

The late pushrods are straight 5/16".

The early pushrods are also about 1/16" longer.

You just need to use the pushrods and lifters that match each other.
Early with early, late with late.
The year of the block makes no difference.

Where you can have an issue is if you try and run adjustable rockers with early lifters.
You would have to have pushrods made that had the necked down 1/4" end on the bottom, and you would need a correct early style checking tool(which afaik doesn't exist).

If you want to run adjustable rockers, the best bet is to switch to the later lifters so you can use "normal" pushrods, checking tools, etc.

Generally, in today's performance BB Mopar world....... The early style pushrods and lifters would be considered the "oddball" parts.
Using the later style parts is a better option IMO.

The Comp 822-16 is what I refer to as the "universal .904" hyd lifter, and IMO is not really "correct" for a BB Mopar. It is the same as a Johnson A-2011, which is really a SB/AMC lifter with pushrod oiling.
Many parts suppliers have used that lifter for most Mopar v8's for decades.

I generally prefer to use the A-976, which is used in BB Mopars only.

The Comp 824-16 is an A-812, which is the std Mopar v8 hyd lifter used from 53-67.

The oil band on the 976 and 812 is the same....... A thin band near the top of the lifter.
The only real difference between the two is the pushrod seat.

Comp doesn't offer the A-976 lifter in their line up.

In some installations the wider gap will become exposed at maximum/minimum lift and create an oil pressure leak.

I believe Comp Cams assumes that the user will choose the correct pushrod length and ball end to match the lifter.

Pulled the Comp 824 lifter & it doesn't actually have the wide oil ring as the pictures on the website shows & what the tech on the phone said.

So at this point I'm not sure if the only difference between the standard lifter & the 824 is the actual height to accommodate for the longer push rods or if it actually is designed for the smaller push rod tip.