I'm changing my unbushed-lifter-bore, stock RB block from a hydraulic roller to a mechanical roller valvetrain.

I am leaning towards running the Isky 3672RHEZX EZ-ROLL X Solid Bushing Roller Lifters with the .125" higher pushrod seats, so I can run shorter, more ridged pushrods.

I have learned that virtually all mechanical roller lifters slightly uncover the lifter bore on the cam side of the lifter bore on unbushed lifter bore blocks. How much depends on the individual casting and machining characteristics of a given block. I would have bushed it, but I don't really want to tear down the short block to do it now.

Is there anything I should know or need to consider before pulling the trigger on these lifters or on not running a bushed bore for the lifters?

Thanks, guys.

Those are really good lifters but I think you can also get them in solid body? MRL has some lifters available that he claims work fine in unbushed bores, might be worth a call to him.

Thanks. I was told that its the notch for the wheel that exposes the oil galley not the lifter body.

What kind of spring pressure??
I have had great luck with the comp 848 with under 700lbs over the nose.Also put restrictors in the PRs.

The wheel should be shrouded and might not expose the oil passage, but is lift dependent. What is your lobe lift?

The cam specifics have not been decided yet, but it's on the small side for a mechanical roller. It should come in at or just over .600 lift with a 1.6 to 1 rocker.

You could have it ground on a smaller base if needed.. you
have to watch both the base and full lift... I have come
real close(closer than I like on the base) on my SB stuff
so look at the cam and what you want for lift
EDIT
Also those holes going to the axle are large so
you will loose a lot of pressure with them...
you have to figure that hole times 16.. I wasnt
happy with the pressure loss on my SB

Thank you for the insight. I hadn't considered grinding the cam on a smaller base the reduce the overall installed height of the lifters. I'll ask the guy going through and setting up the heads and spec'ing the cam about that.

FWIW I am not oiling the rockers through the pushrods.

Weather you PR oil or not.. the hole going to the axle and
roller is always leaking.. if this is race only I would
forget the axle oiler hole... JMO... the axle oiler is
really more for low RPM like on the street... again JMO

You'll be fine with that low of lift w/o the small base circle.

I run the Iskys. Even though my lifter bores are bushed the roller feed hole falls approximately .040" below the bushing at base circle. I hurt one at 85 passes. Isky checked all 16 and repaired the faulty part at N/C. Haven't had any issue since.
Doug