My block is done in four sections with Moroso epoxy. Three smaller, rectangular pieces cover the openings over the cam and on larger "T" shaped piece protects covers the opening in the front near the tower shaft bushing.

I was mostly mitigating the cam or oil pump drive from accidentally digesting a 7/16" pushrod and not too concerned with a small mesh size due to bushed roller lifters and non-needle bearing rockers. It would make sense to use a mesh smaller than your smallest part.

For a supplier check ebay. There was a guy selling smaller sections of stainless in any mesh size you can think much cheaper than the typical industrial supply shops.

Putting mesh above the roller wheels won't stop the needles from falling out the bottom of the lifter bores, will it I had two Mopar brand solid roller wheels break in half and get the cam, luckily I shut the motor off before sucking any of the needles bearing up into the oil pump

I used aluminum window screen on my X block. There were enough holes and area that I was not concerned about the small mesh. I even build a dam for the rear of the block and screened a couple holes in it to give additional exit space. I did all this after a lifter came apart and thankfully no major damage was done. I used JB Weld to glue the screen to the block. Has worked great.

I have a basic concept of securing the screen without screws or epoxy. I'll make a drawing and post it here. With the various blocks (e.g. factory, megablock, KB, and etc.) there are differences in the shape geometry around the drain holes though.

Why bother with valley screens?
Put a hydraulic filter strainer on the suction line in the pan and all your issues are solved.
Ran my milodon pump that way for 10yrs and the pump was like new inside.

you would not believe the amount of damage something like a broken lashcap can do to an engine if you're also running a windage tray. they chip away at your rods leaving potential stress points for a crack to develop into a break. Also broken rocker arms falling into the oil return holes tend to break cams & that in turn does other damage. Valley screens are worthwhile if you're a regular racer.

Thanks id appreciate it, i fabbed up a hold down today like what rebel posted the pics of and received some screen today but haven't started any block mods but im hoping to get the block in this week or next for final machining so I'm trying to dot all my eyes and cross my teessss.

^^ Love you car man..

Wont stop the needle bearings, but the screens are a good idea.

Greg has had issues with rocker arm failures and is focused on keeping broken rocker parts contained.

I've never broke a rocker that the needle bearings
came out(knock on wood) but have had lash caps and
broken PRs laying in the valley.. I dont want that
trash getting hung up on a cam or have it fall down
onto the crank/rods at 8000+ rpm.. that screen has
done its job for me a FEW times... the lifters are
below the screen so it might not help with them
but it does help for stuff up in the heads

Afterr reading Cab's comment about the roller lifters, though I haven't lost any, I may opt for a finer screen in the pan to go over the one that is there. That one though will need to be sized as big as possible and still stop the needles. Anybody know what size roller lifter bearing needles are?

Greg.. myself I wouldnt do that.. if you make that small
enough to stop anything that could get there I dont think
you would get the flow you would need.. specially on cold
oil... JMO.. at some point you just have to take your chances
and hope it doesnt happen

On my roller lifter failure it was the upper part of the lifter that failed and left the 2 lifters untied. Even tho small parts got down in the rotating assembly I was fortunate enough to discover the problem before either lifter turned so the damage was not nearly as bad as it could have been. I will not run another without some fine screen to keep the parts on top.

I should have clarified in my first post that screens are a good deal Not intending to keep anyone from using it, sorry I've had lash caps and psuhrods drop down into the lifter valley when a valve spring broke

Why not use a bushed roller lifter? Safer & a lot stronger. Personally I don't trust needle bearings at any level
https://www.lunatipower.com/News.aspx?id=121

When I bought all my stuff they didnt make the bushed lifters..
if I were buying something now I MIGHT look at them.. but
as I said already.. I have never had a needle bearing come
apart on me.. been using them for years now

Thanks DARTH if that thumbs up was for my bucket of bolts...

Heres what i came up with using the design rebel posted and I ended up using a 1/4 20 bolts, I had to take it slow drilling the first 1/4 inch making sure it was straight it could of blew out a side every easily as theres only a tad over a 1/4 inch of meat on the rib.

you did well. i used a 7/16 drill for a pilot hole first but you got it done. now loctite in a stud & you're ready for a nylock nut to seal the deal.