I have a 400 that I stroked to a 526. It has the Indy little ez 295 heads. I have the t&d rocker arms. My question is I have the external oil lines on the back of the heads and I drilled and taped the fitting to accept a Holley jet to control the oil. What size jet should I use?
Thanks
Brandon

Forgot to say that I have it so one jet is feeding both heads

What I would do until someone comes up with a definitive starting point is put a .0625" (1/16) jet in there for starters & preoil with the valve covers off & see what you see for quantity of oil end to end on the shafts

We have the -1 heads and use .060 jet . Gary

I use a .039 restrictor in each oil line on my motors with two oil lines with Harland Sharp true roller rocker arms with solid roller valve springs to help cool the springs If your rockers are not true roller bearings on the shafts then I would try it like you have it now and change it later, if needed
EDITED: Are your T&D single shaft or paired shaft rockers?
If yours are the paired shaft system you need pushrod oiling for them
If not, continue on

I has SR's with Harland Sharp rockers using a Milodon oiling system. I restricted until I had full oil pressure back. It ended up at .040" restriction in each line.

They are single shaft rockers. They are roller bearings on the shaft. If I am going to use one jet to feed both sides should I start with like a .060 restricter? It is a hydraulic roller. The reason I am asking is I don't have a lot of oil pressure when warmed up at idle. It only has like 25lbs. Once I hit the throttle it goes right up. I was just wondering if I was loosing too much out the rockers.

Thanks
Brandon

060 between both heads ain't excessive. 25 at idle is OK as long as it jumps up immediately (& it does) so you are fine & I think 060 is in the ballpark but I would visual for how much quantity you see

I would warm it up, go drive it to get the oil warm and then pull a valve cover and start it up to see how much oil your passing threw the rocker arms and go from there
If it is to much in your opinion restrict it smaller, if it is okay in your opinion leave it alone and the same thing if you think it is to little make it bigger
I had .39 restrictor in each line to my SR heads in my old pump gas Duster, it had 18 to 20 lbs. at 850 RPM with 5W20Wt oil at 170+ F oil temps, it had over 30 Lbs. at 1200 RPM and 65 Lbs. above 2500 RPM
I like and use the old formula of at least 10 Lbs. per 1000 RPM with hot oil, 10 Lbs. at 1000 RPM and 70 Lbs. at 7000 RPM

.039 diameter x2 = .055 diameter (single feed)

Yes, you are bleeding down. Might not be an issue, But I don't like much bleeding if I can help it. 060" restrictor sounds like a good starting point.