I have some Lucas 20w50 break in oil on the shelf.
Will be warm outside when fired up.
Making an order for bunch of stuff so adding oil is no problem.
Not looking to save a dollar and spends thousands.
Don't have the Cam Card handy but my old brain says it is.
Cam is new but older Engle( said they used Crane blanks back then)
Think it is 240-252@50 .560-570 lift Solid Flat Tappet
(KV2-KV3?) tight lash ground on 110
Comp Cams Solid lifters have been on.the shelf 25 plus years, I know some say New ones could be soft.
Comp-Cams 1.5 roller rockers

Used their 10W-30 with both a SFT Hughes & a HFT Engle BB, zero issues, both engines' valve springs over 400# on the nose.
I use their Hot Rod 10W-30 on a few cars. Ran it in the SB roller-cam racecar too.
20W-50 is kinda thick IMO on a fresh engine or normal bearing clearances.

Thanks for the reply.
My last build was normal,10w40 with Lucas Additive, the one before that was 30W straight weight high Zink racing.
I just looked at Lucas site and Summit Racing looks like I must have bought the 20w50 Lucas Brake In since it only comes in
20w, 30w straight and 5w20 and 20w50 flavors.
My guess is I did not want a straight weight as thin as 20 or 5w20 and passed on straight 30 as well to get a muli weight.
Seems like they would make / sell a 10w30, 10w40, 15w50

I use it as well.
Doug

Take a look at the attached 'Bearing Clearance & Oil Viscosity Recommendation' chart from Driven.

They appear to be pretty spot-on, and at least in my case with mains (360 crank) at 0.0033 clearance and rods at 0.0022 I am going to run 10W-40. Now these recommendations are applicable to regular use as opposed to break-in, however I would say the viscosity stays the same while the ZDDP content of your oil needs to be a tad higher to give the FT cam a better chance of breaking in correctly.

Since that 20w50 you have is a break-in oil already I would imagine the ZDDP is high enough, good to check though.

I would be a little worried that it may be too thick though, especially at start-up when you want oiling to happen as quickly as possible...so maybe mix it 50%:50% with something like 10w40?

I use Valvoline petroleum base oils 5W20wt to break in all my new motors with some zinc additives for flat tappet cams and VR1 10x30W racing oil on the race motors with solid roller cams

I used it and wiped cams twice, ( not in a row) they were Mopar cams so I blame it on the cams. Every Comp cam no problems. But I only use Brad Penn break in oil, then Valvoline VR1 racing oil 20-50. Never had an issue since and spoke to mr.six pack and thats what he uses.

The Lucas and Driven break in oils are the best break in oils if you also have a fresh set of rings to seat