Using spark plug gap wire gauges, I've measured the Comp promagnum clearance to the 1.56 valve retainer at .030 clearance when closed. I found some talk on the Chev boards about rocker clearance suggested to be .050 minimum, anyone disagree with that?
I sent Comp tech an email to see if there was any problem milling in an additional .020 clearance in the armpit of the rocker, but no reply. Anyone clearance these steel rockers before? I have verified my spring open pressures to be 370#'s @ 552 lift. I can vouch for the Proform on head spring
checker as well, it works well and is easy to use, good tool to add to the toolbox.

Why wouldn't 0.030 of clearance work? Are you thinking the rocker arm is going to deflect enough that the bottom of the rocker arm will hit the retainer hard enough to cause an issue? I doubt that will be a problem and I wouldn't machine on the rocker arm to add clearance. If you think the rocker arms are weak then it doesn't make sense to weaken them more.

I don't know how much give there is in a retainer, and gyration in the valve stem without doing something like spintron video testing to find out. The only number I can find on the web is .050, but I am looking for some real work experience since I don't have the testing equipment to say that .030 would be ok or not, and I rather not run it to find out it's not.
I would have to do a clean long shave probably with a large end mill to avoid a sharp edges, .020 isn't much. From reading, it sounds like cutting clearance into the aluminum rockers is a normal thing, but can't find much at all on the B engine promagnums usage on the web.
I could put a lash cap on the valve, but my rocker tip scrub pattern is centered right now.

You may want try checking the profiles of some other brand lightweight steel retainers. They sometimes are dimensionally smaller than standard or titanium retainers which could give you the small amount that you are looking for without putting a second question into the equation about strength reduction incurred by machining the rockers.I personally used Isky lightweight steel retainers for my Victor head/ Hughes rocker combo for a solid roller cam.I was able to fit 1.625" valve springs here, but only after using Mike's (B3) rocker geometry kit. Another member here,Jeremiah, suggested that I look into Isky's inventory my valvetrain that was similar to his.Others here have rightly pointed out how lacking the original Mopar shaft rocker geometry is. As stated before, Mike at B3 racing is a phenomenal source on this information. Remember, .005" is as good as .050" here if the components remain dimensionally stable.Valve stem scrub, in my opinion, can be overly adressed in an engine that is not highly modified,due to cost versus returns. It can get VERY expensive and time comsuming in a minor or medium build. Only you can decide how important it is in relation to the rest of your build. Good luck. Bill

I’d be fine with .030”.

I agree with fast68plymouth. True clearance is just that- clearance. Some times you don't get much in the bank, but at that clearance check each individual pairing. Check for witness marks after run to some RPM. Bill

I have a customer who is running Comp rockers on TF270 heads with no problem. He makes about 750 hp and runs high 9's in a Belvedere. Races every weekend and hasn't had any issues with the Comp rockers. Used them right out of the box with no modifications. Didn't need to do any tricks with shims or spacers or moving the shafts. Bolt together and run.

I'll go through them again and make sure its at minimum. 030 on each one. Never did hear from comp cams at all.
Out of the box fitment had some issues, the side clearance was tighter in some places than what comp specified. Also on some, the rocker bushing stickout was running against the aluminum rocker stand instead of the steel hold down retainers and I had to mill .015 off the rocker stand sides to get clearance and better the roller alignment with the valve. They look good out of the box until you really start looking.

I have a pump gas 440 blower motor to fix for a customer who does not know who made it or anything else about it. It had a steel core solid roller cam with Comp Cams 829 lifters and Comps early single shaft stainless steel rocker arms that they recommend in their catalog to not use more than 350 Lbs. max pressure on the valve springs. This cam had .345 lobe lift so it had less than .500 valvelift with the lash
I call Comp Cams 3 weeks ago and ask them if that pressure still applies and they said absolutely, do not exceed 400 lbs. under any use
I got the new Harland Sharp single shaft rockers this week and am now waiting on Manton to make my new pushrods for this motor
I'm hoping the customer will have me dyno test it also

do the rockers look like the pic above your post but more silver colored? are they unbushed? do you know the part number?

The ones that were on that motor are stainless steel color, not coated at all. I don't know what part number it was when sold
I was told by that rep during the conversation that their paired shaft stainless steel rockers will work good with a lot more spring pressure like I run on my bracket race motors,700+ Lbs. opened
These will end up being used on a small hydraulic lifter or solid flat tappet motor with under 400 Lbs. max

The Comp steel rockers for Mopars were never “stainless”.
They were/are 8620 Chromemoly.

The issues with the early ones and high spring loads was because the early ones weren’t bushed and could seize on the shaft.
They are now bushed, so that problem has been solved.

If someone has some of the early ones and you want to use them with higher spring loads, send them to RAU and have them bushed, and have them supply the undersized shafts, spacers, hold downs, etc.
That’s a pretty nice set up.