Thanks for the feedback. I wondered what the 0.050” would do as well….. so I just ordered one of those. First time doing this work. Learning the hard way. Will test that out when it comes in.

Don't get all caught up with the witness mark needing to be perfectly centered on the valve. It is more important that the witness mark be as narrow as possible so that you get maximum valve lift. There are people that will tell you that being off center will wear the valve guide, but they are wrong. It is physically impossible to push a valve stem sideways with a roller rocker.

Good point, any 'sweep' over the stem is rocker movement that does not translate to valve lift.

Getting a narrow sweep is priority, but getting it close to center should be pri 2. Running too far off center increases rocker to stem pressure with less contact.

Thanks guys. That all makes sense. Will post up pics when I test with the 0.050 and whatever works the best. Maybe next week.

Update: So these promaxx heads needs some more work, ie longer rocker studs.

So I got a couple lengths of those, and then also got the 0.090” and the 0.050” backset rockers.

In conclusion, on my exhaust valve a longer stud and a 0.050” backset on gave a great, repeatable pattern that is fairly close to center. Estimated witness mark width is 5/128”. On my intake, the 0.090” backset gave a great repeatable again fairly close to center pattern. Estimated width is 7/128”.

Exhaust

Intake


Thank you to everyone for their input to get this near perfect!

That is as good as it will ever get.

Great work. Thank you for getting a good detailed solution and photos.

Thanks guys! First time playing with engine stuff this much inside the engine. I learned a lot going through the motions here. Sure took a lot longer than planned. Now getting ready for number 2 engine. Should go much faster knowing I need longer rocker studs out of the gate and then knowing the offset rockers.