See videos... Now the funny part is a quick check with a machinists ruler shows installed height being the same across the board, may be pulling heads tonight... Just to check properly...

Complete BS again to have to deal with this on a simple 540 build that others seem to get hundreds of hours out of...bob will hear from me if in fact I prove my seats are sinking... If that's the issue

https://m.youtube.com/watch?v=G8KCWw137rM

https://m.youtube.com/watch?v=JIV_AcI25HY

Tim, if sinking seats is a common problem with new aluminum heads, did bob tell you that you'll need to pull the heads at 65 hours for a freshen up?

What do the oems do , as their assembly line alum heads go 250k miles.

What is mercury marine doing on their 525, 600, 700, etc, that have aluminum heads that go several hundred hours before needing attention.

Its the valvetrain. This is why millions of dollars get spent on durability testing, to prevent issues.

I know of many engines, with brand new aluminum heads, that had mild crane hyd roller grinds, that did not have sunken valve seats after 65 hours .

Actually we've seen the same thing using 525 cams in builds with new aftermarket heads. Some of the stock 525's we did over last winter/ summer had some of the worst seats in them than anything motors didn't even have 100 hr's on them. Most of the hours on them were at idle... Unless someone swapped the ecm's and the hours were not accurate. But it seemed to be a trend. The 525's don't have nearly enough valve spring on them.

From one vid, looks like you are putting strightedge flat across one valve tip. The BBC valves are canted like 4* or close to it. That will make the strightedge at an angle too, so one side of straightedge will be lower than the other.

Layed across all 4, now that being said I can't get it directly on the valve tips due to them being lower then retainer, but they should still all be the same... Trust me I hope I'm wrong... But seems there is some sort of issue to look into...intakes are all fine also

Tim, are these the same set of heads that originally had the heavier springs in them? But I know you had them all gone through after you found that Right, IDK Ihave used the same seats in my Alluminum heads for a very long time (16 years), no issues, never sunk, but I'm running very mild Harold Brookshire cams! I do cyl head checks (send them to my cyl head guy) every 3 years just for piece of mind, dont want stuff coming apart for the lack of checking. In your case I hope your machinist can pin it down and correct it. that's no fun!

I am pretty sure I'm going to pull the heads tonight myself and go over things with the proper tooling

Hey Tim you should change out them cams before they cause damage
- everyone (except bob lovers) 2015

Lolol then there's Dan... Haha