I had driven the 330 to get gas the last time it was out. Parked it for a few weeks, went to restart and heard some not so good noises!

Apparently the valve seats fell out because the keepers, stems and locks were still in place and looked fine.

I can't be too disappointed because it's been together for for 10 years, 10,000 miles, hundreds of passes, ran 9's and was stone reliable as a driver up to this point.

Pretty sure the bottom end and block is fine but I'm going to put pistons, rings and bearings in while it's apart.

one seat or both seats in the same chamber ? What head?

Both seats.

440 Source Stealth.

If the heads get torn down and inspected, I’d be interested in a report on the valve guide wear situation………since you have 10,000 miles of HR use/wear and tear.
It would make for good reference data.

Back in 2017 I did a engine freshen up cause of a cam going flat, had about 5k miles on it, took the heads apart to do some better port work than I had done before, ALL the guides were toast, the 440 source valves that I had have machining lines like a record down the stems, NOT a smooth polished finish, not sure if that caused the wear or not, I replaced the guides & valves with ones for edelbrock heads in my Stealth heads.

Good and fortunate catch. My 511 had an intake start to come out on the 7th dyno pull.

The next time it comes apart I'll swap in a set of -1's or tf270's.

Are your Stealths out of the box as far as guides/seats? I had to have the guides and seats replaced. Less than 600lb open spring psi so nothung radical there.

Do you know your spring psi values? I'd be interested to know.

We had the same thing happen to our 440-1 heads at Norwalk. Maybe a smaller chunk of seat as a bit less damage but pretty similar.

Do you think nitrous played a role in the damage? O’Neill porting can fix that head for you. They are the one I told you about in another post. They do a lot of head repair, mostly race stuff. Guys name is Karl. They are in Benton, just short drive from you.

Notchback guy

Hmmm...aluminum expands at a higher rate than steel/iron, so I'm wondering if the seat fit was tight enough, or if there's too much heat in the chamber at times.
That would seem to rule out a seat dropping during a cold start, as aluminum also contracts more than steel/iron, but I could be wrong, unless fatigue is playing a role ?
Never had that happen on Stealths or Eddys or Indys on the street/strip cars, or on the Battens on the racecar, which once or twice I'd had some detonation, which I caught & addressed.
Those heads had a couple hundred passes without issues, and are still working great on the car, which is probably 350-400 passes after last year.

I also have a set with about 4000 miles on them, been running them for 10 years now. Guides in mine are also shot, I don’t have oil consumption or smoking issues but I get about a tablespoon of oil puddled on the back of each valve sitting overnight.

Probably! 😆

I called him yesterday but found a deal last night…

Mine had new locks, springs and retainers before I got them. It’s been 10 years so don’t know the spring details.

I bet we could almost guess what he'll find....I mean never say never,buuuuuuut........

So, what are you saying ??

Agreed, What are you saying??

I'm pretty sure Todd is saying that he'd expect the guides to be totally worn out at that point

If someone has the heads bolted on and in service, they don’t really “know” how the guides are holding up(and neither does anyone else).
So I look at heads that have been run, and off the engine…….as an opportunity to look them over and gauge how various aspects of the heads in question are holding up.

I get that, I do the same, seeing BOTH intake & exhaust seats fall out leaves me scratching my head

I’ve got a two pair of marine heads here from the same boat. They’re mercruiser/Edelbrock heads.
Out of 32 guides……31 are totally wasted. 1 is fine.
I’ve done several sets of these thru the years, the guides are usually fine.
As it turns out, it appears the guides in these 4 heads had been replaced before, with guides that are made from a different material than the originals.

So, the originals got bad enough to where they were replaced, and now the replacements are shot too.

The odd thing to me is the one guide that’s still fine, while all the others are all really bad.

As for the OP’s head with both seats falling out……..
My best guess is…….one fell out, then the trauma to the head from stuff bouncing around coaxed the other seat to come out.

Then again, looks like both valves broke off. Who’s to say one of those breaking off didn’t happen first?

That is weird one good out of 16, when I was building sprint car & oval track engines I was having hell with guides wearing out very fast & would lose some power off the corner, SBC stuff, I started leaving the valve stem seals off the exh 1st to experiment & they never wore out, intakes still went away fast, so I left the intakes off as well, problem solved, puff a little smoke sometimes but who cares, ran great, BUT this is race car stuff not for street cars, BBM heads would have a bad oiling problem if done this way, SBC it works , maybe could use a small umbrella type seal so they get a little oil ?

I'm not even going to try to have this fixed.

I found a good deal on some Trickflow 240's I'll be picking up this weekend.

Stuff like this keeps me in 906s in my car. I just drive and drive and drive. Aluminum would be nice, but would be a constant worry as to what’s happening in there.

The seats in our 440-1 heads failed likely due to weak valve springs and/or a weak hydraulic roller lifter. My engine builder thinks the valve bounced on the seat and hammered it right out. It was a bummer because we were about to rebuild the engine after that weekend anyway.

I had plans on pulling it apart and doing a wellness check this Winter. I did the transmission last year. My eventual plan was a set of Trickfows, I just got forced into it a bit early!