i had to strip my new engine down to remove the trash from a roller lifter failure, was very surprised to find the exhaust valves were all white. I'm surprised because our plugs looked like we were running rich, but i thought white exhaust valves would indicate lean. this engine is running 98 octane unleaded on a 10.8:1 compression. i'm a bit confused, anybody got any input into this?

Ahh...interesting...I say this becuase I had exactly the same experience as I tore down the top-end of my 360 motor for a little refresh.

Here is the matching forum post link of mine, includes photos as well => Original Post

I do not think there was a consensus regarding the cause though.

Off topic but why are you running 98 octane unleaded on a 10.8:1 compression? Did you every try a lower octane fuel? It may go faster

As long as you don't have one hole that is way different, looks good to me. Burning nice and clean.

From his location in NZ I'm assuming that's 98 MON (as in Europe). We use AKI = (RON+MON)/2 and RON's about 10 points lower, so his 98 is our pump 93.

Didn't know that, thanks. My 11.2 comp loved 93.

That white is additives in the fuel... you must
be buying pump fuel... race fuel doesnt put a
lot of stuff in it

right, thanks for your input guys. yes i'm down under so our fuel probably is rated differently & yes it is pumpgas. so good to know its all good-ish. my Racecar Dart uses leaded fuel & it don't look anything like this but this motor has a fuel line unit that adds tin into the mix to make up for no lead in the fuel. this could be a contributor for the white i guess.

You are rich, that white stuff is ash of the black stuff everywhere else...exhaust valves run hotter, so on them the black is white.

What he said, especially on a pump gas deal..