Slant Six Forum
https://slantsix.org/forum/

Sunken exhaust valve seats
https://slantsix.org/forum/viewtopic.php?f=19&t=63278		 Page 1 of 1
Author:  GregCon [ Sat Feb 09, 2019 2:04 pm ]
Post subject:  Sunken exhaust valve seats
Just some pics for information.....

I pulled the valve cover off the 225 and laid a straight edge across the vale tips....and I knew there were gonna be issues.

So when I pulled the head I could see the face of the exhaust valve was actually a little below the combustion chamber surface.

Removed the valve and the seat is gone! It's hard to tell from the pic but the valve was pretty much smushing itself a new seat as time went on. The valve guides were also pretty sloppy. The valves themselves looks pretty good.

I don't know much about the history of this car but I can tell you it's a 132,000 mile engine, never been apart before, and spent all of its life as a daily driver in CA. I know there's a raging debate on hardened seats but for this head....either it gets new seats or the junk bin.

Attachments:
lr valve seat.jpg
lr valve seat.jpg [ 153.29 KiB | Viewed 3026 times ]
lr valve seat exhaust.jpg
lr valve seat exhaust.jpg [ 189.99 KiB | Viewed 3026 times ]
lr valve tips.jpg
lr valve tips.jpg [ 192.49 KiB | Viewed 3026 times ]
Author:  SlantSixDan [ Sat Feb 09, 2019 3:32 pm ]
Post subject:  Re: Sunken exhaust valve seats
There's not much of a debate. There are those who adhere to the mistaken belief that 2018 unleaded fuel is somehow differently unleaded than 1975 unleaded fuel, in a magical manner that makes it not allow the exhaust valve seats to recede. Or something. Because reasons. And stuff. There's a lotta math, you see. It's complicated.

And then there are those who understand the situation is as it always has been: a Slant-6 without hard seats will run on unleaded for a long time in light-duty service without a problem, but when it's time for a valve job, it's time for hard seat inserts.
Author:  GregCon [ Sat Feb 09, 2019 3:42 pm ]
Post subject:  Re: Sunken exhaust valve seats
What's weird about this engine (for me) is it's the first engine in almost 30 years I've rebuilt without changing to aluminum heads....all of which came with hardened seats anyway. In this case, there is no aluminum head available so....

I'd consider this car light duty, even, so here's proof that you won't get away without hard seats if you actually drive the car. I'd guess the car was burning unleaded gas for all but the first 10 years of life. On the other hand, for cars that see 500 miles a year I guess the issue might never crop up.

So this car woulda been running fine with its slightly ticking valvetrain then slowly started running even quieter....and then it started running weaker and weaker. The mechanic woulda told the owner it 'needed a valve adjustment' and sure enough it woulda run good again. Then, it would happen all over again as the valves closed up the lash and then started leaking combustion.
Page 1 of 1 All times are UTC-07:00
Powered by phpBB® Forum Software © phpBB Limited
https://www.phpbb.com/