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[Webby the Bear]

Once you get a point that does not seal, the gas erodes the valve and creates the gouges.

Thankfully the seats are hardened so they get away with it.

got ya 

[AndyStobbs]

Original mechanic bang on with his diagnosis then. Credit where its due. Well made heads on the v6 aren't they. Very little room for improvement, there is virtually no unmasking to be had and just a tickle on the porting with a bit if texturing afterwards. Was quite dissapointed not to do more fettling on mine.

[terry paget]

I wonder if aforementioned gorilla dropped something down an inlet tract when the plenum was off and eventually it left the engine via that exhaust valve, damaging it in the process.

In 1968 I had a saddle mounting nut fall off its bolt and dive into the open carburretor throat of my Velocette Venom motorcycle. I took off the head and found it trapped under the exhaust valve.

[Marks DTM Calib]

These heads have been re-worked at some point, the valves are pattern items (the replacement one in the pic is a GM sodium filled 3.0 exhaust valve). The question will be was the re-build done well and was there a mark/damage on the valve when it was installed?

I have further concerns with the head as the stems feel, at first impression, a little loose in the guides. This in reality is not such a major issue given the valve actuation setup (would be a big issue on push rod units with rockers) but, I need to check further.

With the age of the car, you would expect the usual 2.6 stem seal issues but, there also not originaly and all ok.

It is nice to see a good original diag, never ever seen a burnt valve on one of these in the 18-19 years the engine type has been produced.

And your tright Andy, not to much can be done on the heads with respect to porting/flowing (although more can be done on a  2.5/2.6 with opening the throat out to match the 3.0/3.2 inlet bridge)

[05omegav6]

Dread to think what the pot 6 valves look like on mine after the spark plug saga though the bulk of the problem was electrical...

[Marks DTM Calib]

Al, in my experience you find witness marks on the crowns and head combustion chambers but no evidence on the valves and seats.

[05omegav6]

Reassuring 

Given that it still works 100k later, I won't be taking the heads of to look...

[omega3000]

Reassuring 

Given that it still works 100k later, I won't be taking the heads of to look...

Ahh go on 

[05omegav6]

Er...







No

[Marks DTM Calib]

So, further inspection shows a very poorly refurbed set of heads where the guides are reamed to the wrong size and the valve seats cut badly, anybody got a set of late 2.5 or 2.6 heads?

[RobG]

So, further inspection shows a very poorly refurbed set of heads where the guides are reamed to the wrong size and the valve seats cut badly, anybody got a set of late 2.5 or 2.6 heads?

Reply #41 Mark

[M Kerr]

Hello James!

Somehow I haven't come across you for a very long time on here.  My Mig's still going lovely since the bent valve scenario a few years back.  Your assistance was invaluable during the surgery!

I know you'd return a superb motor if offered to you to sort.

[albitz]

So, further inspection shows a very poorly refurbed set of heads where the guides are reamed to the wrong size and the valve seats cut badly, anybody got a set of late 2.5 or 2.6 heads?

3.2 head different ? 

[Marks DTM Calib]

So, further inspection shows a very poorly refurbed set of heads where the guides are reamed to the wrong size and the valve seats cut badly, anybody got a set of late 2.5 or 2.6 heads?

3.2 head different ? 

Sadly yes, larger combustion chamberr

[The Red Baron]

3.0l.  ?