Two destroyed exhaust valves [with pics] - replace valves or entire head?

[Guest]

Soooo...went ahead and took the valves out in preparation of some cleaning and lapping and realized that two of the exhaust valves are completely shot. I'm wondering if you all would recommend just buying two new valves or if replacing the head is easier/cheaper. I figure I will have to have the new valves and seats machined, so I'm trying to take that into account when making my decision. Any advice is appreciated.

[rustybronco]

First clean the carbon off the combustion chambers then re-post with the new pictures.

[gearhead13]

That has to be the worst burnt valve I have ever seen
If you get a new head you should have a valve job done anyway IMO. Find a couple used valves and lap them in.

[Steve]

As suggested, clean the carbon so we can see what's left.

The seats are remarkably durable, but not impervious, they might have survived.

If you find the seats in decent shape, I think I have a couple of valves that should work.

.

[tkent02]

Can I use this picture on the why you need to adjust your valves page?

[chef1366]

The one that Steve had with the glowing red header was pretty bad.

[spyug]

Wow those are the worst I have seen in a long time. What was the mileage on the head?

You could be lucky with the seats but it hard to tell without a bit of cleanup, as the others mention. As they are generally harder to wear out, I'd suspect you would just need a couple of valves, however. At worst a couple of seats too but certainly no need to replace the head unless its cracked or otherwise damaged .

Clean her up and let's see.

[tkent02]

Wow those are the worst I have seen in a long time. What was the mileage on the head?

You could be lucky with the seats but it hard to tell without a bit of cleanup, as the others mention. As they are generally harder to wear out, I'd suspect you would just need a couple of valves, however. At worst a couple of seats too but certainly no need to replace the head unless its cracked or otherwise damaged .

Clean her up and let's see.

Has nothing to do with miles, has everything to do with valve clearance adjustment.

The seats don't get as hot as the valves. They might be OK.

The one that Steve had with the glowing red header was pretty bad.

This one?

[Nessism]

That kind of $hit pis$es me off. Damn hacks ignoring basic maintenance. Good thing it's just the engine and not the wheels or something. Stupid previous owner would be dead now.

[TheDuke]

Can I use this picture on the why you need to adjust your valves page?

Go for it!

[TheDuke]

Any advice on the best way to clean her up for her second photo shoot?

[Steve]

The one that Steve had with the glowing red header was pretty bad.

I was going to post that, then I saw that Tom beat me to it.

Any advice on the best way to clean her up for her second photo shoot?

Some of the pros might shuder, but I have used a wire brush in my drill.

Light pressure will take off the carbon, just don't push hard enough to take away any metal.



Don't have a picture handy of the head, but here is how the pistons ended up:




.

[robertbarr]

[QUOTE=TheDuke;1949231]Soooo...went ahead and took the valves out in preparation of some cleaning and lapping





On the other hand, it'd look great with a side order of breaded mushrooms.

[tkent02]

Nah, sell it on Ebay, "Slight cosmetic damage"

[TheDuke]

Ebay is a little light on exhaust valves for the '79 750 at the moment. Anyone have any for sale???