how to tell if heads have harden valve seats

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earthmover

earthmover

in the tire smoke
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is there anyway to tell if the heads have harden seats in them???besides taken them to the shop..
 
I think he wants to know how to tell if his 906 heads might have ever had hardened seats installed later in their life.
 
To be honest about the hardened exhaust seat subject, I have heard different ideas on this subject. Some say that the valves won't last running unleaded fuel. Others say that unless you are running the engine extremely hard for long periods of time ( like a work hauling heavy loads) to create a lot of heat around the exhaust valve they will be fine without hardened seats. I have a set of small block heads I thought about having hardened seats put in. Since this was brought in your thread yesterday I called my machinist and asked him. He told if I wanted them put in he would do it, but then said he didn't think I really needed them and to save my money for other parts.
 
you should be able to make out the seat, it's a ring bigger than the exhaust valve, if you have seats done already
 
duster360 said:
To be honest about the hardened exhaust seat subject, I have heard different ideas on this subject. Some say that the valves won't last running unleaded fuel. Others say that unless you are running the engine extremely hard for long periods of time ( like a work hauling heavy loads) to create a lot of heat around the exhaust valve they will be fine without hardened seats. I have a set of small block heads I thought about having hardened seats put in. Since this was brought in your thread yesterday I called my machinist and asked him. He told if I wanted them put in he would do it, but then said he didn't think I really needed them and to save my money for other parts.
Click to expand...

^^x2 I've got several friends who've put together motors without the hardened seats. Nobody's burned or sunk a valve or any of that business. The motor on my Dartness is about to turn 10 (thousand) in a few months, and it's got '67 heads that I didn't even do a valve job to. No problems.

And to be totally honest, the only ways that I could think to check (scratching the seat with something of a known hardness) would bugger up the seat and you'd have to redo it anyhow.
 
If your not going to put harden seat in them mix so leaded racing fuel into it, for the first While. Once you have the lead coating on the valve, they should be good for a long while.

When a valve job is done, that lead coating is removed.
You need to get that coating back on.

like a cam and zinc additive. The more "spring pressure", the more a harden seat or leaded racing fuel is required!
 
If you've ever seen a set that's been done, you can clearly see that the material is slightly different color, and you can usually still make out the line between the two different metal surfaces.
 
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